CN101240001B - 2'-Fluoronucleosides - Google Patents

Abstract

2' -fluoronucleoside compounds are disclosed for the treatment of hepatitis B infection, hepatitis C infection, HIV and abnormal cell proliferation including tumors and cancers. These compounds have the general formula , (II), (III), (IV) or a pharmaceutically acceptable salt thereof, wherein the base is a purine or pyrimidine base; r¹Is OH, H, OR³，N₃CN, halogen including F, or CF₃Lower alkyl, amino, lower alkylamino, di-lower alkylamino, or alkoxy; r²Is H, phosphate, including monophosphate, diphosphate, triphosphate, or a stable phosphate prodrug; acyl, or other pharmaceutically acceptable leaving group, which when used in vivo provides R²A compound that is H or phosphate; sulfonates including alkyl or aralkyl sulfonyl including methylsulfonyl, benzyl wherein the phenyl group is optionally substituted with one or more substituents as described above for aryl, lipids, amino acids, peptides or cholesterol; and R is³Is an acyl, alkyl, phosphate or other pharmaceutically acceptable leaving group, i.e. a group which is capable of cleaving to the parent compound when used in vivo.

Description

2'-Fluoronucleosides

This application is a divisional application of an application whose international filing date is February 25, 1999, whose international application number is PCT/US99/04051 (national application number is 99805472.0), and whose invention name is "2'-fluoronucleoside". the

The invention described herein was made with government support under Grant No. AI32351 awarded by the National Department of Health. The United States Government has asserted rights in this invention. the

technical field

The invention belongs to the field of medicinal chemistry, and specifically includes 2'-fluoronucleosides, a preparation method and application thereof. the

Background technique

Synthetic nucleosides such as 5-iodo-2'-deoxyuridine and 5-fluoro-2'-deoxyuridine have been used for some years in the treatment of cancer and herpes viruses. Since the 1980s, synthetic nucleosides have also been beneficial in the treatment of HIV, hepatitis and Epstein-Barr virus. the

In 1981, Acquired Immunodeficiency Syndrome (AIDS) was recognized as a disease that seriously compromises the human immune system and which almost without exception leads to death. In 1983, the cause of AIDS was identified as human immunodeficiency virus (HIV). In 1985, it was reported that the synthetic nucleoside 3'-azido-3'-deoxythymidine (AZT) inhibits the replication of human immunodeficiency virus. Since then, several other synthetic nucleosides have been demonstrated, including 2',3'-dideoxyinosine (DDI), 2',3'-dideoxycytidine (DDC) and 2',3'-dideoxy -2',3'-didehydrothymidine (D4T), effective against HIV. Following the generation of 5'-triphosphate by cellular kinases through cellular phosphorylation, these synthetic nucleosides are incorporated into the growing chain of viral DNA, causing chain termination due to the absence of the 3'-hydroxyl group. They also inhibit viral reverse transcriptase. the

The success of various synthetic nucleosides in inhibiting HIV in vivo or in vitro has led some investigators to design and test nucleosides that replace heteroatoms with carbon atoms at the 3'-position of the nucleosides. European Patent Application No. 0337713 and U.S. Patent No. 5,041,449 (to BioChem Pharma, Inc.), disclose racemic 2-substituted-4-substituted-1,3-dioxolanes that exhibit antiviral active. U.S. Patent No. 5,047,407 and European Patent Application No. 0382526 (also belonging to BioChcmPharma, Inc.), disclose certain racemic 2-substituted-5-substituted-1,3-oxathia rings with antiviral activity Pentane nucleosides, and particularly pointed out that 2-hydroxymethyl-5-(cytosin-1-yl)-1,3-oxathiolane (hereinafter referred to as BCH-189) has nearly the same anti-HIV activity with minimal toxicity. The (-)-enantiomer of the racemic mixture BCH-189, known as 3TC, is disclosed by Liotta et al. in US Patent No. 5,539,116 and is currently marketed in the US in combination with AZT for the treatment of HIV. the

It has also been disclosed that cis-2-hydroxymethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane ("FTC") has potent anti-HIV activity. Schinazi et al., "Selection of racemic mixtures and enantiomers with cis-5-fluoro-1-[2-hydroxymethyl-1,3-oxathiolan-5-yl]cytosine Sexual suppression of human immunodeficiency virus" Antimicrobial Agents and Chemotherapy, November 1992, pp.2423-2431. See also U.S. Patent No. 5,210,085; WO 91/11186 and WO 92/14743. the

Another virus that causes serious health problems in humans is hepatitis B virus (hereinafter "HBV"). HBV is the second leading cause of human cancer after smoking. The mechanism by which HBV induces cancer is unclear. It is speculated that it causes tumor progression directly, or indirectly through chronic inflammation, liver cirrhosis, and cell regeneration associated with infection. the

After an incubation period of 2 to 6 months, when the infected subject is not aware of the infection, HBV infection can lead to hepatitis and liver damage, which causes abdominal pain, jaundice, and increased concentrations of certain enzymes in the blood. HBV can cause fulminant hepatitis, a rapidly progressive and often fatal disease in which much of the liver is destroyed. the

Generally speaking, patients with acute hepatitis can recover. However, in some patients, high concentrations of viral antigens remain in the blood for prolonged or indefinite periods, causing chronic infection. Chronic infection can lead to chronic persistent hepatitis. Patients with chronic persistent HBV are most prevalent in developing countries. By mid-1991, there were approximately 225 million chronic HBV carriers in Asia alone and nearly 300 million carriers worldwide. Chronic persistent hepatitis can cause fatigue, cirrhosis and hepatocellular carcinoma, a major type of liver cancer. the

In Western industrialized countries, groups at high risk for HBV infection include those who have been in contact with HBV carriers or their blood samples. The epidemiology of HBV is similar to acquired immunodeficiency syndrome, which is why HBV infection is common in HIV-infected or AIDS patients. However, HBV is more susceptible to contact infection than HIV. the

Both FTC and 3TC exhibited anti-HBV activity. Furman et al., "The (-) and (+) enantiomers of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]-cytosine Antimicrobial Agents and Chemotherapy, December 1992, pp.2686-2692; and Cheng et al., Journal of biological Chemistry, Volume 267(20), pp.13938-13942 (1992). the

Vaccines derived from human serum have been developed to immunize patients against HBV. Although it has been found to be effective, the production of this vaccine has been somewhat troublesome due to the limited availability of human serum from chronic carriers and the long and costly purification steps. In addition, each batch of vaccine prepared from a different serum must be tested in chimpanzees to ensure safety. Vaccines have also been prepared through genetic engineering. Daily treatment with a genetically engineered protein, alpha-interferon, is also promising. the

Hepatitis C virus ("HCV") is a major cause of post-transfusion infection and sporadic non-A, non-B hepatitis (Alter, H.J. (1990) J. Gastro. Hepatol. 1:78-94; Dienstag, J.L. (1983) Gastro 85 : 439-462). Despite improved screening methods, HCV is still the cause of at least 25% of acute viral hepatitis in many countries (Alter, H.J. (1990), supra; Dienstag, J.L. (1983), supra; Alter M.J. et al., (1990a ) J.A.M.A.264:2231-2235; Alter M.J. et al., (1992) N.Engl.J.Med.M:1899-1905; Alter, M.J. et al., (1990b) N.Engl.J.Med.321:1494-1500 ). HCV infection is insidious in a high proportion of chronically infected (and infectious) carriers, who may not show clinical symptoms for many years. The high rate of transition from acute infection to chronic infection (70-100%) and liver disease (>50%), its widespread distribution and lack of a vaccine make HCV a significant cause of morbidity and mortality. the

A tumor is an irregular, tissue-destructive proliferation of cell growth. A tumor is malignant or cancerous if it is invasive and metastatic. Invasiveness refers to the propensity of a tumor to penetrate into surrounding tissues, disrupt the underlying tissue boundaries, and thus enter the normal systemic circulatory system. Metastasis refers to the tendency of tumors to migrate to other areas of the body and establish areas of proliferation beyond the site of original appearance. the

Cancer is now the second leading cause of death in the United States. 8,000,000 people have been diagnosed with cancer in the United States, with an estimated 1,208,000 new diagnoses in 1994. More than 500,000 people die from this disease every year in this country. the

At the molecular level, cancer is not well understood. Exposure of cells to carcinogens, such as certain viruses, certain chemicals or radiation, is known to cause DNA changes that inactivate "suppressor" genes or activate "oncogenes". Suppressor genes are growth-regulating genes that, when mutated, can no longer control cell growth. Oncogenes start as normal genes (called proto-oncogenes) that become transforming genes through mutation or alteration of the expressed sequence. The product of the transforming gene causes inappropriate cell growth. More than 20 normal cell genes can be turned into cancer-causing genes through genetic changes. Transformed cells differ from normal cells in many ways, including cell morphology, cell-to-cell interactions, membrane composition, cytoskeleton structure, protein secretion, gene expression and death (transformed cells can grow indefinitely). the

All the different cell types of the body can transform into benign or malignant tumor cells. The most common tumor site is the lung, followed by the colorectum, breast, prostate, bladder, pancreas, and ovary. Other more prevalent cancer types include leukemias, cancers of the central nervous system including brain tumors, melanomas, lymphomas, erythroleukaemias, uterine cancers, and head and neck cancers. the

Cancer is now mainly treated for three years with one or a combination of the following methods: surgery, radiotherapy, and chemotherapy. Surgery involves removing most diseased tissue. Although, surgery is sometimes effective in removing tumors located in certain sites such as the breast, rectum and skin, it cannot be used to treat tumors located in other areas such as the spine, nor can it be used to treat disseminated neoplastic conditions such as leukemia. the

Chemotherapy involves disrupting cell replication or cell metabolism. It is most commonly used to treat leukemia and cancers of the breast, lung and testicles. the

There are five major classes of chemotherapeutic agents currently used to treat cancer: natural products and their derivatives; anthracyclines; alkylating agents; antiproliferative drugs (also known as antimetabolites); and hormones. Chemotherapeutic agents are often referred to as antineoplastic agents. the

Alkylating agents are believed to work by alkylating or cross-linking guanine and possibly other bases in DNA, preventing cell division. Typical alkylating agents include nitrogen mustards, ethyleneimine compounds, alkyl sulfates, cisplatin, and various nitrosoureas. The disadvantage of these compounds is that they bind not only malignant cells, but also other naturally dividing cells, such as cells of bone marrow, skin, gastrointestinal mucosa and placental tissue. the

Antimetabolites are generally reversible or irreversible enzyme inhibitors, or compounds that interfere with nucleic acid replication, translation or transcription. the

Several synthetic nucleosides have been determined to exhibit anticancer activity. A well-known nucleoside derivative with strong anticancer activity is 5-fluorouracil. 5-Fluorouracil has been used clinically for the treatment of malignant tumors including, for example, carcinoma, sarcoma, skin cancer, cancer of the digestive organs, and breast cancer. But 5-fluorouracil causes severe side effects such as nausea, alopecia, diarrhea, stomatitis, leukocytic thrombocytopenia, anorexia, pigmentation and edema. Derivatives of 5-fluorouracil having anticancer activity are described in U.S. Patent No. 4,336,381, and Japanese Patent Application Nos. 50-50383, 50-50384, 50-64281, 51-146482 and 53-84981. the

US Patent No. 4,000,137 describes the antilymphoblastic activity of the products of inosine, adenosine or cytidine and methanol or ethanol peroxide peroxidation. the

Cytarabine (also known as Cytarabin, araC and Cytosar) is a nucleoside analogue of deoxycytosine, which was first synthesized in 1950 and used as a clinical drug in 1963. It is currently the most important drug for the treatment of acute myeloid leukemia. It is also active against acute lymphoblastic leukemia and is less commonly used in the treatment of chronic myeloid leukemia and non-Hodgkin's lymphoma. The main effect of cytarabine is to inhibit the synthesis of nucleic acid DNA. Handschumacher, R. and Cheng, Y., "Purine and pyrimidine antimetabolites", Cancer Medicine, Chapter XV-1, 3rd ed., edited by J. Holland et al., published by Lea and Febigol. the

5-Azacitidine belongs to the cytidine class, which is mainly used in the treatment of acute myeloid leukemia and myelodysplastic syndrome. the

2-Fluoroadenosine-5'-phosphate (Fludara, also known as FaraA) is one of the most effective drugs for the treatment of chronic lymphocytic leukemia. This compound works by inhibiting DNA synthesis. Treatment of cells with F-araA was associated with accumulation of cells at the GI/S phase margin and in S phase; thus, it is a specific drug for the S phase of the cell cycle. Incorporation of the active metabolite F-araATP prevents DNA chain elongation. F-araA is also a strong inhibitor of ribonucleotide reductase, the key enzyme responsible for the formation of dATP. the

2-Chlorodeoxyadenosine is used in the treatment of low-grade B-cell neoplasms such as chronic lymphocytic leukemia, non-Hodgkin's lymphoma, and hairy cell leukemia. the

In designing new bioactive nucleosides, several attempts have been made to incorporate fluorine substituents into the carbohydrate rings of nucleosides. Fluorine was suggested as a substituent because it might act as an isopolar and isobulkic mimic of hydroxyl, because the C-F bond length (1.35 angstroms) is very close to the C-O bond length (1.43 angstroms), and because fluorine is the recipient of hydrogen bonds. body. Fluorine enables significant electronic changes in the molecule with minimal steric interference. Substitution of other groups in the molecule with fluorine can cause changes in substrate metabolism due to the high strength of the C-F bond (116 kcal/mol versus C-H = 100 kcal/mol). the

Several references report the synthesis and use of 2'-arabinosylfluoronucleosides (ie, nucleosides in which the 2'-fluoro group is in the "up" configuration). Several reports have reported that 2-fluoro-β-D-arabinofuranosyl nucleosides exhibit anti-hepatitis B and herpes activity. See, for example, U.S. Patent No. 4,666,892 (Fox et al); U.S. Patent No. 4,211,773 (Lopez et al); Su et al, Nucleosides. 136, "Several 1-(2-deoxy-2-fluoro-β-D-furan Glycosyl)-5-Alkyluracil Synthesis and Antiviral Effects"; "Some Structure-Activity Relationships", J.Med Chem., 1986, 29, 151-154; Borthwick et al., "Carbocyclic 2′-Arabinose - Fluoro-guanosine: Synthesis and enzymatic resolution of a potent new antiherpetic agent," J. Chem. Soc., Chem. Commun, 1988; Wantanabe et al., "Active anti-AIDS nucleoside 3'-azido Synthesis and anti-HIV activity of 2'-"up"-fluoro analogs of -3'-deoxythymidine (AZT) and 2',3'-dideoxycytidine (DDC), J.Med.Chem.1990.33 , 2145-2150; Martin et al., "Synthesis and antiviral activity of mono- and difluoro analogs of pyrimidine dideoxyribonucleosides against human immunodeficiency virus (HIV-1)," J Med, Chem.1990, 33, 2137-2145; Sterzycki et al., "Synthesis and anti-HIV activity of some 2'-fluoro-pyrimidine-containing nucleosides," J. Med. Chem. 1990, and EPA 0316017 (applied by Sterzycki et al.); and Montgomery et al. , "9-(2-deoxy-2-fluoro-β-D-arabinosyl)guanosine: a class of metabolically stable 2'-deoxyguanosine cytotoxic analogs", U.S. Patent No. 5,246,924 discloses the treatment Methods for hepatitis, including the use of 1-(2'-deoxy-2'-fluoro-β-D-arabinosyl)-3-ethyluracil), also known as "FEAU". U.S. Patent No. 5,034,518 discloses 2-fluoro-9-(2-deoxy-2-fluoro-β-D-arabinosyl)adenosine nucleosides which alter the Metabolism of adenosine to exhibit anticancer activity. EPA 0292023 discloses that certain β-D-2'-fluoroarabinosides have antiviral infection activity. the

US Patent No. 5,128,458 discloses antiviral agents beta-D-2',3'-dideoxy-4'-thioribonucleosides. US Patent No. 5,446,029 discloses 2',3'-dideoxy-3'-fluoronucleosides having anti-hepatitis activity. the

European Patent Application No. 0409227 A2 discloses certain 3'-substituted β-D-pyrimidine and purine nucleosides for the treatment of hepatitis B. the

It has also been disclosed that L-FMAU (2'-fluoro-5-methyl-β-L-arabinosyluracil) is a potent anti-HBV and anti-EBV agent. See Chu et al., "Use of 2′-fluoro-5-methyl-β-L-arabinosyluracil as a novel antiviral agent for the treatment of hepatitis B virus and Epstein-Barr virus," Antimicrobial Agents and Chemotherapy, April 1995 , pp. 979-981; Balakrishna et al., "Inhibition of hepatitis B virus by a novel L-nucleoside, 2′-fluoro-5-methyl-β-L-arabinofuranosyluracil", Antimicrobial Agents and Chemotherapy, February 1996, pp. 380-356; US Patent Nos. 5,587,362; 5,567,688; and 5,565,438. the

US Patent Nos. 5,426,183 and 5,424,416 disclose processes for the preparation of 2'-deoxy-2',2'-difluoronucleosides and 2'-deoxy-2'-fluoronucleosides. See also "Kinetic studies of 2',2'-difluorodeoxycytidine (gemcitabine) with purified human deoxycytidine kinase and cytidine deaminase", BioChemical Pharmacology, Vol. 45 (No. 9) 4857 -1861 pages, 1993. the

US Patent No. 5,446,029 (Eriksson et al.) discloses certain 2',3'-dideoxy-3'-fluoronucleosides having anti-hepatitis B activity. US Patent No. 5,128,458 discloses certain 2',3'-dideoxy-4'-thionucleosides wherein the 3'-substituent is H, azide or fluorine. WO 94/14831 discloses certain 3'-fluoro-dihydropyrimidine nucleosides. WO 92/08727 discloses β-L-2'-deoxy-3'-fluoro-5-substituted uridine nucleosides for the treatment of herpes simplex 1 and 2. the

EPA Publication No. 0352248 discloses a broad class of L-ribofuranosyl purine nucleosides for the treatment of HIV, herpes and hepatitis. Although certain 2'-fluoropurine nucleosides fall within this general class, no information is given in their descriptions for the preparation of these compounds, and they are not specifically disclosed or listed as preferred in the description. The specification does not disclose how to prepare 3'-ribofuranosyl fluorinated nucleosides. A similar description is found in WO 88/09001 (Aktiebolaget Astra application). the

European patent application 0357571 discloses a large group of β-D and α-D pyrimidine nucleosides for the treatment of AIDS, which generally includes nucleosides which may be substituted by a fluorine group at the 2' or 3' position. However, there is no specific disclosure of 2'-fluoronucleosides or their preparation in this broad group. the

EPA 0463470 discloses the preparation method of (5S)-3-fluoro-tetrahydro-5[(hydroxyl)methyl]-2-(3H)-furanone, which is the preparation method of 2′-fluoro-2′,3′- A known intermediate of dideoxynucleosides such as 2'-fluoro-2',3'-dideoxycytidine. the

U.S.S.N.07/556,713 discloses β-D-2'-fluoroarabinosyl nucleosides, and methods for their preparation, which are intermediates in the synthesis of 2',3'-dideoxy-2'-fluoroarabinosides . the

US Patent No. 4,625,020 discloses a method for preparing 1-halo-2-deoxy-2-fluoroarabinosyl derivatives with protecting groups from 1,3,5-tri-O-acyl-ribofuranose. the

Disclosure of β-L-2'-fluoro-ribofuranosyl nucleosides for medical use including treatment of HIV, hepatitis (B or C) or proliferative disorders is lacking. At least with regard to 2'-ribofuranosyl nucleosides, this may be due to the previous perceived difficulty of placing the fluorine group in the 2'-ribofuranosyl configuration. For L-2'-fluoro-2',3'-unsaturated purine nucleosides, it may be due to the instability of purine nucleosides in acidic media, resulting in the cleavage of the glucosyl bond. the

Given the fact that HIV-acquired immunodeficiency syndrome, AIDS-related syndrome, and hepatitis B and C viruses are circulating throughout the world and have a tragic impact on infected patients, there is also a need to provide new, Requirements for agents that are effective and of low toxicity to the subject being treated. Furthermore, there is a need to provide new antiproliferative agents. the

Contents of the invention

Accordingly, it is an object of the present invention to provide methods and compositions for treating patients infected with hepatitis B or hepatitis C. the

Another object of the present invention is to provide methods and compositions for treating HIV-infected patients. the

Another object of the present invention is to provide novel antiproliferative agents. the

Yet another object of the present invention is to provide a novel process for the preparation of 2'-fluoro-ribofuranosyl nucleosides. the

Another object of the present invention is to provide the preparation of 2', 3'-dideoxy-2', 3'-didehydro-2'-fluoro-L-glyceryl-pent-2-enyl-furanosyl nucleoside new method. the

specific implementation plan

In one embodiment of the invention, there is provided a 2'-alpha-fluoro-nucleoside of the following structure:

in

The base is a purine or pyrimidine base as further defined herein;

R ¹ is OH, H, OR ³ , N ₃ , CN, halogen including F, or CF ₃ , lower alkyl, amino, lower alkylamino, di-lower alkylamino, or alkoxy, and base refers to purine or pyrimidine bases;

R ² is H. Phosphates include monophosphate, diphosphate, triphosphate, or stable phosphate prodrugs; acyl groups, or other pharmaceutically acceptable leaving groups that provide R ² when used in vivo Compounds that are H or phosphate; sulfonates include alkyl or aralkylsulfonyl (including methylsulfonyl), benzyl (wherein the phenyl is optionally substituted with one or more of the above aryl definitions) substituents), lipids (including phospholipids), amino acids, peptides, or cholesterol; and

^R3 is an acyl, alkyl, phosphate or other pharmaceutically acceptable leaving group, ie, a group that cleaves to the parent compound when used in vivo.

In a second embodiment, there is provided a 2'-fluoronucleoside of the formula:

wherein the substituents are as defined above. the

In a third embodiment, there is provided a 2'-fluoronucleoside of the formula:

wherein the substituents are as defined above. the

In a fourth embodiment, there is provided a 2'-fluoronucleoside of the structure:

wherein the substituents are as defined above. the

These 2'-fluoronucleosides can be in the β-L or β-D configuration. The β-L configuration is preferred. the

Such 2'-fluoronucleosides are biologically active molecules which are used in the treatment of hepatitis B, hepatitis C or HIV. These compounds are also useful in the treatment of abnormal proliferation of cells, including tumors and cancers. The spectrum of activity can be readily determined by the assays described herein or by evaluating the compounds using other confirmatory assays. the

In another embodiment, for the treatment of hepatitis or HIV, the active compound or its derivative or salt can be administered in combination or alternately with other antiviral agents (such as anti-HIV agents or anti-hepatitis agents, including those described in the above formula) . Generally, in combination therapy, effective amounts of two or more agents are administered together, while in alternation therapy, effective amounts of each agent are administered sequentially. The amount administered depends on the rate of absorption, inactivation, and excretion of the drug, as well as other factors known to those skilled in the art. It is to be mentioned that this dosage will also vary with the severity of the condition being treated. It is further understood that for any particular subject, the particular dosage regimen and procedure will be adjusted over time according to the needs of the individual and the professional judgment of the administerer or person directing the administration of these compositions. the

Non-limiting examples of antiviral agents that can be combined with the compounds disclosed herein include 2-hydroxymethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane ( FTC); the (-)-enantiomer of 2-hydroxymethyl-5-(cytosin-1-yl)-1,3-oxathiolane (3TC); Cabover, A Ciclovir, Interferon, Famciclovir, Penciclovir, AZT, DDI, DDC, D4T, Abacavir, L-(-)-FMAU, L-DDA Phosphate Prodrug and β-D-dioxolane Nucleosides such as β-D-dioxolanyl-guanine (DG), β-D-dioxolanyl-2,6-diaminopurine (DAPD), and β-D-di Oxolane-6-chloropurine (ACP), non-nucleoside RT inhibitors such as nevirapine, MKC-442, DMP-266 (sustiva) and protease inhibitors such as indinavir, saquinavir, AZT, DMP- 450 etc. the

These compounds are also useful in the treatment of equine infectious anemia virus (EIAV), feline immunodeficiency virus and simian immunodeficiency virus (Wang, S., Montelaro, R., Schinazi, R.F., Jagerski, B. and Mellors, J.W.: " Activity of Nucleoside and Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs) Against Equine Infectious Anemia Virus (EIAV), First National Conference on Human Retro virus and Related Infections, Washington, DC, December 12-16, 1993; Sellon, D.C., "Equine Infectious Anemia", Vet. Clin. North Am. Equine Pract. USA, 9:321-336, 1993; Philpott, M.S., Ebner, J.P., Hoover, E.A., "Using Quantitative Polymerase Chain Reaction Evaluation of 9-(2-phosphorylmethoxyethyl)adenine in the treatment of feline immunodeficiency virus", Vet. Immunol. Immunopathol. 35: 155166, 1992). the

Novel and completely diastereoselective methods for introducing fluorine onto non-carbohydrate sugar ring precursors are also provided. The method involves a chiral, non-carbohydrate sugar ring precursor (4S)-5-(protected oxy)-pentan-4-lactone (which can be prepared from L-glutamic acid) and an electrophilic source of fluorine Including but not limited to the reaction of N-fluoro-(bis)benzenesulfonimide to obtain the key intermediate fluorolactone 6. The fluorinated lactone is reduced to lactone and acetylated to obtain anomeric acetate, which is then used to synthesize some new β-L-α-2′-fluoronucleosides. The corresponding D-enantiomer can also be synthesized using D-glutamic acid as starting material. the

In another alternative embodiment, dehydrofluorinated alkenyl sugars are prepared and then converted to 2',3'-dideoxy-2',3'-didehydro-2'-fluoronucleosides or β-L or β-D-arabinosyl-2'-fluoronucleosides, as described below. the

Also given is a simple method for the preparation of 2',3'-dideoxy-2',3'-didehydro-2'-fluoronucleosides, which involves combining silylated 6-chloropurine with key The intermediate is directly condensed, and the key intermediate consists of L-2,3-O-isopropylidene glyceraldehyde (glyceraldenhyde). the

Detailed description of the invention

The invention disclosed herein relates to a compound, method and composition for the treatment of HIV, hepatitis (B or C) or abnormal cell proliferation in a human or other animal host comprising the use of An effective amount of 2'-fluoro-nucleoside, a pharmaceutically acceptable derivative (including compounds that have been alkylated or acylated at the 5'-position or at a purine or pyrimidine), or a pharmaceutically acceptable salt thereof. Compounds of the invention possess antiviral (ie anti-HIV-1, anti-HIV-2 or anti-hepatitis (B or C)) activity, or antiproliferative activity, or are metabolized to compounds having these activities. the

In summary, the present invention includes the following features:

(a) β-L and β-D-2'-fluoronucleosides, as described herein, and pharmaceutically acceptable derivatives and pharmaceutically acceptable salts thereof,

(b) β-L and β-D-2'-fluoronucleosides, as described herein, and pharmaceutically acceptable derivatives and pharmaceutically acceptable salts thereof, for use in pharmaceutical therapy, for example, for the treatment or prevention of HIV or hepatitis ( B or C) infection or treatment of abnormal cell proliferation;

(c) 2',3'-dideoxy-2',3'-didehydro-2'-fluoro-L-glyceryl-pent-2-enyl-furanosyl nucleoside, and its pharmaceutical derivatives substances and pharmaceutically acceptable salts, which are used in pharmaceutical therapy, for example, to treat or prevent HIV or hepatitis (B or C) infection or to treat abnormal cell proliferation;

(d) the use of these 2'-fluoronucleosides and their pharmaceutically acceptable derivatives and salts in the preparation of drugs for the treatment of HIV or hepatitis infection or the treatment of abnormal cell proliferation;

(e) Pharmaceutical preparations containing 2'-fluoronucleosides or their pharmaceutically acceptable derivatives or their salts and pharmaceutically acceptable carriers or diluents;

(f) methods for the preparation of β-L and β-D-2'-α-fluoronucleosides, as detailed below, and

(g) A method for preparing 2',3'-dideoxy-2',3'-didehydro-2'-fluoro-L-glyceryl-pent-2-enyl-furanosyl nucleoside. the

I. Active compounds, their physiologically acceptable derivatives and salts

Provides 2'-α-fluoro-nucleosides with the following structure:

wherein R ¹ is OH, H, OR ³ , N ₃ , CN, halogen (including F), or CF ₃ , lower alkyl, amino, lower alkylamino, di-lower alkylamino, or alkoxy, and the base The base refers to a purine or pyrimidine base;

^R2 is H, and phosphate includes monophosphate, diphosphate, triphosphate, or a stable phosphate prodrug; an acyl group, or other pharmaceutically acceptable leaving group that provides ^R2 when used in vivo Compounds that are H or phosphate; sulfonates include alkyl or aralkylsulfonyl (including methylsulfonyl), benzyl (wherein the phenyl is optionally substituted with one or more of the above aryl definitions) substituents), lipids (including phospholipids), amino acids, peptides, or cholesterol; and

^R3 is an acyl, alkyl, phosphate or other pharmaceutically acceptable leaving group, ie, a group that cleaves to the parent compound when used in vivo.

In a second embodiment, there is provided a 2'-fluoronucleoside of the formula:

In a third embodiment, there is provided a 2'-fluoronucleoside of the formula:

In a fourth embodiment, there is provided a 2'-fluoronucleoside of the structure:

Herein, unless otherwise specified, the term alkyl refers to saturated linear, branched or cyclic primary, secondary or tertiary _C1 to _C10 hydrocarbons, and particularly includes methyl, ethyl, propyl, isopropyl, Cyclopropyl, butyl, isobutyl, tert-butyl, pentyl, cyclopentyl, isopentyl, neopentyl, hexyl, isohexyl, cyclohexyl, cyclohexylmethyl, 3-methylpentyl- 2,2-dimethylbutyl, and 2,3-dimethylbutyl. The alkyl group may be optionally substituted with one or more moieties selected from the group consisting of hydroxy, amino, alkylamino, arylamino, alkoxy, aryloxy, nitro, cyano, sulfonic acid, sulfate, Phosphonic acid, phosphate or phosphonate, which may be unprotected or protected as desired, as known to those skilled in the art, for example as taught by Greene et al., Protective Groups in Organic Synthesis , John Wiley and Sons, 2nd Edition, 1991 , incorporated herein by reference.

The term lower alkyl as used herein, unless otherwise specified, refers to a _C1 to _C4 saturated straight chain, branched chain or cyclic (if appropriate eg cyclopropyl) alkyl group.

The term alkylamino or arylamino refers to an amino group bearing one or two alkyl or aryl substituents, respectively. the

The term "protecting" herein, unless otherwise defined, refers to a group added to an oxygen atom, nitrogen atom or phosphorus atom to prevent further reaction or for other purposes. A variety of protecting groups for oxygen or nitrogen atoms are known to those skilled in the art of organic synthesis. Herein, unless otherwise specified, the term aryl refers to phenyl, biphenyl or naphthyl, and preferably phenyl. Aryl groups may be selectively substituted with one or more moieties selected from the group consisting of hydroxyl, amino, alkylamino, arylamino, alkoxy, aryloxy, nitro, cyano, sulfonic acid, sulfate, Phosphonic acid, phosphate or phosphonate, which may be unprotected or protected as desired, as known to those skilled in the art, for example Greene et al., Protective Groups in Organic Synthesis , John Wiley and Sons, Second Edition, 1991 taught.

The term alkaryl or alkylaryl refers to an alkyl group with an aryl substituent. The term aralkyl or arylalkyl refers to an aryl group with an alkyl substituent. the

The term halogen, as used herein, includes chlorine, bromine, iodine and fluorine. the

烷基嘧啶，C₅-苄基嘧啶，C₅-卤代嘧啶，5-乙烯基嘧啶，C₅-乙炔基嘧啶，C₅-酰基嘧啶，C₅-羟基烷基嘌呤，C₅-酰氨基嘧啶， C₅-氰基嘧啶，C₅-硝基嘧啶，C₅-氨基嘧啶，N²-烷基嘌呤，N²-烷基-6-硫代嘌呤，5-氮杂胞嘧啶基，5-氮杂尿嘧啶基，三氮杂环戊并吡啶基，咪唑并吡啶基，吡咯并嘧啶基和吡唑并嘧啶基。嘌呤碱基包括但不限于鸟嘌呤，腺嘌呤，次黄嘌呤，2，6-二氨基嘌呤和6-氯嘌呤。碱基上的官能氧或氮原子基团可以按照需要或要求保护。适宜的保护基是本领域技术人员熟知的，并包括三甲基甲硅烷基、二甲基己基甲硅烷基、叔丁基二甲基甲硅烷基和叔丁基联苯基甲硅烷基、三苯甲基、烷基、酰基如乙酰基和丙酰基、甲磺酰基和对甲苯磺酰基。  The term purine or pyrimidine base includes, but is not limited to, adenine, ^N6 -alkylpurine, ^N6 -acylpurine (wherein the acyl group is C(O)(alkyl, aryl, alkylaryl, or arylalkyl ), N ⁶ -benzyl purine, N ⁶ -halogenated purine, N ⁶ -vinyl purine, N ⁶ -ethyl purine, N ⁶ -acyl purine, N ⁶ -hydroxyalkyl purine, N ⁶ -thioalkane base purine, N ² -alkyl purine, N ² -alkyl-6-thiopurine, thymine, cytosine, 5-fluorocytosine, 5-methylcytosine, 6-azapyrimidine (including 6- azacytosine), 2- and/or 4-mercaptopyrimidine, uracil, 5-halouracil (including 5-fluorouracil),

Alkylpyrimidine, _C5 -Benzylpyrimidine, _C5 -Halopyrimidine _, 5-Vinylpyrimidine, _C5 -Ethynylpyrimidine, _C5 -Acylpyrimidine, C5-Hydroxyalkylpurine, _C5 -Acylamino Pyrimidine, C ₅ -cyanopyrimidine, C ₅ -nitropyrimidine, C ₅ -aminopyrimidine, N ² -alkylpurine, N ² -alkyl-6-thiopurine, 5-azacytosine, 5 - azauracilyl, triazacylopyridyl, imidazopyridyl, pyrrolopyrimidinyl and pyrazolopyrimidinyl. Purine bases include, but are not limited to, guanine, adenine, hypoxanthine, 2,6-diaminopurine, and 6-chloropurine. Functional oxygen or nitrogen atom groups on bases can be protected as needed or required. Suitable protecting groups are well known to those skilled in the art and include trimethylsilyl, dimethylhexylsilyl, tert-butyldimethylsilyl and tert-butylbiphenylsilyl, trimethylsilyl, Benzyl, alkyl, acyl such as acetyl and propionyl, methanesulfonyl and p-toluenesulfonyl.

When administered to a patient, the active compound may be used in a form which directly or indirectly provides the parent compound or any derivative thereof which is active. Non-limiting examples are pharmaceutically acceptable salts (alternatively referred to as "physiologically acceptable salts"), or compounds that have been alkylated or acylated at the 5'-position or at the purine or pyrimidine base (alternatively referred to as " Pharmaceutical Derivatives"). In addition, modifications can affect the biological activity of the compound, in some cases increasing the activity of the parent compound. The compounds can be readily evaluated by preparing derivatives and testing their antiviral activity according to the methods described herein or other methods known to those skilled in the art. the

The term acyl refers to carboxylic acid esters wherein the non-carbonyl portion of the ester group is selected from straight, branched or cycloalkyl or lower alkyl, alkoxyalkyl includes methoxymethyl, aralkyl includes benzyl, aryl Oxyalkyl such as phenoxymethyl, aryl including phenyl optionally substituted by halogen, _C1 to _C4 alkyl or _C1 to _C4 alkoxy, sulfonate such as alkyl or aralkyl Sulfonyl groups include methanesulfonyl, mono-, di- or triphosphate, trityl or monomethoxytrityl, substituted benzyl, trialkylsilyl (e.g. dimethyl tert-butylsilyl ) or diphenylmethylsilyl. Aryl groups in esters preferably include phenyl.

As used herein, the term "substantially free" or "substantially lacking" means that a nucleoside composition contains at least 95% to 98%, or more preferably 99% to 100%, of the specified enantiomer of that nucleoside. the

Nucleoside Prodrug Preparations

Any of the nucleosides described herein can be administered as a nucleoside prodrug to increase the activity, bioavailability, stability or alter the properties of the nucleoside. Several nucleotide prodrug ligands are known. In general, alkylation, acylation, or other lipophilic modification of the mono-, di-, or triphosphate of a nucleoside increases the stability of that nucleotide. Examples of substituents which may replace one or more hydrogen atoms on the phosphate group are alkyl groups, aryl groups, steroids, carbohydrates including sugars, 1,2-diacylglycerols and alcohols. Much is described in R. Jones and N. Bischofberger, Antiviral Research, 27 (1995) 1-17. Any of these compounds can be used in combination with the nucleosides disclosed herein to achieve the desired effect. the

The active nucleosides may also be provided in the form of 5'-phosphoether lipids or 5'-ether lipids, as disclosed in the following documents, which are incorporated herein by reference: Kucera, L.S., N.lyer, E. Leake, A. Raben, Modest E.K., D.L.W., and C. Piantadosi. 1990, "Novel membrane-interacting ether lipids that inhibit infectious HIV-1 production and induce defective virus formation", AIDS Res. Hum. Retro Viruses. 6: 491-501; Piantadosi, C., J. Marasco, C.J., S.L. Morris-Natschke, K.L. Meyer, F. Gumus, J.R. Suries, K.S. Ishaq, L.S. Kucera, N.Iyer, C.A. Wallen, S. Piantadosi, and E.J. Modest.1991, "Synthesis of new ether lipid nucleoside conjugates and evaluation of their anti-HIV activity", J.Med Chem.34:1408,1414; Hosteller, K.Y., D.D.Richman, D.A.Carson, L.M.Stuhmiller, G.M.T.van Wijk, and H. van den Bosch. 1992, "Dimyristoylglycerol, a lipid prodrug of 3'-deoxythymidine diphosphate, greatly enhanced the response to CEM and HT4 Inhibition of Human Immunodeficiency Virus Type 1 Replication in -6C Cells", Antimicrob.Agents Chemother. Synthesis and antiretroviral activity of phospholipid analogs of glycosides and other antiviral nucleosides", J.BioL Chem.265:61127. the

Non-limiting examples of U.S. patents disclosing suitable lipophilic substituents or lipophilic formulations that can be covalently bonded to nucleosides, preferably at the 5'-OH position of nucleosides, include U.S. Patent Nos. 5,149,794 (1992 22 September 1993, Yatvin et al); 5,194,654 (March 16, 1993, Hostetler et al); 5,223,263 (June 29, 1993, Hostetler et al); 5,256,641 (October 26, 1993, Yatvin et al); 5,411,947 (May 2, 1995, Hostetler et al); 5,463,092 (October 31, 1995, Hostetler et al); 5,543,389 (August 6, 1996, Yatvin et al); 5,543,390 (August 6, 1996, Yatvin et al) ; 5,543,391 (August 6, 1996, Yatvin et al); and 5,554,728 (September 10, 1996; Basava et al), the entire contents of which are incorporated herein by reference. Foreign patents that disclose lipophilic substituents or lipophilic preparations that can be attached to the nucleosides of the present invention include WO 89/02733, WO 90/00555, WO 91/16920, WO 91/18914, WO 93/00910, WO 94 /26273, WO 96/15132, EP 0350287, EP 93917054.4, and WO 91/19721. the

Non-limiting examples of nucleotide prodrugs are described in the following literature: Ho, DHW (1973) "Kinase and deaminase distribution of 1β-D-arabinofuranosylcytosine in human and mouse tissues", Cancer Res.33, 2816-2820; Holy, A. (1993) "Extremely phosphorous-modified nucleotide analogues", see: De Clercq (editor), Advances in Antiviral Drug Design Vol.1, JAI Press, pp.179 -231; Hong, CI, Nechaev, A., and West, CR (1979a) "Synthesis and antitumor activity of hydrocortisone and 1-β-D-arabinofuranosylcytosine conjugates of cortisone ", Bicohem. Biophys. Rs. Commun. 88, 1223-1229; Hong, CI, Nechaev, A., Kirisits, AJ Buchheit, DJ and West, CR (1980) "Nucleoside conjugates as potential antineoplastic agents , 3. Synthesis and antitumor activity of 1-(β-D-arabinofuranosyl)cytosine conjugates of corticosteroids and selected lipophilic alcohols", J.Med.Chem.28, 171-177; Hosteller, KY, Stuhmiller, LM, Lenting, HBM van den Bosch, H. and Richman J. Biol. Chem. 265, 6112-6117; Hosteller, KY, Carson, DA and Richman, DD (1991); "Phosphatidyl azide Thymidine: a mechanism of antiviral activity in CEM cells", J. Biol. Chem. 266, 11714-11717; Hosteller, KY, Korba, B. Sridhar, C., Gardener, M. (1994a) "Phosphatidyl- Antiviral activity of dideoxycytidine in hepatitis B-infected cells and enhanced hepatic uptake in mice", Antiviral Res. 24, 59-67; Hosteller, KY, Richman, DD, Sridhar. CNFelgner, PLFelgner , J., Ricci, J., Gardener, MFSelleseth, DW and Ellis, MN (1994b) "Phosphatidyl azidothymidine and phosphatidyl-ddC: uptake in mouse lymphoid tissue and in human immunodeficiency virus infection Evaluation of Antiviral Activity in Cells and in Rauscher Leukemia Infected Mice", Antimicrobial Agents Chemother.38, 2792-2797; Hunston, RN, Jones, AAM, McGuigan, C., Wal ker, RT, Balzarini, J., and DeClercq, E. (1984) "Synthesis and biological properties of some cyclic phosphate triesters derived from 2'-deoxy-5-fluorouridine", J. Med Chem. 27, 440-444; Ji, YH, Moog, C., Schmitt, G., Bischoff, P., and Luu, B. (1990); "7-beta-hydroxycholesterol and pyrimidine nucleosides as potential antineoplastic agents." Monophosphates: Synthesis and Preliminary Evaluation of Antitumor Activity", J. Med Chem. 33 2264-2270; Jones, AS, McGuigan, C., Walker, RT, Balzarini, J. and DeClercq, E. (1984)" Synthesis, properties and biological activity of some nucleoside cyclophosphamides", J. Chem. N) Synthesis of amino acid derivatives", Coll.Czech.Chem.Comm.39, 363-968; Kataoka, S., Imai, J., Yamaji, N., Kato, M., Saito, M., Kawada, T. and Imai, S. (1989) "Alkylated cAMP derivatives; selective synthesis and biological activity", Nucleic Acids Res, Sym. Ser. 21, 1-2; Kataoka, S., Uchida, "(cAMP ) Benzyl and Methyl Triesters", Heterocycles 32, 1351-1356; Kinchington, D., Harvey, JJ, O'Comor, TJ, Jones, BCNM, Devine, KG, Taylor-Robinson D., Jeffies, DJ, and McGuigan , C. (1992) "Comparison of antiviral effects of phosphoramidate and phosphoramidate derivatives of zidovudine against HIV and ULV in vitro", Antiviral Chem.Chemother.3, 107-112; Kodmna, K. , Morozumi, M., Saithoh, KI, Kuninaka, H., Yosino, H. and Saneyoshi, M. (1989) "1-β-D-arabinofuranosylcytosine-5'-stearyl phosphate Antitumor activity and pharmacology; an orally active derivative of 1-beta-D-arabinofuranosylcytosine", Jpn. J. Cancer Res. 80, 679-685; Korty, M. and Engels, J. (1979) "Effects of adenosine- and guanosine 3', 5' phosphates and benzyl esters on the ventricular myocardium of guinea pigs", Naunyn -Schmiedeberg's Arch.Pharmacol.310, 103-111; Kumar, A., Goe, PL, Jones, AS Walker, RT Balzarini, J. and DeClereq, E. (1990) "Synthesis of some cyclic phosphoramidate nucleoside derivatives and Biological evaluation", J. Med. Chem, 33, 2368-2375; LeBec, C. and Huynh-Dinh, T. (1991) "Phosphate triester derivatives of 5-fluorouridine, an arabinosyl as anti- Synthesis of cytarabine as a procancer drug", Tetrahedron Lett. 32, 6553-6556; Lichtenstein, J., Barner. HD and Cohen, SS (1960) "Metabolism of exogenous nucleotides from Escherichia coli. ", J. Biol. Chem. 235, 457-465; Lucthy, J., Von Daeniken, A., Friederich, J. Manthey, B., Zweifel, J., Schlafter, C. and Bem, MH (1981) "Synthesis and Toxicity of Natural Cyanoepithioalkanes", Mitt.Geg.Lebensmittelunters.Hyg.72, 131-133 (Chem.Abstr.95, 127093); ) "Synthesis and biological evaluation of some phosphotriesters of the antiviral drug Ara", Nucleic Acids Res. 17, 6065-6075; McGuigan, C., Devine, KG, O'Connor, TJ, Galpin, SA, Jeffries, DJ and Kinchington, D. (1990a) "Synthesis and evaluation of some new phosphoramidate derivatives of the anti-HIV compound 3'-azido-3'-deoxythymidine (AZT)", Antiviral Chem.Chemother.I 107-113; McGuigan, C., O'Connor, TJ, Nicholls, SRNickson, C., and Kinchington, D. (1990b) "Synthesis and Antibiotics of Some Novel Substituted Dialkyl Phosphate Derivatives of AZT and ddCyd HIV Activity", Antiviral Chem. Chemother. 1, 355-360; McGuigan, C., Nicholls, SR, O'Connor, TJ, and Kinchington, D. (1990c) "3'-Modifications as Potential Anti-AIDS Drugs Some new dialkyl phosphates of nucleosides Synthesis of Esters Derivatives", Antiviral Chem.Chemother.1, 25-33; McGuigan, C., Devin, KG, O' Cornnor, TJ, and Kinehington, D. (1991) "3'-Azido-3 Synthesis and anti-HIV activity of some haloalkyl phosphoramidate derivatives of '-deoxythymidine (AZT); strong activity of trichloroethylmethoxyalanyl compounds", Antiviral Res. 15, 255-263; McGuigan , C., Pathirana, RN, B, J. and DeCiercq, E. (1993 b) "Intracellular transport of biologically active AZT nucleotides by aryl phosphate derivatives of AZT", J. Med Chem. 36, 1048-1052.

The alkyl hydrogen phosphate derivatives of the anti-HIV agent AZT may be less toxic than the parent nucleosides. AntiViral Chem.Chemother.5, 271-277; Meyer, RB, Jr., Shuman, DA and Robins, RK (1973) "Synthesis of purine nucleoside 3',5'-cyclocyanophosphate", Tetrahedron Lett. 269-272; Nagyvary, J. Gohil, RN, Kirchner, CR and Stevens, JD (1973) "Studies on neutral esters of cyclic AMPs", Biochem. Biophys. Res. Commun. 55, 1072-1077; Namane, A .Gouyette, C., Fillion, MP, fillion, G. and HuynhDinh, T. (1992) "Improvement of brain transport of AZT with glucosyl phosphotriester prodrugs", J.Med Chem.35, 3039-3044; Nargeot, J. Nerbome, JMEngels, J. and Leser, HA (1983) Natl. Acad. Sci. USA80, 2395-2399; Nelson, KA, Bentrude, WGStser, WN and Hutchinson, JP (1987) "Nucleoside rings The problem of distorted equilibrium of the phosphate ring of the 3′,5′ monophosphate. ¹ H NMR and X-ray crystallography studies of the diastereoisomers of the 3′,5′-monophosphate of the thymidine phenyl ring”, J. Am.Chem.Soc.109, 4058-4064; Nerbonne.JM, Richard, S., Nargeot, J. and Lester, HA (1984) "New photoactivatable cyclic nucleotide production in terms of cyclic AMP and cyclic GMP concentrations Intracellular skipping", Nature 301, 74-76; Neumann, JM, Herve, M., Debouzy, JC, Guerra, FI, Gouyette, C., Dupraz, B. and Huyny-Dinh, T. (1989)" Glucosylphospholipid synthesis of thymidine and its transmembrane transport by NMR", J.Am.Chem.Soc.111, 4270-4277; Ohno, R., Tatsumi, N., Hirano, M., Imai , K. Mizoguchi, H., Nakamura, T., Kosaka, M., Takatuski, K., Yajnaya, T., Toyarna K., Yoshida, T., Masaoka, T., Hashimoto, S., Ohshima, T. ., Kimura, I., Ywnada, K. and Kimura, J. (1991) "Oral 1-β-D-arabinosyluranylcytosine-5'-stearyl phosphate therapy Myelodysplastic Syndromes", Oncology 48, 451-455. Palomino, E., Kessle, D. and Horwitz, JP (1989) "A dihydropyridine carrier system for sustained transport of 2',3' dideoxynucleosides to the brain", J. Med Chem. 32, 22- 625; Perkins, RM, Barney, S. Wittrock, R., Clark, PH, Levin, R. Lambert, DM, Peneway, SR, Serafinowska, HT, Bailey, SM, Jackson, S., Hamden, MR. Ashton, R. , Sutton, D., Harvey, JJ and Brown, AG (1993) ""BRL47923 and its oral prodrug SB203657A anti-rauscher murine leukemia virus infection activity in mice", Antiviral Res.20(Suppl.I).84; Piantadosi, C., Marasco, CJ, Jr., Norris-Natschke, SL, Meyer, KL, Gumus, F., Surles, JR, Ishaq, KS, Kucera, LSlyer, N., Wallen, CA, Piantadosi, S. . and Modest, EJ (1991) "the synthesis of new ether lipid nucleoside conjugates and the evaluation of anti-HIV-1 activity", J.Med Chem.34,1408-1414; Pompon, A., Lefebvre, I. , Imbach, JL, Kahn, S. and Farquhar, D. (1994). "Mono- and bis-(pivaloyloxymethoxymethyl) of azidothymidine-5'-monophosphate in cell extracts and tissue culture media Decomposition pathway of base) ester; application of closed circuit ISRP-clean HPLC technique", Antiviral Chem Chemother.5, 91-98; Postemark, T. (1974) "Cyclic AMP and Cyclic GMP", Annu.Rev.Pharmacol.14 , 23-33; Prisbe, EJ, Martin, JCM, McGhee, DPC, Barker, MF, Smee, DFDuke, AE, Matthews, TR and Verheyden, JPJ (1986) "9-[(1,3-dihydroxy-2 -propoxy)methyl]guanine phosphoric acid and phosphonic acid derivatives synthesis and anti-herpes virus activity", J.Med.Chem.29,671-675; Pucch, F., Gosselin, G., Lefebvre, I., Pompon, a., Aubertin, AMDim, and Imbach, JL (1993) "Intracellular transport of nucleoside monophosphates by a reductase-mediated activation method" , Antivral Res. 22, 155-174; Pugaeva, VP. Klochkeva, SI, Mashbits, FD and Eizengart, RS (1969). "Toxicity evaluation and health scales of thiolane in industrial settings", Gig.Trf. Prof. Zabol. 14, 4748 (Chem. Abstr. 72, 212); Robins, RK (1984) "The Potential of Nucleotide Analogues as Retroviral and Tumor Suppressors", Pharm. Res. 11-18; Rosowsky , A., Kim.SH, Ross and J.Wick, MM (1982) "The lipophilic 5' (alkyl phosphate) ester of 1-β-D-arabinosylcytosine and its N4-acyl and 2.2'-Anhydro-3'O-acyl derivatives as potential prodrugs", J. Med Chem. 25, 171-178; Ross, W. (1961) "A stepwise loading device for aromatic nitrogen with basic side chains Increased sensitivity of mustard after glucose pretreatment", Biochem.Pharm.8, 235-240; Ryu, EK, Ross, RJ, Matsushita, T., MacCoss, M., Hong, CI and West, CR (1982)." Phospholipid nucleoside conjugates. 3. Synthesis and preliminary biological evaluation of 1-β-D-arabinofuranosylcytosine 5' diphosphate [-], 2-diacylglycerol", J. Med Chem. 25, 13221329; Saffhill, R. and Huine, WJ (1986) "Degradation of 5-iododeoxyuridine and 5-bromoethoxyuridine by serum of different origins and results of incorporation into DNA with these compounds", Chem.Biol.Interact.57, 347- 355; Saneyoshi, M., Morozumi, M., Kodama, K., Machida, J., Kuninaka, A., and Yoshino, H. 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Examples of advantageous phosphate prodrugs are S-acyl-2-thioethyls, also known as "SATE ".

II. Combination and Alternation Therapy

It is recognized that drug-resistant variants of HIV and HBV can emerge during prolonged treatment with antiviral agents. Drug resistance arises most often through mutations in genes encoding enzymes for viral replication, and in the case of HIV, most commonly reverse transcriptase, protease or DNA polymerase, and in the case of HBV, DNA polymerase. More recently, it has been shown that the effect of a drug against HIV infection can be prolonged, increased or maintained by combining or alternating the compound with a second, and perhaps a third, antiviral compound causing a different mutation from the main drug. Alternatively, the pharmacokinetics, biodistribution or other parameters of the drug may be altered by such combination or alternation therapy. In conclusion, combination therapy is generally preferred over alternating therapy because of the multiple stimulatory stresses it causes on the virus. the

In one embodiment, the second antiviral agent used to treat HIV may be a reverse transcriptase inhibitor (an "RTI"), which may be a synthetic nucleoside (an "NRTI") or a non-nucleoside compound ( a "NNRTI"). In one embodiment, for HIV, the second (or third) antiviral agent may be a protease inhibitor. In another embodiment, the second (or third) may be a pyrophosphate analog or a fusion binding inhibitor. For in vitro and in vivo resistance data for some antiviral compounds, see Schinazi et al., Mutations in Retroviral Genes Associated with Drug Resistance, International Antiviral News, 1997. the

Preferred compounds for combined or alternating treatment of HBV include 3TC, FTC, L-FMAU, interferon, β-D-dioxolanyl-guanine (DXG), β-D-dioxolane 2,6-diaminopurine (DAPD) and β-D-dioxolanyl-6-chloropurine (ACP), famciclovir, penciclovir, BMS-200475, bis pom PMEA (adefovir, dipivoxil ); lobucavir, ganciclovir and ribavirin. the

Preferred examples of antiviral agents that may be combined or alternately treated with the compounds disclosed herein include cis-2-hydroxymethyl-5-(5-fluorocytosin-1-yl)-1,3-oxathiolane alkane (FTC); (-)-enantiomer of 2-hydroxymethyl-5-(cytosin-1-yl)-1,3-oxathiolane (3TC); Carbopol , Acyclovir, Foscarnet, Interferon, AZT, DDI, DDC, D4T, CS-87 (3′-azido-2′, 3′-dideoxy-uridine) and β-D-diox Oleolane nucleosides such as β-D-dioxolanyl-guanine (DXG), β-D-dioxolanyl-2,6-diaminopurine (DAPD) and β- D-dioxolanyl-6-chloropurine (ACP), MKC-442 (6-benzyl-1-(ethoxymethyl)-5-isopropyluracil. 

Preferred protease inhibitors include crixivan (Merck), nelfinavir (Agouron), ritonavir (Abbott), saquinavir (Roche), DMP-266 (Sustiva, Feveren) and DMP-450 (DuPont Merck). the

A more comprehensive list of compounds that can be administered in combination or alternately with any of the disclosed nucleosides includes (1S,4R)-4-[2-amino-6-cyclopropylamino)-9H-purin-9-yl]- 2-Cyclopentene-1-methanol succinate ("1592", a Carbopol analog; GlaxoWellcome); 3TC: (-)-B-L-2′,3′-dideoxy-3′-thia Cytidine (GlaxoWellcome); a-APA R18893: a-Nitro-anilino-phenylacetamide; A-77003; C2 symmetric protease inhibitor (Abbott); A-75925: C2 symmetric protease inhibitor (Abbott) ; AAP-BHAP: bis-heteroarylpiperazine analog (Upjohn); ABT-538: C2 symmetric protease inhibitor (Abbott); AzddU: 3'-azido-2',3'-dideoxyuridine; AZT: 3′-Azido-3′-deoxythymidine (GlaxoWellcome); AZT-p-ddI: 3′-Azido-3′-deoxythymidine-(5′,5′)-2′ , 3′-dideoxyinosine nucleotide (Ivax); BHAP: bis-heteroarylpiperazine; BILA 1906: N-{1S-[[[3-[2S-{(1,1-dimethyl Ethyl)amino]carbonyl}-4R-]3-pyridylmethyl)thio]-1-piperidinyl]-2R-hydroxy-1S(phenylmethyl)propyl]amino]carbonyl]-2- Methylpropyl}-2-quinolinecarboxamide (Bio Mega/Boehringer-Ingelheim); BILA 2185: N-(1,1-Dimethylethyl)-1-[2S-[[2-2,6 -Dimethylphenoxy)-1-oxoethyl)amino]-2R-hydroxy-4-phenylbutyl]-4R-pyridylthio)-2-piperidinecarboxamide (BioMega/Boehringer- Ingelheim); BM+51.0836: Thiazolo-isoindolinone derivatives; BMS 186, 318: Aminodiol derivatives HIV-1 protease inhibitors (Bristol-Myers-Squibb); d4API: 9-[2, 5-Dihydro-5-(phosphorylmethoxy)-2-furyl]adenine (Gilead); d4C: 2',3'-didehydro-2',3'-dideoxycytidine; d4T : 2', 3'-didehydro-3'-deoxythymidine (Bristol-Myers-Squibb); ddC; 2', 3'-dideoxycytidine (Roche); ddI: 2', 3'-di Deoxyinosine (Bristol-Myers-Squibb); DMP-266: 1,4-dihydro-2H-3,1-benzo-oxazin-2-one; DMP-450: {[4R-(4-a, 5-a, 6-b, 7-b)]-hexahydro- 5,6-bis(hydroxyl)-1,3-bis(3-amino)phenyl]methyl)-4,7-bis(phenylmethyl)-2H-1,3-diazepane En-2-one}-dimesylate (Avid); DXG: (-)-β-D-dioxolaneguanosine (Triangle); EBU-dM: 5-ethyl-1-ethyl Oxymethyl-6-(3,5-dimethylbenzyl)uracil; E-EBU: 5-ethyl-1-ethoxymethyl-6-benzyluracil; DS: dextran sulfate Sugar; E-EPSeU: 1-(ethoxymethyl)-(6-phenylhydroselenyl)-5-ethyluracil; E-EPU: 1-(ethoxymethyl)-(6- Phenylthio)-5-ethyluracil; FTC: β-2',3'-dideoxy-5-fluoro-3'-thiacytidine (Triangle); HBY097: S-4-isopropoxy Carbonyl-6-methoxy-3-(methylthio-methyl)-3,4-dihydroquinoxaline-2(1H)-thione; HEPT: 1-[(2-hydroxyethoxy) Methyl]-6-(phenylthio)thymine; HIV-1: human immunodeficiency virus type 1; JM2763: 1,1'-(1,3-propylene)-bis-1,4,8, 11-tetraazacyclotetradecane (JohnsonMatthey); JM3100: 1,1'-[1,4-phenylenebis-(methylene)]bis-1,4,8,11-tetraazacyclo Tetradecane (Johnson Matthey); KNI-272: tripeptide containing (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid; L-697,593; 5-ethyl-6- Methyl-3-(2-phthalimido-ethyl)pyridin-2(1H)-one; L-735,524: Hydroxy-aminopentanecarboxamide HIV-1 protease inhibitor (Merck); L -697,661: 3-{[(-4,7-dichloro-1,3-benzo-oxazol-2-yl)methyl]amino}-5-ethyl-6-methylpyridine-2( 1H)-ketone; L-FDDC: (-)-β-L-5-fluoro-2',3'-dideoxycytidine; L-FDOC: (-)-β-L-5-fluoro-diox Heterocyclopentylcytosine; NMC442: 6-Benzyl-1-ethoxymethyl-5-isopropyluracil (I-EBU; Triangle/Mitsubishi); Nevirapine: 11-cyclopropyl-5,11 -Dihydro-4-methyl-6H-dipyrido1[3,2-b:2',3'-e]diazepine-6-one (Boehringer-Ingelheim); NSC648400:1 -Benzyloxymethyl-5-ethyl-6-(α-pyridylthio)uracil (E-BPTU); P9941: [2-pyridylacetyl-IlePheAla-y(CHOH)]2 (Dupont Merck ); PFA: phosphonoformate (sodium phosphonoformate ; Astra); PMEA: 9-(2-phosphorylmethoxyethyl) adenine (Gilead); PMPA: (R)-9-(2-phosphorylmethoxypropyl) adenine (Gilead); Ro 31-8959: Hydroxyethylamine derivative HIV-1 protease inhibitor (Roche); RPI-312: Peptidyl protease inhibitor, 1-[(3s)-3-(n-α-benzyloxycarbonyl)-1- Asparaginyl)-amino-2-hydroxy-4-phenylbutyryl]-n-tert-butyl-1-proline amide; 2720: 6-chloro-3,3-dimethyl 4-(iso Propyleneoxycarbonyl)-3,4-dihydro-quinoxaline-2(1H)thione; SC-52151: Hydroxyethyl-urea isostere protease inhibitor (Searle); SC-55389A: Hydroxyethyl - Urea isostere protease inhibitor (Searle); TIBO R82150: (+)-(5S)-4,5,6,7-tetrahydro-5-methyl-6-(3-methyl-2- Butenyl)imidazo[4,5,1-jk][1,4]-benzodiazepine-2(1H)-thione (Janssen); TIBO 82913: (+)-( 5S)-4,5,6,7-tetrahydro-9-chloro-5-methyl-6-(3-methyl-2-butenyl)imidazo[4,5,1jk]-[1, 4] Benzo-diazepine-2(1H)-thione (Janssen); TSAO-m3T: [2′,5′-bis-O-(tert-butyldimethylsilyl) -3'-spiro-5'-(4'-amino-1',2'-oxathiol (thiole)-2',2'-dioxide)]-b-D-pentofuranosyl-N3- Methylthymine; U90152: 1-[3-[(1-methylethyl)-amino]-2-pyridyl]-4-[[5-[(methylsulfonyl)-amino]-1H- Indol-2-yl]carbonyl]piperazine; UC: thioanilide derivative (Uniroyal); UC-781=N-[4-chloro-3-(3-methyl-2-butenyloxy) Phenyl]-2-methyl-3-furylthiocarbamide; UC-82=N-[4-chloro-3-(3-methyl-2-butenyloxy)phenyl]-2-methyl yl-3-thiophene thiocarboxamide; VB 11,328: Hydroxyethyl-sulfonamide protease inhibitor (Vertex); VX-478: Hydroxyethyl-sulfonamide protease inhibitor (Vertex); XM 323: Cyclic urea Protease inhibitors (Dupont Merck). the

Combination therapy for proliferative disorders

In another embodiment, when used as antiproliferative agents, these compounds may be used in combination with another compound that increases the therapeutic effect, so-called another compound including but not limited to antifolates, 5-fluoropyrimidine ( including 5-fluorouracil), cytidine analogs such as β-L-1,3-dioxolyl cytidine or β-L-1,3-dioxolanyl 5-fluorocytidine, Antimetabolites (including purine antimetabolites, arabinoside, fudarabine, floxuridine, 6-mercaptopurine, methotrexate, and 6-thioguanine), hydroxyurea, mitotic inhibitors (including CPT-11 , etoposide (VP-21), paclitaxel and vinca alkaloids such as vincristine and vinblastine, alkylating agents (including but not limited to busulfan, chlorambucil, cyclophosphamide, heterocyclic Phosphoramides, nitrogen mustards, melphalan, and thiotepa), nonclassical alkylating agents, platinum-containing compounds, bleomycin, antineoplastic antibiotics, anthracyclines such as doxorubicin and dannomycin, anthracenediones class, topoisomerase II inhibitors, hormone agents (including but not limited to corticosteroids (dexamethasone, prednisone, and methylprednisone), androgens such as fluoxymesterone and methyltestosterone, estrogens such as diethylstilbestrol , antiestrogens such as tamoxifen, LHRH analogues such as lipramide, antiandrogens such as flutamide, aminoglutethimide, megestrol acetate and medroxyprogesterone), asparaginase, carmo Stine, rolomustine, hexamethyl-melamine, dacarbazine, mitotane, streptozocin, cisplatin, carboplatin, levamisole and leucovorin. The compounds of the present invention can also be used with enzyme therapeutics and immune system Modulators such as interferon, interleukin, tumor necrosis factor, macrophage colony-stimulating factor, and colony-stimulating factor are used in combination. 

III. Methods of preparing active compounds

In one embodiment of the present invention there is provided a diastereoselective reaction to introduce fluorine onto the sugar moiety of a novel nucleoside analog. This synthesis can be used to prepare purine and pyrimidine derivatives. A key step in the synthetic route is the chiral, non-carbohydrate sugar ring precursor (4S)-5-(protected-oxy)-pentan-4-lactone, e.g., (4S)-5-(tert Butyldiphenylsiloxy)pentan-4-methyl ester 4 uses electrophilic fluorine sources including, but not limited to, N-fluoro-(bis)benzenesulfonimide 5 . This relatively new N-fluorosulfonimide reagent was first opened by Barnette in 1984, and has since been refined and used as a convenient and highly reactive electrophilic fluorine (Barnette, W.E.J.Am.Chem.Soc.1984, 106 , 452.; Davis, F.A.; Han; W., Murphy, C.K.J.Org.Chem.1995, 60, 4730; Snieckus, V.; Beaulieu, F.; Mohri, K.; Han, W.; Murphy, C.K.; Davis, F.A. Tetrahedron Lett. 1994, 35(21), 3465). These reagents are most commonly used to transport fluorine to nucleophiles such as enolates and metallated aromatic compounds (Davis, F.A.; Han; W., Murphy, C.K.J. Org. Chem. 1995, 60, 4730). Specifically, N-fluoro-(bis)benzenesulfonimide (NFSI) is an air-stable, easy-to-handle solid that is stereoselective for silyl-protected enolate of lactone 4 with fluoro have sufficient steric hindrance. As a non-limiting example of this approach, the synthesis of fluorinated lactone 6 and its use as a common intermediate in the synthesis of some novel α-2'-fluoronucleosides is detailed below. Based on the present description, one of ordinary skill in the art can routinely modify this method as necessary to accomplish the required purpose and prepare the desired compound. the

The precursor (4S)-5-(protected-oxy)-pentan-4-lactone, such as (4S)-5-(tert-butyldiphenylsilane Oxy)-pentan-4-lactone fluorination. Other sources of electrophilic fluorine include N-fluorosulfamic acids (Differding et al., Tet.Lett.Vol.29, No.47pp.6087-6090 (1988); Chemical Reviews, 1992, Vol92, No.4( 517)), N-fluoro-O-benzenedisulfonimide (Tet.Lett.Vol.35, pages 3456-3468 (1994), Tet Lett.Vol35.No.20, pages 3263-3266 (1994)) ; J.Org.Chem.1995,60,4730-4737), 1-fluoroethylene and synthetic equivalents (Matthews, Tet.Lett.Vol.35, No.7, pages 1027-1030 (1994); Allied Signal , Inc., Buffalo Research Laboratory, Buffalo, New York sold Accufluor fluorinating reagent (NFTh(1-fluoro-4-hydroxyl-1,4-diazo-bicyclo[2.2.2]octanebis(tetrafluoro borate)), NFPy (N-fluoropyridine_pyridine heptafluorodiborate) and NFSi (N-fluorobenzenesulfonimide); electrophilic fluorinating reagents sold by Aldrich Chemical Company, Inc., including N-fluoropyridine_salt ((1-fluoro-2,4,6-collidine-trifluoromethanesulfonate, 3,5-dichloro-1-fluoropyridine-trifluoromethanesulfonate, 1 -fluoropyridine_trifluoromethanesulfonate, 1-fluoropyridine_tetrafluoroborate and 1-fluoropyridine_heptafluorodiborate), see also J.Am.Chem.Soc., Vol 112, No.23 1990); N-fluorosulfonimides and amides (N-fluoro-N-methyl-p-toluenesulfonamide, N-fluoro-N-propyl-p-toluenesulfonamide and N-fluoro benzenesulfonimide); N-fluoro-quinine butyl fluoride (J.Chem.Soc.Perkin Trans I 1988, 2805-2811); perfluoro-2,3,4,5-tetrahydropyridine and perfluoro -(1-methylpyrrolidine), Banks, Cheng and Haszeldine, Heterocyclic polyfluoro-compounds Part II (1964); 1-fluoro-2-pyridone, J.Org.Chem., 1983 48, 761 -762; Quaternary entity center with fluorine atom (T.Chem.Soc.Perkin.Trans. pp. 221-227 (1992)); N-fluoro-2,4,6-pyridine_trifluoromethanesulfonate , Shimizu, Tetrahedron Vol 50(2), pp. 487-495 (1994); N-fluoropyridine-pyridine heptafluorodiborate, J.Org.Chem.1991, 56, 5962-596 4. Umemoto et al., Bull.Chem.Soc.Jpn., 64 1081-1092(1991); N-fluoroperfluoroalkylsulfonylimides, J.Am.Chem.Soc., 1987, 109, 7194 -7196; Purrington et al., Lewis acid-mediated fluorination of aromatic substrates, J. Org. Chem. 1991, 56, 142-145.

A significant advantage of this approach is the ability to use the "natural" (1a) D or "unnatural" (1b) L enantiomer of the nucleoside, respectively, by appropriate choice of the L- or D-glutamic acid starting material, respectively. the

Lactone 4 was synthesized from L-glutamic acid by the route shown in Scheme 1 as described by Ravid et al. (Tetrahedron 1978, 34, 1449) and Taniguchi et al. (Tetrahedron 1974, 30, 3547). the

plan 1

The enolate of lactone 4, prepared with LiHMDS in THF at -78°C, is known to be stable. Several syntheses have been performed with this enolate, including the addition of electrophiles such as diphenyldiselenide, diphenyldisulfide and alkyl halides in high yields (Liotta, D.C.; Wilson, L.J. Tetrahedron Lett. 1990, 31(13), 1815; Chu, C.K.; Babu, J.R.; Beach, J.W.; , H.; Ebata, T.; Koseki, K.; Matsushita, H.; Naoi, Y.; ltoh, K. Chem. Lett. 1990, 1459). However, addition of a THF solution of 5 to the enolate of 4 gave the desired monofluorinated product 6 in poor yields. Some by-products were formed including the presumed difluorolactone which could not be separated from other impurities. To this end, the order of reagent addition was changed and lactone 4 and NFSi5 were dissolved together in THF and cooled to −78 °C. Slow addition of LiHMDS gave the only product besides a small amount of unreacted starting material (Scheme 1). the

Reaction 1

After purification by silica gel column chromatography and crystallization, flulide 6 can be obtained in a yield of 50-70%. This reaction yielded a single diastereomer of 6, presumably due to the interaction of the sterically hindered TBDPS group and the bulkier fluorinated reagent 5. By comparison of previously published NMR data and X-ray crystallographic examination of its enantiomer 20, fluorolactone 6 was identified as the alpha or "down" fluoroisomer. the

The lactone 6 was converted to the anomer acetate 8 as shown in Scheme 2. It should be noted that the ortho-hydroxy internal ether 7 exists only as the β anomer, whereas the acetate 8 exhibits no NMR detectable α anomer, as reported by Niihata et al. (Bull. Chem. Soc. Jpn. 1995, 68, 1509). the

Scenario 2

Coupling of 8 with a silylated pyrimidine base was performed by the standard Vorbruggen method (Tetrahedron Lett. 1978, 15, 1339), using TMS triflate as the Lewis acid. Alternatively, any other Lewis acid known to condense bases and carbohydrates to form nucleosides may be used, including tin chloride, titanium chloride, and other tin or titanium compounds. Several bases were successfully coupled in high yields of 72-100% after column chromatography purification (Scheme 2, Table 1). the

Reaction 2

Table 1. Glycosylation of substituted pyrimidines with 8

Proton NMR indicated that the ratio of beta and alpha nucleoside anomers was about 2:1 in all cases. Silyl-protected nucleosides cannot be resolved into the separated anomers by column chromatography. However, after deprotection of the 5'-oxygen atom with _NH4F in methanol (Scheme 3), the α and β anomers were easily separated and are summarized in Table 2.

Reaction 3

Table 2. Deprotection of nucleosides

Classification of alpha or beta free nucleosides was based on the chemical shifts of the anomeric protons (Table 3) and the polarity of the nucleosides as observed by thin layer chromatography. A trend was observed for the α/β pairs of all free nucleosides, where the chemical shifts of the anomeric protons of the less polar compounds were clearly higher than those of the more polar compounds at higher fields. the

Table 3. Anomeric proton chemical shifts (ppm)

By comparing 18a (Niihata, S.; Ebata, T.; Kawakami, H.; Matsushida, H. Bull. Chem. Soc. Jpn. 1995, 68, 1509) and 18b (Aerschot, A.V.; Herdewijn, P.; Balzarini , J.; Pauwels, R.; De Clercq, E.J.MedChem.1989, 32, 1743), using previously published spectroscopic data and by X-ray crystallographic structure determination of 14b and 15b, to prove that the anomeric proton chemical shift and Absolute structural relationship. This finding is contrary to the usual trend for nucleosides, where the alpha anomer is generally the less polar of the two. Presumably in the "down" 2'-fluorinated nucleosides, the strong dipole of the C-F bond opposes the C-N anomer bond dipole in the β-isomer and reduces the dipolarity of the entire molecule. In contrast, the geometry of the α-anomer is such that the molecular dipole is reinforced by the addition of C-F and C-N bond dipoles. Thus, in the case of α-2'-fluoronucleosides, the α anomer is more polar than the β anomer. the

The alpha and beta anomers 17a and 17b could not be separated by column chromatography because the free amino group made the nucleoside travel too quickly on the silica gel. Therefore, N ⁴ acetylcytosine was required to prepare 11 and to resolve 16a and 16b. The ^N4 -acetyl group was quantitatively removed with ammonia in saturated methanol to give isolated 17a and 17b. When 5-fluorocytosine was used as the base (compound 10), anomers 15a and 15b were easily separated and no spot formation on silica gel was observed.

Of the ten nucleosides listed in Table 2, only 17b appears to be (Martin, JA; Bushnell, DI; Duncan, IB; Dunsdon, SJ; Hall, MJ; Machin, PJ; Merrett, JH; Parkes, KEB; Roberts, NA; Thomas, GJ; Galpin, SA; Kinchington, DJ Med. Chem.1990, 33(8), 2137; Zenchoff, GB; Sun, R; Okabe, MJ Org. Chem. .S.; Ebata, T.; Kawakami, H.; Matsushida, H. Bull. Chem. Soc. Jpn. 1995, 68, 1509) and 18b (Aerschot, AV; Herdewijn, P.; Balzarini, J.; Pauwels , R.; De Clercq, EJMed Chem.1989, 32, 1743) have been synthesized before. They have been synthesized from natural precursors (ie they are in the β-D configuration), as have some known 2'-β or "up" fluoronucleoside analogs ¹⁴ . β-L-2'-fluororibofuranosyl nucleosides do not appear to have been identified in the literature prior to the present invention.

Typically these molecules introduce fluorine by nucleophilic attack on anhydronucleosides (Mengel, R.; Guschlbauer, W. Angew. Chem., Int. Ed. Engl. 1978, 17, 525) or by adding trifluorinated diethylamino Sulfur (DAST) stereochemically fixed hydroxyl substitution or conversion to introduce fluorine (Herdewijn, P.; Aerschot, A.V.; Kerremans, L. Nucleosides Nucleotides, 1989, 8(1), 65). One of the advantages of the method of the present invention is that no hydroxyl groups are required for the introduction of fluorine. Thus, the method is not limited to natural nucleosides or sugars as starting materials, and enables the simple use of unnatural enantiomers of 2'-fluoronucleosides. the

Thus, several unnatural nucleosides were synthesized using this synthetic route using D-glutamic acid 19 as starting material (Scheme 3). Sugar ring precursor 20 was fluorinated as described above and coupled with various silylated bases (Table 4). the

Option 3

Table 4. Yields of unnatural nucleoside analogs

Option 4

The successful synthesis of 29, as shown in Scheme 4, utilized two classes of nucleosides. The first class is called 2',3'-dideoxy-2',3'-didehydro-2-2'-fluoro-nucleosides,30, while the second class is the "up"-fluoro or arabinosyl analogs, 31, as described in Scheme 5 below. the

Option 5

Compounds 30 and 31 can be synthesized from common intermediate 32, which can be obtained by selenylation of fluoroalkene sugar 29. the

Option 6

The selenated compound 32 can be converted to the "up" fluorinated analog 31 by reduction with Raney nickel. Alternatively, oxidation of selenide 32 with _NaIO4 or hydrogen peroxide followed by thermal elimination of this selenide intermediate afforded 30. These transformations have been well reported for non-fluorinated systems (Wurster, JA; Ph. D. Thesis, Emory University, 1995; Wilson, LJ; Ph. D. Thesis, Emory University, 1992).

Furthermore, the synthesis of enantiomers of nucleosides 30 and 31 was also possible since they were obtained from the enantiomer of 29. the

An alternative route to the preparation of the compound 2',3'-dideoxy-2',3'-didehydro-2'-fluoro-nucleoside represented by 30 is shown in Scheme 7. This route provides simple, direct access to such compounds with a wide range of silylated bases and has been successfully accomplished. the

Option 7

The silylated ketene acetal formed from 6 can be stereoselectively added to phenylselenium bromide to give compound 36 as a single isomer. Reduction and acylation of this compound proceeded smoothly and yielded 37 in two steps in high yield. The α-orientation of the phenylselenyl group made the subsequent glycosylation step stereoselective and completed the synthesis of the β-isomer of nucleoside 38 in good yield. Compound 38 can be oxidized with hydrogen peroxide in dichloromethane to give the elimination reaction product 39, but in our experience, it is only necessary to adsorb 38 on silica gel and let it stay for several hours, after which it can be obtained from the piston column in a near quantitative manner. The yield eluted. Removal of the protecting group of 39 as previously described afforded the final product 30 and yielded the nucleoside product in good yield (81%). the

Scheme 8

The series of chemical transformations used for the synthesis of 30 and 31 can also be used for the synthesis of 34 and 35. the

Experimental part

general method

N-Fluoro-(bis)benzenesulfonimide 5 was obtained from Allied Signal and used without purification. All other reagents were obtained from Aldrich Chemical Company and used directly without purification. Melting points were detected with a Thomas Hoover capillary melting point apparatus and were not calibrated. IR spectra were obtained with a Nicolet Impact400FT-IR spectrometer. ¹ H NMR and ¹ C NMR spectra were recorded on NT-360 or Varian 400 MHz chromatographs. TLC plates were silica gel 60F ₂₅₄ (0.25mm thick) purchased from EM Science. Flash chromatography was performed on silica gel 60 (230-400 mesh, ASTM) from EM Science. All reactions were performed in flame-dried glass reactors under a dry argon atmosphere. Solvent was removed by rotary evaporation. Elemental analysis was performed by Atlantic Microlab, Inc, Atlanta, GA.

(2S, 4R)-5-(tert-butyldiphenylsilyloxy)-2-fluoropenta-4-lactone (20) 

To the reaction flask was added (4R)-5-(tert-butyldiphenylsilyloxy)-pentan-4-lactone (20.0 g, 0.0564 mol, 1.0 eq.) in 250 mL of anhydrous THF and N-Fluoro-(bis)benzenesulfonimide (NFSi) 5 (17.80 g, 0.0564 mol, 1.0 eq.). This solution was cooled to -78°C, and 68.0 mL (0.0680 mol, 1.2 eq.) of LiHMDS in 1.0 MTHF was added dropwise within 1 hour. It was stirred at -78°C for an additional 2 hours, then allowed to warm to room temperature and stirred for a further 1 hour. After completion of the reaction, the reaction was quenched with 10 mL of saturated ammonium chloride solution. The mixture was diluted with 3 volumes of ether and poured into an equal volume of saturated sodium bicarbonate. The organic layer was washed again with saturated sodium bicarbonate and once with saturated sodium chloride. The organic layer was dried over magnesium sulfate, filtered and concentrated to a yellow oil. The oil was purified by silica gel column chromatography using a 30% ether/70% hexane solvent system. The resulting white solid was crystallized with hot hexane to obtain 13.04 g (62% yield) of a transparent crystalline solid: R _f (30% ether/70% hexane) = 0.26; mp 115-116°C.

1H NMR (360MHz, CDCl ₃ ) d7.63-7.60(m, 4H), 7.45-7.35(m, 6H), 5.49(dt, J=52.9 and 7.9Hz, 1H), 4.69(d, J=9.36Hz , 1H), 3.91(d, J=11.5Hz, 1H), 3.60(d, J=11.5Hz, 1H), 2.72-2.40(m, 2H), 1.05(s, 9H); ¹³ C NMR (100MHz, CDCl ₃ )d172.1 (d, J=20.5Hz), 135.5, 135.4, 132.3, 131.7, 130.1, 128.0, 127.9, 85.6 (d, J=186.6Hz), 77.3 (d, J=5.3Hz), 65.0 , 31.8 (d, J=20.5Hz), 26.7, 19.1; IR (thin film) 2958, 1796, 1252, 1192, 1111, 1016cm ^-1 ; HRMS[M+Li]C ₂₁ H ₂₅ O ₃ FSiLi theoretical value: 379.1717 . Found value: 379.1713. CHAFFS elemental analysis theoretical value: C, 67.71; H, 6.76. Found: C, 67.72; H, 6.78.

5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-(L)-erythron-furanose (21) 

To the reaction flask was added lactone 20 (12.12 g, 0.0325 mol, 1.0 eq.) and 240 mL of anhydrous THF. This solution was cooled to -78°C and 65 mL (0.065 mol, 2.0 eq.) of 1.0 M DIBALH in hexane was added dropwise over 30 minutes. And stirred at -78°C for 3 hours, then slowly added 2.93mL (0.163mol, 5.0eq.) of water to stop the reaction. The reaction was warmed to room temperature and stirred for 1 hour after which time a gelatinous clear solid formed throughout the flask. The reaction mixture was diluted with two volumes of diethyl ether and poured into an Erlenmeyer flask into an equal volume of saturated aqueous sodium potassium tartrate. Stir for 20 minutes until the emulsion is broken. The organic layer was separated and the aqueous layer was extracted 3 times with 250 mL of ether. The combined organic layers were dried over magnesium sulfate, filtered, and concentrated to a pale yellow oil. The product was purified by column chromatography on silica gel, eluting with a 6:1 hexane/ethyl acetate solvent system. The resulting clear oil was crystallized from boiling hexane to give 11.98 g (98% yield) of a white crystalline solid: _Rf (30% ether/70% hexane) = 0.33; mp 66-67°C. ¹ H NMR (360MHz, CDCl ₃ )d 7.68-7.66(m, 4H), 7.55-7.38(m, 6H), 5.39(t, J=7.6Hz, 1H), 4.99(dd, J=52.2 and 4.3Hz , 1H), 4.52(m, 1H), 3.88(dd, J=10.8 and 2.5Hz, 1H), 3.65(d, J=7.9Hz, 1H), 3.49(dd, J=7.9 and 1.8Hz, IM, 2.44-2.07 (m, 2H), 1.07 (s, 9H); ¹³ C NMR (100 MHz, CDCl ₃ )d 135.7, 135.5, 132.2, 132.1, 130.2, 130.0, 129.8, 127.9, 127.7, 99.8 (d, J= 31.1Hz), 96.6(d, J=178.3Hz), 79.4, 64.8, 29.9(d, J=21.2Hz), 26.8, 19.2; IR (film) 3423, 2932, 1474, 1362, 1113cm ^-1 ; HRMS theory Value [M+Li]C ₂₁ H ₂₇ O ₃ FSiLi: 381.1874. Found value: 381.1877. Elemental analysis theoretical value. C ₂₁ H ₂₇ O ₃ FSi: C, 67.35; H, 7.27, found value: C, 67.42; H , 7.31.

1-O-acetyl-5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-(L)-erythro-furanose (22) 

To the reaction flask was added lactol 21 (8.50 g, 0.0227 mol, 1.0 eq.) and 170 mL of anhydrous dichloromethane. Then DMAP (0.277 g, 0.00277 mol, 0.1 eq.) and acetic anhydride (13.5 mL, 0.143 mol, 6.3 eq.) were added and stirred overnight at room temperature. After the reaction was completed, the reaction was poured into saturated sodium bicarbonate solution. The organic layer was separated, and the aqueous layer was extracted 3 times with chloroform. The combined organic layers were dried over magnesium sulfate, filtered, and the solvent was removed to give a pale yellow oil. The oil was purified by column chromatography on silica gel, eluting with a 8:1 hexane/ethyl acetate solvent system to give 9.85 g (99% yield) of a clear, colorless oil: R _f (30% ether/70% hexane )=0.44; ¹ H NMR (360MHz, CDCl ₃ )d 7.69-7.67(m, 4H), 7.43-7.38(m, 6H), 6.30(d, J=10.4Hz, 1H), 5.06(d, J= 54.9Hz, 1H), 4.53(m, 1H), 3.81(dd, J=10.8 and 4.3Hz, 1H), 3.72(dd, J=10.8 and 4.3Hz, 1H), 2.38-2.12(m, 2H), 1.89(s, 3H), 1.07(s, 9H); ¹³ C NMR (100MHz, CDCl ₃ )d 169.4, 135.6, 135.5, 133.2, 133.1, 129.8, 129.7, 127.8, 127.7, 99.3(d, J=34.1Hz ), 95.5 (d, J=178.2Hz), 81.4, 65.3, 31.6 (d, J=20.5Hz), 26.8, 21.1, 19.3; IR (film) 3074, 2860, 1750, 1589, 1229, ^1113cm-1 ; HRMS theoretical value [M-OCOCH ₃ ]C ₂₁ H ₂₆ O ₂ FSi: 357.1686. Measured value: 357.1695. Elemental analysis theoretical value. C ₂₃ H ₂₉ O ₄ FSi: C, 66.32; H, 7.02. Measured value: C, 66.30; H, 7.04.

A representative procedure for the coupling of a silylated base to 22: (L)-5'-O-(tert-butyldiphenylsilyl)-2',3-dideoxy-2'-fluoro-5 - Flucytidine (25)

To a flask equipped with a short-necked distillation head, add 5-fluorocytosine (2.01 g, 15.6 mmol, 5.0 eq), 35 mL of 1,1,1,3,3,3-hexamethyldisilazane and catalyst amount (about 1 mg) of (NH ₄ ) ₂ SO ₄ . The white suspension was heated to boiling for 1 hour until the base was silylated and the reaction solution became clear. Excess HMDS was distilled off and the oily residue was evacuated for 1 hour to remove the last traces of HMDS. The resulting white solid was dissolved in 5 mL of anhydrous 1,2-dichloroethane under argon atmosphere. To this clear solution was added a solution of acetate 22 (1.30 g, 3.12 mmol, 1.0 eq.) in 5 mL of anhydrous 1,2-dichloroethane. Trimethylsilyl trifluoromethanesulfonate (3.32 mL, 17.2 mmol, 5.5 eq.) was added thereto at room temperature. The reaction was monitored by TLC (10% methanol/90% dichloromethane) and completion was observed at 4 hours. The reaction mixture was poured into saturated sodium bicarbonate. Then, the organic layer was separated, and the aqueous layer was extracted 3 times with chloroform. The combined organic layers were dried over magnesium sulfate, filtered and the solvent was removed to give a white foam. This compound was purified by column chromatography on silica gel using a gradient solvent system from 100% dichloromethane to 10% methanol in dichloromethane. 1.51 g of this compound were isolated (99% yield) as a white foam: mixture of anomers _Rf (100% EtOAc) = 0.36; mp 74-80°C. ¹ H NMR (400MHz, CDCl ₃ )d 8.84(bs, 1H), 8.04(d, J=6.4Hz, 0.67H), 7.67-7.63(m, 4H), 7.51-7.39(m, 6.33H), 6.11 (d, J=20Hz, 0.33H), 5.98(d, J=16.4Hz, 0.67H), 5.88(bs, 1H), 5.41(d, J=52.4Hz, 0.33H), 5.23(dd, J= 50.4 and 4Hz, 0.67H), 4.56(m, 0.33H), 4.45(m, 0.67H), 4.23(dd, J=12.0 and 1.6Hz.0.67H), 3.89(dd, J=11.2 and 3.2Hz, 0.33H), 3.74-3.66(m, 1H), 2.45-1.96(m, 2H), 1.09(s, 6H), 1.06(s, 3H); ¹³ C NMR (100MHz, CDCl ₃ )d 158.6(d, J=14.4Hz), 158.4(d, J=14.4Hz), 153.9, 153.8, 136.6(d, J=240.5Hz), 136.3(d, J=239.7Hz), 135.6, 135.56, 135.5, 135.4, 133.1, 132.9, 132.5, 132.4, 130.1, 130.0, 129.9, 127.9, 127.8, 125.8(d, J=33.4Hz), 124.6(d, J=32.6Hz), 96.5(d, J=182.0Hz), 91.7(d, J=185.1), 90.7(d, J=35.6Hz), 87.7(d, J=15.2Hz), 81.5, 79.5, 64.9, 63.0, 33.5(d, J=20.5Hz), 30.6(d, J=20.4 Hz), 26.9, 26.8, 19.22, 19.18; IR (thin film) 3300, 2960, 1682, 1608, 1513, 1109cm ^-1 ; HRMS theoretical value [M+Li]C ₂₅ H ₂₉ N ₃ O ₃ SiF ₂ Li: 492.2106 The measured value: 492.2085. Theoretical value of elemental analysis. C ₂₅ H ₂₉ N ₃ O ₃ SiF ₂ ·1/2 H ₂ O: C, 60.71; H, 6.11; N, 8.50. The measured value: C, 60, 67; H, 6.03; N, 8.44.

Typical methods for deprotection of silyl-protected nucleosides: α- and β-(L)-2',3'-dideoxy-2'-fluoro-5-fluorocytidine (28a and 28b)

Nucleoside 25 (1.098 g, 2.26 mmol, 1.0 eq.) was dissolved in 15 mL of methanol, and ammonium fluoride (0.838 g, 22.6 mmol, 10.0 eq.) was added thereto. It was stirred vigorously for 24 hours after which TLC (15% ethanol/85% ethyl acetate) indicated the reaction was complete. The reaction mixture was diluted with 3 volumes of ethyl acetate and filtered through a small (1 cm) plug of silica gel. The plug was washed with 200 mL of a 15% ethanol/85% ethyl acetate solution, and the solvent was removed to give a white foam. This mixture was purified by column chromatography on silica gel, eluting with a 15% ethanol/85% ethyl acetate solvent system, which also separated the alpha and beta anomers. A white foam was obtained 0.190 g (0.768 mmol, 34% yield), while β 0.290 g (1.17 mmol, 52% yield) was obtained as a white foam: (28a) R _f (15% EtOH, 85% EtOAc) = 0.22 ;mp 199-203°C (decomposition). ¹ H NMR (400MHz, CD ₃ OD)d 7.78(d, J=6.8Hz, 1H), 6.07(d, J=19.2Hz, 1H), 5.37(d, J =54.0Hz, 1H), 4.60(m, 1H), 3.80(dd, J=12.0 and 3.2Hz, 1H), 3.56(dd, J=12.4 and 4.4Hz, 1H), 2.40-2.00(m, 21i) ; ¹³ C NMR (100MHZ, DMSO-d ₆ )d 157.7(d, J=13.6Hz), 153.2, 135.9(d, J=239.0Hz), 126.2(d, J=31.1Hz), 92.4(d, J =183.6Hz), 86.7(d, J=15.2Hz), 79.6, 62.7, 33.3(d, J=20.5Hz); IR(KBr) 3343, 3100, 1683, 1517, 1104cm ^-1 ; HRMS theoretical value [M +Li] C ₉ H ₁₁ N ₃ O ₃ F ₂ Li: 254.0929. Found value: 254.0919. Elemental analysis theoretical value, C ₉ H ₁₁ N ₃ O ₃ F ₂ 1/2 H ₂ O: C, 42.19; H , 4.72; N, 16.40. Found: C, 42.44; H, 4.56; N, 16.56. (28b) R _f (15% EtOH, 85% EtOAc) = 0.37; mp 182-186 °C (decomposition). ¹ H NMR (400MHz, DMSO-d ₆ )d 8.32(d, J=7.6Hz, 1H), 7.79(bs, 1H), 7.53(bs, 1H), 5.81(d, J=16.8Hz, 1H), 5.37( t, J=4.8Hz), 5.18(dd, J=51.6 and 3.2Hz, 1H), 4.32(m, 1H), 3.88(dd, J=12.0 and 2.8Hz, 1H), 3.59(dd, J=12.4 and 2.4Hz, 1H), 2.20-1.99(m, 2H); ¹³ C NMR (100MHz, DMSO-d ₆ )d 157.7(d, J=13.7Hz), 153.2, 136.1(d, J=237.4Hz), 125.3(d, J=33.4Hz), 97.3(d, J=176.8Hz), 89.9(d, J=35.7Hz), 81.6, 60.2, 30.3 (d, J=19.7Hz); IR(KBr) 3487, 2948, 1678, 1509, 1122cm ^-1 , HRMS theoretical value [M+Li]C ₉ H ₁₁ N ₃ O ₃ F ₂ Li: 254.0929. Found value: 254.0935. Elemental analysis theoretical value. _{C 9} H ₁₁ N ₃ O ₃ F ₂ : C, 43.73; H, 4.49; N, 17.00. Found value: C, 43.69; H, 4.53; N, 16.92.

(D)-5′-O-(tert-butyldiphenylsilyl)-2’,3’-dideoxy-2′-fluoro-5-fluorouridine (9)

Mixture of anomers _Rf (1:1 hexane/EtOAc) = 0.48; mp 65-70°C. ¹ H NMR (400MHz, CDCl ₃ )d 10.0 (bm, 1H), 7.99 (d, J = 5.6Hz, 0.63H), 7.65 (m, 4H), 7.42 (m, 6.37H), 6.12 (dd, J = 18.0 and 1.6Hz, 0.37H), 6.00 (d, J = 16Hz, 0.63H), 5.37 (dd, J = 54.6 and 2.4Hz, 0.37H), 5.22 (dd, J = 50.4 and 4Hz, 0.63H) , 4.57(m, 0.37H), 4.44(m, 0.63H), 4.22(dd, J=12.2 and 2.0Hz, 0.63H), 3.92(dd, J=11.2 and 3.2Hz, 0.37H), 3.70(m , 1H), 2.22(m, 2H), 1.09(s, 5.67H), 1.074(s, 3.33H); ¹³ C NMR (100MHz, CDCl ₃ )d 157.2(d, J=31.7Hz), 157.1(d , J=25.8Hz), 149.1, 148.8, 140.4 (d, J=236.6Hz), 140.1 (d, J=235.2Hz), 135.6, 135.5, 135.4, 132.9, 132.7, 132.4, 132.3, 130.1, 130.0, 129.9 , 127.9, 127.8, 125.1 (d, J=34.9 Hz), 123.6 (d, J=34.1 Hz), 96.4 (d, J=182.0 Hz), 92.0 (d, J=185.9 Hz), 90.2 (d, J = 37.2 Hz), 87.0 (d, J = 15.2 Hz), 81.7, 79.8, 64.8, 63.0, 33.3 (d, J = 21.2 Hz), 31.0 (d, J = 21.2 Hz), 26.9, 26.8, 19.2; IR (Film) 3185, 1722, 1117cm ^-1 ; HRMS theoretical value [M+1] C ₂₅ H ₂₉ N ₂ O ₄ SiF ₂ : 487.1866. Measured value: 487.1853. Elemental analysis theoretical value C ₂₅ H ₂₉ N ₂ O ₄ SiF ₂ : C, 61.71; H, 5.80; N, 5.76. Found: C, 61.72; H, 5.86; N, 5.72.

(D)-5'-O-(tert-butyldiphenylsilyl)-2',3'-dideoxy-2'-fluoro-5-fluorocytidine (10) 

Mixture of anomers _Rf (100% EtOAc) = 0.36; mp 75-81°C. ¹ H NMR (400MHz, CDCl ₃ )d 8.50(bm, 1H), 8.05(d, J=6.0Hz, 0.67H), 7.67-7.63(m, 4H), 7.51-7.39(m, 6.33H), 6.10 (d, J=20Hz, 0.33H), 5.98(d, J=16.4Hz, 0.67H), 5.62(bm, 1H), 5.41(d, J=52.4Hz, 0.33H), 5.23(dd, J= 51.6 and 4Hz, 0.67H), 4.57(m, 0.33H), 4.48(m, 0.67H), 4.24(dd, J=12.4 and 2.0Hz, 0.67H), 3.89(dd, J=11.2 and 3.2Hz, 0.33H), 3.74-3.66(m, 1H), 2.39-1.95(m, 2H), 1.09(s, 6H), 1.06(s, 3H); ¹³ C NMR (100MHz, CDCl ₃ )d 158.4(d, J=14.4Hz), 158.3(d, J=15.2Hz), 153.8, 153.7, 136.5(d, J=240.5Hz), 136.2(d, J=241.8Hz), 135.59, 135.56, 135.4, 133.0, 132.9, 132.5, 132.4, 130.1, 130.0, 129.9, 127.9, 127.8, 124.8(d, J=31.9Hz), 96.5(d, J=181.3Hz), 91.8(d, J=175.2Hz), 90.7(d, J=175.2Hz), 90.7(d, J= 24.9Hz), 87.8(d, J=21.2Hz), 81.6, 79.6, 64.9, 63.0, 33.5(d, J=19.7Hz), 30.6(d, J=21.3Hz), 26.9, 26.8, 19.2, 14.2; IR (thin film) 3304, 2959, 1680, 1621, 1508, 1105cm ^-1 ; HRMS theoretical value [M+Li] C ₂₅ H ₂₉ N ₃ O ₃ SiF ₂ Li: 492.2106. Measured value: 492.2110. Elemental analysis theoretical value. _{C25H29N3O3SiF2} : C, 61.84; H, 6.02; N _, 8.65. Found: C, _{61.86 ;} H, 6.09; N, 8.55 _.

(D)-N ⁴ -acetyl-5'-O-(tert-butyldiphenylsilyl)-2',3'-dideoxy-2'-fluoro-cytidine (11)

Mixture of anomers _Rf (15% EtOH, 85% EtOAc) = 0.75; mp 81-86°C. ¹ H NMR (400MHz, CDCl ₃ )d 10.58(bs, 1H), 8.40(d, J=7.2Hz, 0.61H), 7.86(d, J 7.6Hz, 0.38H), 7.67-7.65(m, 4H) , 7.51-7.41(m, 6H), 7.27(d, J=8.4Hz, 1H), 6.12(t, J 15.8Hz, 1H), 5.51(d, J=52.6Hz, 0.38H), 5.21(dd, J=50.8 and 2.9Hz, 0.61H), 4.62(m, 0.38H), 4.54(m, 0.61H), 4.28(d, J=11.5Hz, 0.61H), 3.95(dd, J=11.9 and 3.2Hz , 0.38H), 3.79-3.70(m, 1H), 2.46-2.04(m, 5H), 1.12(s, 5.49H), 1.07(s, 3.42H); ¹³ C NMR (100MHz, CDCl ₃ )d 171.5 , 171.3, 163.4, 154.9, 144.9, 144.1, 135.5, 135.4, 133.0, 132.8, 132.5, 132.2, 130.2, 130.1, 129.9, 128.0, 127.8, 96.8(d, J=91.1Hz), 96.2(d9, J=147. Hz), 92.3, 91.2 (d, J 35.7 Hz), 90.5, 88.5 (d, J = 15.9 Hz), 81.9, 80.1, 64.7, 62.9, 33.5 (d, J = 20.5 Hz), 30.5 (d, J = 20.5 Hz). 5 I4z), 26.9, 26.8, 24.9, 24.8, 19.3, 19.2; IR (thin film) 3237, 2932, 1722, 1671, 1559, 1493, 1107cm ^-1 ; HRMS theoretical value [M+Li]C ₂₇ H ₃₂ N ₃ O ₄ FSiLi: 516.2306. Measured value: 516.2310. Elemental analysis theoretical value. C ₂₇ H ₃₂ N ₃ O ₄ FSi: C, 63.63; H, 6.33; N, 8.24. Measured value: C, 63.45; H, 6.42; N , 8.09.

(D)-5′-O-(tert-butyldiphenylsilyl)-2′,3′-dideoxy-2′-fluoro-cytidine (12)

Mixture of anomers R _f (15% EtOH, 85% EtOAc) = 0.50; mp 98-104 °C. ¹ H NMR (360 MHz, CDCl ₃ ) d 7.97 (d, J = 7.2 Hz, 0.64 H, H -6), 7.65(m, 4H), 7.47-7.38(m, 6.36H), 6.15(d, J=20.5Hz, 0.36H), 6.05(d, J=16.6Hz, 0.64H), 5.83(d , J=7.9Hz, 0.36H), 5.46(d, J=7.2Hz, 0.64H), 5.30-5.10(m, 1H), 4.55(m, 0.36H), 4.44(m, 0.64H), 4.22( d, J=9.7Hz, 0.64H), 3.88-3.63(m, 1.36H), 2.38-1.95(m, 2H), 1.09(s, 5.76H), 1.06(s, 3.24H); ¹³ C NMR( 100MHz, CDCl ₃ )d 166.1, 155.8, 141.5, 140.5, 135.6, 135.4, 133.1, 132.9, 132.8, 132.4, 130.1, 130.0, 129.8, 128.0, 127.9, 127.8, 96.7 (d, J = 193.4Hz (), d, J = 140.3Hz), 94.5, 90.8 (d, J = 35.6Hz), 90.8, 87.8 (d, J = 15.9Hz), 81.2, 79.4, 65.0, 63.2, 33.7 (d, J = 21.2Hz), 3 0.8 (d,, J=20.4Hz), 26.9, 26.8, 19.3, 19.2: IR (thin film) 3470, 3339, 1644, 1487, 1113cm ^-1 ; HRMS theoretical value [M+Li]C ₂₅ H ₃₀ N ₃ O ₃ FSiLi: 474.2201. Found value: 474.2198. Elemental analysis theoretical value. C ₂₅ H ₃₀ N ₃ O ₃ FSi: C, 64.21; H, 6.47; N, 8.99. Found value: C, 64.04; H, 6.58; N , 8.76.

α-(D)-2',3'-dideoxy-2'-fluoro-5-fluorouridine (14a)

_Rf (100% EtOAc) = 0.38; mp 153-155°C. ¹ H NMR (360MHz, CD ₃ OD)d 7.80(d, J=6.8Hz, 1H), 6.11(d, J=18.7Hz, 1H), 5.35(d, J=52.9, 1H), 4.59(m, 1H), 3.81(d, J=11.9Hz, 1H), 3.57(dd, J=12.6 and 3.6Hz, 1H), 2.36-2.15(m, 2H); ¹³ C NMR (100MHz, CD ₃ OD)d 159.6 (d, J=25.8Hz), 150.7, 141.5(d, J=230.6Hz), 127.0(d, J=34.9Hz), 93.9(d, J=185.1Hz), 88.5(d, J=15.1Hz) , 81.8, 64.3, 34.3 (d, J=20.5Hz); IR(KBr) 3421, 3081, 1685, 1478, 1111cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₀ N ₂ O ₄ F ₂ Li : 255,0769, measured value: 255.0778. elemental analysis theoretical value C ₉ H ₁₀ N ₂ O ₄ F ₂ : C, 43.56; H, 4.06; N, 11.29. measured value: C, 43.59; H, 4.11; N, 11.17.

β-(D)-2',3'-dideoxy-2'-fluoro-5-fluorouridine (14b) 

_Rf (100% EtOAc) 0.54; mp 152-154°C. ¹ H NMR (360 MHz, CD ₃ OD) d 8.41 (d, J = 7.2 Hz, 1 H), 5.89 (d, J 16.6 Hz, 1 H), 5.21 (dd, J = 51.5 and 3.6 Hz, 1 H), 4.41 ( m, 1H), 4.00(d, J=12.6Hz, 1H), 3.67(d, J=12.2Hz, 1H), 2.25-2.09(m, 2H); ¹³ C NMR (100MHz, CD ₃ OD)d 159.7 (d, J=25.8Hz), 150.7, 141.8(d, J=229.8Hz), 126.3(d, J=36.4Hz), 98.3(d, J=179Hz), 91.9(d, J=37.1Hz), 83.6, 61.9, 31.9 (d, J=20.5Hz); IR(KBr) 3417, 3056, 1684, 1474, 1105cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₀ N ₂ O ₄ F ₂ Li: 255.0769. Found value: 255.0764. Elemental analysis theoretical value C ₉ H ₁₀ N ₂ O ₄ F ₂ : C, 43.56; H, 4.06; N, 11.29. Found value: C, 43.37; H, 3.98; N, 11.22.

α-(D)-2′,3′-dideoxy-2’-fluoro-5-fluorocytidine (15a)

_Rf (15% EtOH, 85% EtOAc) = 0.22; mp 198-202°C (dec.). ¹ H NMR (400MHz, CD ₃ OD)d 7.78(d, J=6.8Hz, 1H), 6.07(d, J=18.8Hz, 1H), 5.37(d, J=54.0Hz, 1H), 4.59(m , 1H), 3.80 (dd, J=12.0 and 3.2Hz, 1H), 3.57 (dd, J=12.4 and 4.4Hz, 1H), 2.38-2.14 (m, 2H); ¹³ C NMR (100MHz, CD ₃ OD )d 159.9 (d, J = 13.6Hz), 156.5, 138.3 (d, J = 240.4Hz), 127.5 (d, J = 33.4Hz), 93.6 (d, J = 184.3Hz), 89.5 (d, J = 15.9Hz), 81.8, 64.4, 34.5 (d, J=20.5Hz); IR(Y.Br) 3486, 3098, 1681, 1519, 1108cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₁ N ₃ O ₃ F ₂ Li: 254.0929. Measured value: 254.0929. Elemental analysis theoretical value C ₉ H ₁₁ N ₃ O ₃ F ₂ ·1/2 H ₂ O: C, 42.19; H, 4.72; N, 16.40. Measured value: C, 41.86; H, 4.75; N, 16.36.

β-(D)-2′,3′-dideoxy-2’-fluoro-5-fluorocytidine (15b)

_Rf (15% EtOH, 85% EtOAc) = 0.37; mp 181-183°C (decomposition). ¹ H NMR (400MHz, CD ₃ OD)d 8.45 (d, J=7.2Hz, 1H), 5.92 (dd, J=16.2 and 1.2Hz, 1H), 5.18 (dd, J=50.9 and 4.0Hz, 114) , 4.46(m, 1H), 4.05(dd, J=12.4 and 2.4Hz, 1H), 3.72(dd.J=12.8 and 2.4Hz, 1H), 2.27-2.05(m, 2H); ¹³ C NMR (100MHz , CD ₃ OD)d 159.9(d, J=13.6Hz), 156.5, 138.5(d, J=240.5Hz), 126.9(d, J=33.4Hz), 98.4(d, J=179.0Hz), 92.5( d, J=36.4Hz), 83.6, 61.9, 31.6 (d, J=20.5Hz); IR(KBR) 3494, 2944, 1689, 1522, 1106cm ^-1 ; HEMS theoretical value [M+Li]C ₉ H ₁₁ N ₃ O ₃ F ₂ Li: 254.0929. Measured value: 254.0936. Elemental analysis theoretical value. C ₉ H ₁₁ N ₃ O ₃ F ₂ : C, 43.73; H, 4.49; N, 17.00. Measured value: C, 43.84; H, 4.47; N, 17.05.

α-(D)-N ⁴ -acetyl-2',3'-dideoxy-2'-fluoro-cytidine (16a)

_Rf (15% EtOH, 85% EtOAc) = 0.40; mp 208-212°C. ¹ H NMR (360 MHz, DMSO-d ₆ )d (10.91, bs, 1H), 8.05 (d, J = 7.2Hz, 1H), 7.25 (d, J = 7.2Hz, 1H), 6.08 (dd, J =19.1 and 2.9Hz, 1H), 5.42(d, J=52.2Hz, 1H), 4.97(bs, 1H), 4.54(m, 1H), 3.63(d, J=13.0Hz, 1H), 3.47(d , J=13.3Hz, 1H), 2.35-2.15(m, 2H), 2.11(s, 3M; ¹³ C NMR (100MHz, DMSO-d ₆ )d 171.0, 162.6, 154.3, 145.7, 94.9, 92.0(d, J=183.6Hz), 87.5(d, J=15.9Hz), 80.2, 62.6, 33.3(d, J=19.7Hz), 24.4; IR(KBr) 3436, 3227, 1702, 1661, 1442, ^1102cm-1 ; HRMS theoretical value [M+Li]C ₁₁ H ₁₄ N ₃ O ₄ FLi: 278.1128. Measured value: 278.1136. Elemental analysis theoretical value C ₁₁ H ₁₄ N ₃ O ₄ F: C, 48.71; H, 5.20; N, 15.49 . Found: C, 48.73; H, 5.23; N, 15.52.

β-(D)-N ⁴ -acetyl-2',3'-dideoxy-2'-fluoro-cytidine (16b)

_Rf (15% EtOH, 85% EtOAc) = 0.50; mp 174-178°C. ¹ HNMR (360MHz, DMSO-d ₆ )d(10.90, bs, 1H), 8.46(d, J=7.2Hz, 1H), 7.18(d, J=7.2Hz, 1H), 5.90(d, J=16.9 Hz, 1H), 5.27(d, J=52.9Hz, 1H), 5.27(bs, 1H), 4.39(m, 1H), 3.88(d, J=13.0Hz, 1H), 3.61(d, J=13.0 Hz, 1H), 2.09(s, 3H), 2.20-1.85(m, 2H); ¹³ C NMR (100MHz, DMSO-d ₆ )d 171.0, 162.6, 154.4, 144.7, 97.0(d, J=177.5Hz) , 95.0, 90.7(d, J=36.6Hz), 82.2, 60.3, 30.3(d, J=19.7Hz), 24.3; IR(KBr) 3447, 3245, 1703, 1656, 1497, 1122cm ^-1 ; HRMS theoretical value [M+Li]C ₁₁ H ₁₄ N ₃ O ₄ FLi: 278.1128. Measured value: 278.1133. Elemental analysis theoretical value C ₁₁ H ₁₄ N ₃ O ₄ F: C, 48.71; H, 5.20; N, 15.49. Measured value : C, 48.65; H, 5.22; N, 15.46.

α-(D)-2′,3’-dideoxy-2′-fluoro-cytidine (17a)

_Rf (15% EtOH, 85% EtOAc) = 0.08; mp 234-237°C (decomposition). ¹ H NMR (400 MHz, DMSO-d ₆ )d 7.52 (d, J = 7.6 Hz, 1H), 7.21 (bm, 2H), 6.05 (dd, J = 20.4 and 3.2 Hz, 1 H), 5.73 (d, J =7.2Hz, 1H), 5.28(d, J=52.4Hz, 1H), 4.93(t, J=5.6Hz, 1H), 4.45(m, 1H), 3.58(m, 1H), 3.43(m, 1H ), 2.26-2.13 (m, 2H); ¹³ C NMR (100MHz, DMSO-d ₆ )d 165.8, 155.0, 141.6, 93.3, 92.2 (d, J=182.8Hz), 86.6 (d,

J=15.1Hz), 79.4, 62.8, 33.3 (d, J=19.7Hz); IR(KBr) 3366, 3199, 1659, 1399, 1122cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₂ N ₃ O ₃ FLi: 236.1023. Measured value: 236.1014. Elemental analysis theoretical value C ₉ H ₁₂ N ₃ O ₃ F: C, 47.16; H, 5.28; N, 18.33. Measured value: C, 47.40; H, 5.34; N, 18.51.

β-(D)-2′,3’-dideoxy-2′-fluoro-cytidine (17b)

Nucleoside 25 (0.160 g, 0.59 mmol) was dissolved in 10 mL of saturated ammonia in methanol. After stirring for 5 minutes, the reaction was complete. The methanolic ammonia solution was removed and the resulting white solid was placed under vacuum and heated gently in a 60°C water bath for 2 hours to remove the acetamide by-product by sublimation. The white solid was crystallized from 5% methanol/95% dichloromethane to give a white crystalline solid in quantitative yield. _Rf (15% EtOH, 85% EtOAc) = 0.18; mp 191-195°C (decomposition). ¹ H NMR (360MHz, CD ₃ OD)d 8.10(d, J=7.2Hz, 1H), 5.92(d, J=17.3Hz, 1H), 5.82(d, J=7.6Hz, 1H), 5.13(d , J=50.0Hz, 1H), 4.39(m, 1H), 3.97(d, J=12.2Hz, 1H), 3.68(dd, J=13.0 and 2.5Hz, 1H), 2.21-2.00(m, 2H) ; ¹³ C NMR (100MHz, CD ₃ OD)d 165.9, 155.0, 140.8, 97.3(d, J=176.8Hz), 93.6, 90.3(d, J=35.6Hz), 81.3, 60.7, 31.0(d, J= 20.5Hz); IR(KBr) 3397, 3112, 1680, 1400, 1178, 1070cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₂ N ₃ O ₃ FLi: 236.1024. Measured value: 236.1028. Elemental analysis theory Value. _C9H12N3O3F : C, 47.16; H, 5.28; N, 18.33. Found: _C , _{47.01 ;} H, 5.21; N, 18.29.

(L)-5′-O-(tert-butyldiphenylsilyl)-2′,3′-dideoxy-2′-fluoro-thymidine (23)

Mixture of anomers R _f (10% MeOH/90% dichloromethane) = 0.56; mp 61-65 °C. ¹ H NMR (360, MHz, CDCl ₃ ) d 9.48 (bs, 1 H), 7.67 ( m, 4H), 7.45-7.37(m, 7H), 6.15(dd, J=20.2 and 3.2Hz, 0.36H), 5.99(d, J=18.4Hz, 0.64H), 5.34(d, J=51.8Hz , 0.36H), 5.24(dd, J=52.2 and 4.3Hz, 0.64H), 4.59(m, 0.36H), 4.45(m, 0.64H), 4.17(dd, J=12.2 and 2.5Hz, 0.64H) , 3.91(dd, J=11.9 and 2.9Hz, 0.36H), 3.81(dd, J=11.5 and 2.9Hz, 0.64H), 3.68(dd, J=10.8 and 3.6Hz, 0.36H), 2.40-2.12( m, 2H), 1.94(s, 1.08H), 1.61(s, 1.92H), 1.10(s, 5.76H), 1.07(s, 3.24H); ¹³ C NMR (100MHz, CDCl ₃ )d 164.1, 164.0 , 150.4, 150.2, 136.4, 135.6, 135.5, 135.4, 135.3, 135.2, 133.0, 132.8, 132.6, 130.1, 130.0, 129.9, 127.94, 127.90, 127.8, 110.8, 109.8, 1.3 199 (d, J= (d, J=185.8Hz), 90.7(d, J=36.4Hz), 86.6(d, J=15.2Hz), 80.9, 79.4, 64.9, 63.6, 33.4(d, J=20.5Hz), 32.0(d , J=21.2Hz), 27.0, 26.8, 19.4, 19.2, 12.6, 12.2; IR (thin film) 3183, 3050, 1696, 1506, 1188cm ^-1 ; HRMS theoretical value [M+Li]C ₂₆ H ₃₁ N ₂ O ₃ SiF: 489.2197. Measured value: 489.2175. Elemental analysis theoretical value C ₂₆ H ₃₁ N ₂ O ₃ SiF: C, 64.71; H, 6.47; N, 5.80. Measured value: C, 64.88; H, 6.56; N, 5.76 .

(L)-5'-O-(tert-butyldiphenylsilyl)-2',3'-dideoxy-2'-fluoro-5-fluorouridine (24) 

Mixture of anomers _Rf (1:1 hexane/EtOAc) = 0.48; mp 65-71°C. ¹ H NMR (400MHz, CDCl ₃ )d 9.08(bs, 0.4H), 9.00(bs, 0.6H) 8.01(d, J=5.4Hz, 0.6H), 7.65(m, 4H), 7.42(m, 6.4 H), 6.10 (dd, J=20.2 and 1.4Hz, 0.4H), 6.00 (d, J=16.0Hz, 0.6H), 5.35 (dd, J=52.4 and 1.6Hz, 0.4H), (5.22, dd, J=51.2 and 4Hz, 0.6H), 4.57(m, 0.4H), 4.44(m, 0.6H), 4.22(dd, J=12.4 and 2.0Hz, 0.6H), 3.91(dd, J=11.2 and 2.9Hz, 0.4H), 3.70(m, 1H), 2.45-2.00(m, 2H), 1.09(s, 5.4H), 1.07(s, 3.6H); ¹³ C NMR (100MHz, CDCl ₃ )d 156.9(d, J=26.5Hz), 148.8, 148.6, 140.3(d, J=236.7Hz), 140.1(d, J=235.1Hz), 135.6, 135.5, 135.4, 132.9, 132.7, 132.4, 132.3, 130.2, 130.1, 129.9, 127.9, 127.8, 125.1(d, J=34.9Hz), 123.6(d, J=34.2Hz), 96.4(d, J=182.9Hz), 92.0(d, J=186.6Hz), 90.2( d, J=36.0Hz), 86.9(d, J=15.1Hz), 81.7, 79.8, 64.8, 63.0, 33.2(d, J=20.5Hz), 30.9(d, J=20.4Hz), 26.9, 26.8, 19.2; IR (thin film) 3191, 1719, 1113cm ^-1 ; HRMS theoretical value [M+Li]C ₂₆ H ₃₁ N ₂ O ₃ SiF Li: 493.1946. Measured value: 493.1952. Elemental analysis theoretical value C ₂₆ H ₃₁ N _{2 O3SiF} : C, 61.71; H, 5.80; N, 5.76. Found: C, 61.73; H, 5.83; N, 5.77.

α-(L)-2′,3’-dideoxy-2’-fluoro-thymidine (26a)

_Rf (100% EtOAc) = 0.25; mp 147-149°C. ¹ H NMR (360MHz, CD ₃ OD)d 7.45(s, 1H), 6.11(dd, J=19.4 and 2.9Hz, 1H), 5.30(d, J=53.6Hz, 1H), 4.58(m, 1H) , 3.79(dd, J=12.2 and 2.2Hz, 1H), 3.55(dd, J=2.2 and 3.6Hz, 1H), 2.40-2.15(m, 2H), 1.87(s, 3H); ¹³ C NMR (100MHz , CD ₃ OD) d 166.6, 152.3, 138.6, 110.5, 93.9 (d, J = 185.1 Hz), 88.3 (d, J = 15.1 Hz), 81.7, 64.4, 34.5 (d, J = 20.5 Hz), 12.6; IR(KBr) 3436, 3166, 1727, 1667, 1362, 1186c ^-1 ; HRMS theoretical value [M+Li] C 10 H ₁₃ N ₂ O ₄ FLi: 251.1019. _Measured value: 251.1014. Elemental analysis theoretical value C ₁₀ H ₁₃ N ₂ O ₄ F: C, 49.18; H, 5.37; N, 11.47. Found. C, 49.32; H, 5.40; N, 11.29.

β-(L)-2′,3′-dideoxy-2’-fluoro-thymidine (26b)

_Rf (100% EtOAc) = 0.38; mp 186-188°C. ¹ H NMR (360MHz, CD ₃ OD)d 7.94(s, 1H), 5.93(d, J=17.6Hz, 1H), 5.20(d, J=51.8Hz, 1H), 4.40(m, 1H), 3.98 (d, J=11.9Hz, (H), 3.68(d, J=13.0Hz, 1H), 2.37-2.10(m, 2H), 1.83(s, 3H); ¹³ C NMR (100MHz, CD ₃ OD) d 166.7, 152.3, 138.2, 111.0, 98.4 (d, J=178.3Hz), 92.1 (d, J=36.4Hz), 83.1, 62.4, 32.5 (d, J=20.5Hz), 12.6; IR(KBr) 3478 , 3052, 1684, 1363, 1192, 1005cm ^-1 ; elemental analysis theoretical value C ₁₀ H ₁₃ N ₂ O ₄ F: C, 49.18; H, 5.37; N, 11.47. Measured value: C, 49.29; H, 5.44; N, 11.36.

α-(L)-2′,3’-dideoxy-2’-fluoro-5-fluorouridine (27a)

_Rf (100% EtOAc) = 0.38; mp 155-157°C. ¹ H NMR (400MHz, CD ₃ OD)d 7.80(d, J=6.8Hz, 1H), 6.13(d, J=20.0Hz, 1H), 5.35(d, J=54.4Hz, 1H), 4.63(m .1H), 3.81 (dd, J=11.9 and 3.2Hz, 1H), 3.58 (dd, J=12.4 and 2.0Hz, 1H), 2.41-2.15(m, 2H); ¹³ C NMR (100MHz, CD ₃ OD )d 159.6 (d, J = 25.8Hz), 150.7, 141.5 (d, J = 230.6Hz), 127.0 (d, J = 34.9Hz), 93.9 (d, J = 184.3Hz), 88.5 (d, J = 15.1Hz), 81.9, 64.3, 34.3 (d, J=20.5Hz); IR(KBr) 3401, 3098, 1661, 1458, 1018cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₀ N ₂ O ₄ F ₂ Li: 255.0769. Found value: 255.0771. Elemental analysis theoretical value C ₉ H ₁₀ N ₂ O ₄ F ₂ : C, 43.56; H, 4.06, N, 11.29. Found value: C, 43.70; H, 4.17; N , 11.15.

β-(L)-2',3'-dideoxy-2'-fluoro-5-fluorouridine (27b) 

_Rf (100% EtOAc) = 0.54; mp 153-156°C. ¹ H NMR (400MHz, CD ₃ OD) d 8.46 (d, J=6.8Hz, 1H), 5.94 (d, J=16.4Hz, 1H), 5.25 (dd, J=51.6 and 4.0Hz, 1H), 4.41 (m, 1H), 4.05 (dd, J=12.8 and 2.4 Hz, 1H), 3.72 (dd, J=12.4 and 2.4 Hz, 1H), 2.34-2.09 (m, 2H); ¹³ C NMR (100 MHz, CD ₃ OD)d 159.7(d, J=25.8Hz), 150.7, 141.8(d, J=230.6Hz), 126.3(d, J=35.7Hz), 98.3(d, J=184.6Hz), 91.9(d, J=36.4Hz), 83.6, 61.9, 31.9 (d, J=20.5Hz); IR(KBr) 3482, 3037, 1702, 1654, 1402, 1103cm ^-1 ; HRMS theoretical value [M+Li]C ₉ H ₁₀ N ₂ O ₄ F ₂ Li: 255.0769. Found value: 255.0764. Elemental analysis theoretical value C ₉ H ₁₀ N ₂ O ₄ F ₂ : C, 43.56; H, 4.06; N, 11.29. Found value: C, 43.59; H , 4.06; N, 11.17.

Preparation of L-2'-fluoro-2',3'-unsaturated nucleosides

A second facile synthesis of unsaturated 2'-fluoronucleosides has now been accomplished and described below. This synthesis involves reacting a protected pyrimidine or purine base with key intermediate 309 in the presence of a Lewis acid, generally as described in Scheme 9 below. Typical compounds synthesized according to this synthesis method are shown in Table 5-6. the

Option 9

Reagents; (i) 2-methoxypropene, DMF, p-TsOH (ii) NalO ₄ , H ₂ O (iii)(EtO) ₃ P(O)CHFCO ₂ Et.NaHMDS, THF, -78°C (iv ) C-HCl.EtOH (v) TBDMSCl, imidazole, CH ₂ Cl ₂ (vi) DIBAL-H, CH ₂ Cl ₂ , -78°C (vii) Ac ₂ O, pyridine, CH ₂ Cl ₂ ,

Option 9

Reagents: (i) silylated uracil, TMSOT1, DCE (ii) silylated thymine, TMSOT1, DCE (111) silylated ^N4 -Bz-cytosine, TMSOTI, _CH3CN (iv )5-F-cytosine, TMSOTI, CH ₃ CN(v)TBAF, CH ₃ CN(vi)NH ₃ /MeOH

Option 9

Reagents: (i) silylated 6-Cl, purine, TMSOTI, DCE (ii) silylated s-Cl-2-F-purine, TMSOTI, DCE (iii) TBAF, _CH3CN (iv) NH ₃ /DME (v) NH ₃ /MeOH, 90 °C (vi) HSCH ₂ CH ₃ OH, MeOMe, MeOH, reflux,

table 5

As previously described, the synthesis of 2',3'-unsaturated-D-nucleosides has been accomplished by elimination reactions starting from readily available nucleoside analogs, involving lengthy modification reactions of individual nucleotides. Some have reported the preparation of D-2'-fluoro-2', 3'-unsaturated pyrimidine nucleosides by elimination of appropriate 2'-fluoronucleoside analogues (Martin, J.A. et al., J.Med Chem.1990 , 33, 2137-2145; Stezycki, R.Z. et al., J. Med. Chem. 1990, 33, 2150-2157). However, when using this method to synthesize L-Fd4N, some other difficulties were encountered in the preparation of the starting material L-nucleoside. Since the 2,3-unsaturated sugar moiety is unstable in the presence of Lewis acids under coupling conditions, there are very few examples of synthesis of 2′,3′-unsaturated purine nucleosides by direct condensation, with only one pyrimidine analog In some cases, a thiophenol-based intermediate is used (Abdel-Medied, A.W.S. et al., Synthesis 1991, 313-317; Sujino, K. et al., Tetrahedron Lett. 1996, 37, 6133-6136). In contrast to 2,3-unsaturated sugar moieties, 2-fluoro-2,3-unsaturated sugars have increased stability of the glycosyl linkage upon condensation with heterocycles and are expected to become more stable for direct coupling reactions. Therefore, (R)-2-fluorobutenolide 506 was selected as the precursor of the key intermediate 508, which can be prepared from L-glyceraldehyde acetonide (glyceraldehyde acetonide) 501. the

Starting from L-glyceraldehyde acetonide, (E)- 502/(Z)-2 mixture ( ^1H NMR detection 9:1) (Thenappan, A. et al., J.Org.Chem., 1990, 55, 4639-4642; Morikawa, T. et al., Chem.Pharm. Bull. 1992, 40, 3189-3193; Patrick, TB et al., J. Org. Chem. 1994, 59, 1210-1212). Due to the difficulty in separating the (E)-502/(Z)-502 isomers, this mixture was used in the following cyclization reaction under acidic conditions to give the desired lactone 503 and the uncycled di Alcohol 504. The resulting mixture was converted to the silylated lactone 506, which was reduced with DIBAL-H in dichloromethane at -78°C to give lactol 507. Treatment of this lactol 507 with acetic anhydride gave key intermediate 508, which was condensed with silylated 6-chloropurine under Vorburggen conditions to give anomer mixture 509. Treatment of 509 with TBAF in THF gave free nucleosides 510 and 511, which were readily separated by silica gel chromatography. Compounds 510 and 511 were treated with mercaptoethanol and NaOMe in stainless steel vials at 90°C to afford adenine analogs 512 and 513, respectively. Treatment of compounds 510 and 511 with mercaptoethanol and NaOMe gave inosine analogs 514 and 515, respectively. The stereochemistry of these compounds was determined from NOESP spectra (cross-peak between H-1' and H-4' in B isomer 512).

Scheme 10. Synthesis of L-2'-fluoro-d4 adenine and hypoxanthine by direct condensation

Reagents: (i) (EtO) ₂ P(O)CHFCO ₂ Et, [(CH ₃ ) ₃ Si] ₂ NNa, THF, -78°C (ii) HCVEtOH (iii) TBDMSCl, imidazole, CH ₂ Cl ₂ (iv ) 1 M DIBAL-H in CH ₂ Cl ₂ , CH ₂ Cl ₂ , -78°C (v) Ac ₂ O, pyr., CH ₂ Cl ₂ (vi) silylation of 6-Cl-purine, TMSOTl, DCE (vii) TBAF, CH ₃ CN (viii) NH ₃ /MgOH, 90°C (ix) HS(CH ₂ ) ₂ OH, NaOMe/MeOH, reflux

Table 7. Half effective value (EC ₅₀ ) and half inhibitory value (IC ₅₀ ) of L-2'-fluoro-d4 adenine and hypoxanthine against HIV-1 in PBM

Experimental part

Melting points were detected with a Mel-temp II experimental setup and were not calibrated. NMR spectra were recorded on a Bruker 250 and AMX400 400 MHz chromatograph using tetramethylsilane as an internal standard; chemical shifts (δ) are reported in parts per million (ppm), while signals are described as s (singlet), d (doublet), t (triplet), q (quartet), br s (broad singlet), dd (doublet doublet) and m (multiplet). UV spectra were obtained from a Beckman DU 650 spectrometer. Optical activity was measured on a Jasco DIP-370 digital polarimeter. Mass spectra were detected on a Micromass Inc. Autospec high-resolution double-focus sector-shaped (EBE) MS spectrometer. Infrared spectra were recorded on a Nicolet 510 FT-IR spectrometer. Elemental analysis was performed by Atlantic Microlab, Inc., Norcross, GA. All reactions were monitored with thin layer chromatography Analtech, 200 mm silica gel GF plates. Distilled with _Ca2H to obtain dry 1,2-dichloroethane, dichloromethane and acetonitrile before use. Distillation with sodium and benzophenone gave dry THF when the solution turned purple.

L-(S)-Glyceraldehyde acetonide (302) 

A solution of L-gulonic acid-γ-lactone (175 g, 0.98 mol) in DMF (1 L) was cooled to 0° C. and p-toluenesulfonic acid (1.1 g, 5.65 mmol) was added portionwise with stirring. To the resulting solution, 2-methoxypropene (87.7 g, 0.92 mol) was added dropwise through a dropping funnel at 0°C. The reaction mixture was warmed to room temperature and stirred for an additional 24 hours. After the reaction was complete, sodium carbonate (124 g) was added and the resulting suspension stirred vigorously for 3 hours. Then, filter through a glass filter and evaporate the filtrate in vacuo to give a yellow residue, which crystallizes upon addition of toluene (170 mL). The solid was filtered with suction, washed with hexane/ethanol (9:1; 1 L), and dried to give 301 as a pale yellow solid (99.1 g, 65%). the

To a stirred suspension of 5,6-O-isopropylidene-L-gulonic acid-1,4-lactone (70.0 g, 0.32 mol) in water (270 mL) at 0° C. Sodium metaperiodate (123 g, 0.58 mol) was added in portions over 30 minutes, maintaining pH 5.5 (adjusted by addition of 2N sodium hydroxide). The suspension was stirred at room temperature for 2 hours, then saturated with sodium chloride and filtered. The pH of this filtrate was adjusted to 6.5-7.0, and extracted with dichloromethane (5 times, 200 mL) and ethyl acetate (5 times, 300 mL). The combined organic layers were dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure (<20°C). The resulting residue was then distilled to give 302 (23.2 g, 69%) as a colorless oil. bp49-51°C/16Torr. [α] _D 25-66.4 (c 6.3, benzene).

(E)/(Z)-ethyl-3-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-fluoroacrylate (E- 303 and Z-303)

A solution of triethyl 2-fluorophosphorylacetate (39.2 g, 162 mmol) in THF (70 mL) was cooled to -78 °C, and sodium bis(trimethylsilyl)amide (1.0 M in THF, 162 mL) was added dropwise , 162 mmol). This mixture was maintained at -78 °C for 30 min, then a solution of 303 (19.14 g, 147 mmol) in THF (70 mL) was added. After stirring at -78°C for 1 hour, the reaction mixture was treated with aqueous ammonium chloride and extracted with ether. The ether phase was washed with saturated sodium chloride, dried over magnesium sulfate, filtered and evaporated. Chromatography of this residue on silica gel afforded E-303 and Z-303 (9:1 by ¹ H NMR) as pale yellow oil (34.6 g, 97.9%). ¹ HNMR (CDCl ₃ ) 81.34, 1.36 (2t, J=8Hz, -CH ₂ CH ₃ ), 1.40, 1.45 (2s, -CH ₃ ), 3.69 (m, H _a -5), 4.28 (m, H _b -5, _{-CH2CH3 )} , 5.02(m, H-4), 5.40(m, H-4), 6.02(dd, J=8, 20Hz, H-3), 6.18(dd, J=8 , 32Hz, H-3).

(R)-(+)-4-[(tert-butyldimethylsilyloxy)methyl]-2-fluoro-2-butene-4-lactone (307) 

A solution of E-303 and Z-303 (19.62 g, 89.89 mmol) in 110 mL of absolute ethanol was treated with 30 mL of concentrated hydrochloric acid and stirred at room temperature for 2 hours. The solvent was removed in vacuo and the residue was co-evaporated with toluene (3 x 300 mL) to give lactone 304 and uncycled ester 305. The obtained light yellow syrup was directly used in the next reaction without purification. To a mixture of 304, 305 and imidazole (12.3 g, 180 mmol) in dichloromethane (250 mL) was added tert-butyldimethylsilyl chloride (27.1 g, 180 mmol) and the reaction mixture was stirred at room temperature 4 hours. The resulting mixture was washed with water, dried over magnesium sulfate, filtered and concentrated to dryness. The residue was separated by silica gel column chromatography using 4% EtOAc-hexanes as eluent to afford 307 (28.0 g, 70.2% from compound 302) as a white crystalline solid. mp48-50°C; [α] _D +105.3 (c1.60, CHCl ₃ ); ¹ H NMR (CDCl ₃ ) δ0.07, 0.08 (2s, 2xCH ₃ ), 0.88 (s, tert-butyl), 3.88 ( m, 2H, H-5), 5.01 (m, 1H, H4), 6.73 (ps t, 1H, J=4Hz); elemental analysis theoretical value C ₁₀ H ₁₉ FO ₃ Si: C, 53.63; H, 7.77. Found: C, 53.70; H, 7.75.

1-Acetyl-4-[(tert-butyldimethylsilyloxy)methyl]-2-fluoro-2-butene-4-lactone (309)

Under nitrogen atmosphere, lactone 307 (20.59 g, 83.54 mmol) was dissolved in 200 mL of dichloromethane, then cooled to -78 °C, and a 1.0 M solution of DIBAL-H in dichloromethane (125 mL) was added. The resulting compound was stirred at -78°C for 2 hours. The cold mixture was treated with dilute nitric acid and dried (sodium sulfate). The solvent was evaporated to give the anomer 308 as a light yellow oil (16.6 g, 80% crude yield), which was directly used in the next reaction without purification. the

_Ac2O (25 mL, 0.27 mol) was added to a solution of 308 and pyridine (22 mL, 0.27 mol) in dichloromethane (200 mL) at 0 °C, and the resulting mixture was stirred for 16 hours. The reaction mixture was washed with dilute hydrochloric acid, saturated sodium bicarbonate and brine. The combined organic layers were dried, filtered and concentrated to dryness. The residue was purified by column chromatography (6.5% ethyl acetate/hexanes) to afford 309 (12.6 g, 65%) as a colorless oil.

A General Method for the Condensation of Acetate 309 and Pyrimidine Base

Under a nitrogen atmosphere, a mixture of uracil (420 mg, 3.75 mmol), hexamethyldisilazane (15 mL) and ammonium sulfate (20 mg) was refluxed for 3 hours. The resulting clear solution was concentrated to dryness in vacuo. To a solution of sugar 309 (728 mg, 2.50 mmol) and silylated base in dry DCE (20 ml) was added TMSOTf (0.7 mL, 3.14 mmol) at 0°C. The reaction mixture was stirred under nitrogen atmosphere for 2 hours, poured into cold saturated sodium bicarbonate solution (30 mL) and stirred for 15 minutes. The resulting mixture was washed, dried (sodium sulfate), filtered and concentrated in vacuo. The crude product was purified by column chromatography (3% methanol/chloroform) to give 310 (0.960 g, 2.73 mmol, 73%) as an inseparable anomer, which was directly used in the next reaction without isolation. the

1-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-L-glyceryl-pent-2-enylfuranosyl]uracil (310) 

UV(CHCl ₃ )λ _max 257.5nm.; elemental analysis (C ₁₅ H ₂₃ N ₂ O ₄ Si) C, H, N.

1-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-L-glyceryl-pent-2-enylfuranosyl]thymine (311)

Silylated thymidine (242mg, 1.92mmol), 307 (500mg, 1.72mmol) and TMSOTf (0.5mL, 2.25mmol) were reacted for 2 hours to give a mixture of 311, which was subjected to silica gel column chromatography (3% methanol/chloroform ) was purified to an inseparable mixture of anomers (0.392 g, 1.10 mmol, 64%). UV (CHCl ₃ ) λ max 262.0 nm. Elemental Analysis (C ₁₆ H ₂₅ FN ₂ O ₄ Si) C, H, N.

N ⁶ -benzoyl-1-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-(a,b)-L-glyceryl-pentyl- 2-enfuranosyl]cytosine (312 and 313)

Silylated ^N6 -benzoylcytosine (790 mg, 3.67 mmol), 307 (470 mg, 1.62 mmol) and TMSOTf (0.5 mL, 2.25 mmol) were reacted for 2 h to give a mixture of 312 and 313 which was passed through silica gel Column (30% ethyl acetate/hexanes) purification afforded the β anomer 312 (0.34 g, 0.76 mmol, 47.1%) as a white solid, and the α anomer 313 (0.23 g, 0.52 mmol, 31.8%) as a white solid. 312: UV (CHCl ₃ ) λ max 260.5nm; elemental analysis (C ₂₂ H ₂₈ FN ₃ O ₄ Si) C, H, N.; 513: UV (CHCl ₃ ) λ _max 260.5nm.; elemental analysis (C ₂₂ H ₂₈ FN ₃ O ₄ Si) C, H, N.

5-fluoro-1-[5-O-(tert-butyldimethylsilyll-2,3-dideoxy-2-fluoro-(a,b-L-glyceryl-pent-2-enefuranosyl ] Cytosine (314 and 315)

Silylated 5-fluoro-cytosine (300mg, 2.32mmol), 309 (360mg, 1.24mmol) and TMSOTf (0.4mL, 1.86mmol) were reacted for 2 hours to give a mixture of 314 and 315, which was subjected to silica gel column chromatography Purification (3% MeOH/dichloromethane) afforded the beta anomer 314 (168 mg, 37.8%) and the alpha anomer 315 (121 mg, 27.1%) as white solids. 314: UV(MeOH) λ _max 281.5nm; 315: UV(MeOH)) λ _max 281.5mn.

1-(2,3-dideoxy-2-fluoro-(α,β)-L-glyceryl-pent-2-enylfuranosyl)uracil (316 and 317)

Tetra-n-butylammonium fluoride (0.6 mL, 0.6 mmol) was added to a mixture of 310 (177 mg, 0.52 mmol) in THF (15 mL) and the reaction mixture was stirred at room temperature for 15 minutes. The solvent was removed and the residue was purified by silica gel column chromatography (2% MeOH/CHCl ₃ ) to give β anomer 316 (52.8 mg, 0.23 mmol, 44.5%) and α anomer 317 (35.1 mg, 0.15 mmol, 29.6%).

316: UV (H ₂ O) λ _max 261.0mn (pH7); elemental analysis (C ₉ H ₉ FN ₂ O ₄ ·0.3H ₂ O) C, H, N. 317: UV(H ₂ O)λ _max 261.0nm (pH7); elemental analysis (C ₉ H ₉ FN ₂ O ₄ ·0.2H ₂ O) C, H, N.

1-(2,3-dideoxy-2-fluoro-(α,β)-L-glyceryl-pent-2-enfuryl)thymine (318 and 319)

Tetra-n-butylammonium fluoride (0.8 mL, 0.8 mmol) was added to a mixture of 311 (240 mg, 0.67 mmol) in THF (10 mL) at 0 °C, and the reaction mixture was stirred at room temperature for 15 min. The solvent was removed and the residue was purified by silica gel column chromatography (40% THF/cyclohexane) to give β anomer 318 (66.5 mg, 0.28 mmol, 41%) and α anomer 319 (52.8 mg , 0.23nunol, 26%). the

318: UV(H ₂ O)λ _max 265.5nm (pH7); elemental analysis (C ₉ H ₉ FN ₂ O ₄ ·0.3H ₂ O) C, H, N. 319: UV(H ₂ O)λ _max 266.0nm (pH7); elemental analysis (C ₉ H ₉ FN ₂ O ₄ ·0.3H ₂ O) C, H, N.

N ⁶ -benzoyl-1-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)cytosine (320)

Tetra-n-butylammonium fluoride (1M in THF) (1 mL, 1 mmol) was added to a solution of β anomer 312 (280 mg, 0.63 mmol) in THF (10 mL) and the reaction was stirred at room temperature for 1 Hour. The reaction mixture was concentrated under reduced pressure and the residue was purified by flash silica gel column eluting with 2.5% MeOH/ _CHCl3 to afford 320 (218 mg, 0.66 mmol, 75%) as a white solid.

UV(MeOH) λ _max 260.5nm. Elemental Analysis (C ₁₆ H ₁₄ FN ₃ O ₄ ) C, H, N.

N ⁶ -benzoyl-1-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)cytosine (321)

Tetra-n-butylammonium fluoride (1M in THF) (1 mL, 1 mmol) was added to a solution of the alpha anomer 313 (280 mg, 0.63 mmol) in THF (10 mL) and the reaction was stirred at room temperature for 1 Hour. The reaction mixture was concentrated under reduced pressure and the residue was purified by flash silica gel column eluting with 2.5% MeOH/ _CHCl3 to afford 321 (145.8 mg, 0.44 mmol, 69%) as a white solid.

UV(MeOH) λ _max 260.5nm. Elemental Analysis (C ₁₆ H ₁₄ FN ₃ O ₄ ·0.3H ₂ O) C, H, N.

1-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)cytosine (322) 

A solution of the β anomer (67.60 mg, 0.204 mmol) in methanol (5 mL) was treated with _NH3 /MeOH (10 mL sat. solution) and the reaction mixture was stirred at room temperature until disappearance of the starting material was observed (10 h ). The reaction mixture was concentrated under reduced pressure and the residue was purified by preparative TLC using 12% MeOH/dichloromethane as eluent. Material 322 (43 mg, 93.1%) was obtained from this plate as a solid which was triturated with hexane and ether.

UV (H ₂ O) λ _max 266.5nm (pH7); elemental analysis (C ₉ H ₁₀ FN ₃ O ₃ .0.4H ₂ O) C, H, N.

1-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)cytosine (323) 

A solution of the alpha anomer (65.90 mg, 0.199 mmol) in methanol (5 mL) was treated with _NH3 /MeOH (10 mL sat. solution) and the reaction mixture was stirred at room temperature until disappearance of the starting material was observed (16 h ). The reaction mixture was concentrated under reduced pressure and the residue was purified by preparative TLC using 12% MeOH/dichloromethane as eluent. Material 323 (42.5 mg, 94.5%) was obtained from this plate as a solid which was triturated with hexane and ether.

UV (H ₂ O) λ _max 276.0nm (pH7); elemental analysis (C ₉ H ₁₀ FN ₃ O ₃ ) C, H, N.

5-Fluoro-1-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)cytosine (324)

Tetra-n-butylammonium fluoride (1M in THF) was added to a solution of the beta anomer 314 in acetonitrile and the reaction was stirred at room temperature for 1 hour. The reaction mixture was concentrated under reduced pressure and the residue was purified by flash silica gel column eluting with 12% MeOH/ _CHCl3 to afford 324.

5-Fluoro-1-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)cytosine (325) 

Tetra-n-butylammonium fluoride (1M in THF) was added to a solution of the alpha anomer 315 in acetonitrile and the reaction was stirred at room temperature for 1 hour. The reaction mixture was concentrated under reduced pressure and the residue was purified by flash silica gel column eluting with 12% MeOH/ _CHCl3 to give 325.

General method for the condensation of acetate 309 with purine bases

Under a nitrogen atmosphere, a mixture of 6-chloropurine (1.20 g, 7.75 mmol), hexamethyldisilazane (25 mL) and ammonium sulfate (catalytic amount) was refluxed for 4 hours. The resulting clear solution was concentrated to dryness in vacuo and the residue was dissolved in anhydrous DCE (10 mL) and mixed with a solution of 307 (1.50 g, 5.17 mmol) in DCE (40 mL) and trimethyl triflate at room temperature The silyl ester (1.5 mL, 7.75 mmol) was reacted. After stirring at room temperature under a nitrogen atmosphere for 1 hour, the reaction solution was poured into ice-cold saturated sodium bicarbonate solution (20 mL) and stirred for 15 minutes. The organic layer was washed with water and brine, and dried over magnesium sulfate. The solvent was removed under reduced pressure and the residue was separated by silica gel column chromatography with 12.5% ethyl acetate/hexanes to afford anomer mixture 326 (1.25 g, 62.9%) as a syrup. the

6-Chloro-9-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-L-glyceryl-pent-2-enefuranosyl]purine ( 326)

326: UV(MeOH) λ _max 265.0nm; elemental analysis (C ₁₆ H ₂₂ ClFN ₄ O ₂ Si) C, H, N.

6-Chloro-2-fluoro-9-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-(α,β)-L-glyceryl-pentyl -2-enfuranosyl]purine (327 and 328)

A mixture of silylated 2-fluoro-6-chloropurine [prepared from 1.170 g (6.78 mmol) of 2-fluoro-6-chloropurine] and anhydrous DCE (40 mL) was stirred at room temperature for 16 hours. After work-up similar to 326, purification by silica gel column chromatography (12% ethyl acetate/hexanes) afforded the β anomer 327 (685 mg, 1.70 mmol, 30.0%) as a white foam and the α anomer 328 ( 502mg, 1.25nunol, 22.1%) pale yellow syrup. the

327: UV(MeOH) λ _max 268.5 nm. Elemental Analysis (C ₁₆ H ₂₁ F ₂ ClN ₄ O ₂ Si) C, H, N., 328: UV(MeOH) λ _max 269.0 nm. Elemental Analysis (C ₁₆ H ₂₁ F ₂ ClN ₄ O ₂ Si) C, H, N.

6-Chloro-9-(2,3-dideoxy-2-fluoro-(α,β)-L-glyceryl-pent-2-enylfuranosyl)purine (329 and 330)

A solution of 326 (1.2 g, 3.12 mmol) in anhydrous _CH3CN (20 mL) was treated with TBAF (1 M in THF) (3.2 ml, 3.2 mmol) and stirred for 1 h. After evaporation of the solvent, the residue was purified by column chromatography (3% methanol/chloroform) to give β anomer 329 (296 mg, 35%) as a white solid and α anomer 330 (380 mg, 45%) as a foam.

329: UV(MeOH) λ _max 265.0 nm.; 330: UV (MeOH) λ _max 265.0 nm.

6-Amino-2-fluoro-9-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-ene Furanosyl] purine (331) and

6-Chloro-2-amino-9-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-ene Furanosyl]purine (332)

Dry ammonia gas was bubbled into a stirred solution of 327 (420 mg, 1.04 mmol) in anhydrous DME (35 mL) at room temperature overnight. Salts were removed by filtration and the filtrate was evaporated under reduced pressure. This residue was purified by silica gel column chromatography (25% EtOAc/Hexane) to afford two compounds, 331 (114 mg, 0.30 mmol) and 332 (164 mg, 0.41 mmol) as white solid. the

331: UV(MeOH) λ _max 268, 5nm. Elemental analysis (C ₁₆ H ₂₃ F ₂ N ₅ O ₂ Si·0.2 acetone) C, H, N; 332: UV(MeOH) λ _max 307.5 nm. Elemental Analysis (C ₁₆ H ₂₃ FN ₅ O ₂ ClSi) C, H, N, CL.

6-Amino-2-fluoro-9-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-ene Furanosyl]purine (333) and 6-chloro-2-amino-9-[5-O-(tert-butyldimethylsilyl)-2,3-dideoxy-2-fluoro-α-L -Glyceryl-pent-2-enefuranosyl]purine (334)

Dry ammonia gas was bubbled into a stirred solution of 333 (420 mg, 1.04 mmol) in dry DME (35 mL) at room temperature overnight. Salts were removed by filtration and the filtrate was evaporated under reduced pressure. This residue was purified by silica gel column chromatography (25% EtOAc/Hexane) to afford two compounds, 332 (150 mg, 0.30 mmol) and 333 (150 mg, 0.38 mmol) as white solid. the

333: UV(MeOH) λ _max 269.0 nm. Elemental analysis (C ₁₆ H ₂₃ F ₂ N ₅ O ₂ Si·0.3 acetone) C, H, N; 332: UV(MeOH) λ _max 309.5 nm. Elemental Analysis (C ₁₆ H ₂₃ FClN ₅ O ₂ Si) C, H, N.

9-(2,3-dideoxy-2-fluoro-β-glyceryl-pent-2-enylfuranosyl)adenine (335) 

329 (100 mg, 0.369 mmol) and saturated _NH3 /MeOH (50 mL) were heated in a stainless steel bottle at 90 °C for 24 h. After cooling to room temperature, the solvent was removed under reduced pressure and the residual syrup was purified by column chromatography with 6% MeOH/ _CHCl3 as eluent to afford 335 (70 mg, 75%) as a white solid. 335: UV (H ₂ O) λ _max 258nm (ε18,800) (pH2), 258.5nm (ε18,800) (pH7), 258.5nm (ε19,100) (pH11). Elemental Analysis (C ₁₀ H ₁₀ FN ₅ O ₂ .0.2H ₂ O) C, H, N.

9-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)adenine (336)

330 (100 mg, 0.369 mmol) and saturated _NH3 /MeOH (50 mL) were heated in a stainless steel bottle at 90 °C for 24 h. After cooling to room temperature, the solvent was removed under reduced pressure and the residual syrup was purified by column chromatography with 6% MeOH/ _CHCl3 as eluent to afford 335 (72 mg, 78%) as a white solid. 336: UV (H ₂ O) λ _max 258nm (ε21, 100) (pH2), 259nm (ε21, 500) (pH7), 29nm (ε22, 600) (pH11). Elemental Analysis (C ₁₀ H ₁₀ FN ₅ O ₂ .0.3 MeOH) C, H, N.

9-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)hypoxanthine (337)

A mixture of 329 (100 mg, 0.369 mmol), NaOMe (0.5M in methanol) (2.94 mL, 1.46 mmol) and _HSCH2CH2OH (0.1 mL, 1.46 mmol) in methanol (20 _mL ) was refluxed for 4 Hour. The reaction mixture was cooled, neutralized with glacial acetic acid and evaporated to dryness in vacuo. The residue was purified by silica gel column chromatography (10% methanol/chloroform) to give 337 (74 mg, 80%) as a white solid. 337: UV (H ₂ O) λ _max 247nm (ε12,400) (pH2), 247.5nm (ε13,000) (pH7), 253nm (ε13,100) (pH11). Elemental Analysis (C ₁₀ H ₉ FN ₄ O ₃ .0.2H ₂ O) C, H, N.

9-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)hypoxanthine (338)

A mixture _of 330 (100 mg, 0.369 mmol), NaOMe (0.5M in methanol) (2.94 mL, 1.46 mmol) and _HSCH2CH2OH (0.1 mL, 1.46 mmol) in methanol (20 mL) was refluxed for 4 Hour. The reaction mixture was cooled, neutralized with glacial acetic acid and evaporated to dryness in vacuo. The residue was purified by silica gel column chromatography (10% methanol/chloroform) to give 338 (70 mg, 80%) as a white solid. 338: UV (H ₂ O) λ _max 247.5nm (ε12, 700) (pH2), 247.5nm (ε13, 700) (pH7), 252.5nm (ε13, 100) (pH11). Elemental Analysis (C ₁₀ H ₉ FN ₄ O ₃ .0.3H ₂ O) C, H, N.

2-fluoro-6-amino-9-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)purine (339) 

A solution of 31 (101 mg, 0.26 mmol) in anhydrous acetonitrile (15 mL) was treated with TBAF (1 MT in THF) (0.35 mL, 0.35 mmol) and stirred for 30 minutes. After solvent evaporation, the residue was purified by column chromatography (9% dichloromethane/methanol) to give 339 (64.7 mg, 0.24 mmol, 92.3%) as a white crystalline solid. UV (H ₂ O) λ _max 269.0nm (pH7).

2-Fluoro-6-amino-9-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)purine (340)

A solution of 333 (73.4 mg, 0.19 mmol) in anhydrous acetonitrile (10 mL) was treated with TBAF (1 M in THF) (0.25 mL, 0.25 mmol) and stirred for 30 minutes. After solvent evaporation, the residue was purified by column chromatography (9% dichloromethane/methanol) to give 340 (46.2 mg, 0.17 mmol, 90.3%) as a white crystalline solid. UV (H ₂ O) λ _max 269.0nm (pH7).

2-Amino-6-chloro-9-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)purine (341) 

A solution of 332 (143.5 mg, 0.40 mmol) in dry acetonitrile (15 mL) was treated with TBAF (1 M in THF) (0.60 mL, 0.60 mmol) and stirred for 30 minutes. After solvent evaporation, the residue was purified by column chromatography (5% dichloromethane/methanol) to give 341 (109 mg, 0.382 mmol, 90.3%) as a white crystalline solid. UV (H ₂ O) λ _max 308.5nm (pH7).

2-Amino-6-chloro-9-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)purine (342) 

A solution of 334 (145 mg, 0.36 mmol) in anhydrous acetonitrile (10 mL) was treated with TBAF (1 MT in THF) (0.50 mL, 0.50 mmol) and stirred for 30 minutes. After solvent evaporation, the residue was purified by column chromatography (9% dichloromethane/methanol) to give 342 (99.9 mg, 0.35 mmol, 96.4%) as a white crystalline solid. UV (H ₂ O) λ _max 309.0nm (pH7).

9-(2,3-dideoxy-2-fluoro-β-L-glyceryl-pent-2-enylfuranosyl)guanine (343)

341 (63.6 mg, 0.223 mmol), 2-mercaptoethanol (0.06 mL, 0.89 mmol) and 1N NaOMe (0.89 mL, 0.89 mmol) in methanol (10 mL) were refluxed for 5 hours under nitrogen atmosphere. The mixture was cooled, neutralized with glacial acetic acid and concentrated to dryness under reduced pressure. The residue was purified by column chromatography (12% dichloromethane/methanol) to give 343 (30.1 mg, 0.113 mmol, 50.7%) as a white solid. UV (H ₂ O) λ _max 253.5nm (pH7).

9-(2,3-dideoxy-2-fluoro-α-L-glyceryl-pent-2-enylfuranosyl)guanine (344)

342 (59.3 mg, 0.208 mmol), 2-mercaptoethanol (0.07 mL, 1.04 mmol) and 1N NaOMe (1.04 mL, 1.04 mmol) in methanol (10 mL) were refluxed for 5 hours under nitrogen atmosphere. The mixture was cooled, neutralized with glacial acetic acid and concentrated to dryness under reduced pressure. The residue was purified by column chromatography (12.5% dichloromethane/methanol) to give 344 (28.0 mg, 0.105 mmol, 50.5%) as a white solid. UV (H ₂ O) λ _max 253.0nm (pH7).

Synthesis of cis-(±)-carbocyclic d4 cytosine nucleoside and its 5'-triphosphate

Referring to Scheme 11, starting from diethyl diallylmalonate (701), 4-ethoxycarbonyl-1,6-heptadiene (702) was synthesized in 78% yield (WANugent, J.Am. Chem. Soc., 1995, 117, 8992-8998). Compound 703 was synthesized from compound 702 with a yield of 71% (LE Martinez, J.Org.Chem., 1996, 61, 7963-7966) and compound 705 was synthesized from compound 704 with a yield of 43% (DM Hodgson, J.Chem. Soc. Perkin Trans. 1, 1994, 3373-3378). The key intermediate cis-(±)-3-acetoxy-5-(acetoxymethyl)cyclopentene (708) can alternatively be synthesized from cyclopentadiene and formaldehyde in acetic acid using the Prins reaction (EASaville-Stones , J.Chem.Soc.PerkinTrans.1, 1991,2603-2604), although it has the problem of low yield and inseparability; or it can be synthesized by bicyclic lactone, which is synthesized by 4 steps through multiple steps (F. Burlina, Bioorg. Med. Chem. Lett., 1997, 7, 247-250). While requiring the synthesis of a chiral bicyclic lactone, the latter approach affords the chiral 708 [(-)-enantiomer]. Synthesis of N4-acetyl- ^{5-fluorocytosine from 5} -fluorocytosine and p-nitrophenyl acetate (ASSteinfeld, J. Chem. Research (M), 1979, 1437-1450).

Scheme 11

Experimental part

General: All reagents were used as received unless otherwise stated. Anhydrous reagents were purchased from Aldrich Chemical Co. Melting points (Mp) were determined with an electrothermal digital melting point apparatus without calibration. ¹ H and ¹³ C NMR spectra were monitored on a Varian Unity Plus 400 spectrometer at room temperature and reported in ppm downfield of the internal standard tetramethylsilane.

4-Ethoxycarbonyl-1,6-heptadiene (702)

A mixture of diethyl diallylmalonate (701; 50 g, 208 mmol), sodium cyanide (20.7 g, 422 mmol) and DMSO (166 mL) was heated at 160 °C for 6 hours. After cooling to room temperature, this mixture was added to 400 mL of water and the product was extracted with hexane (4 x 100 mL). After evaporation of the solvent under reduced pressure, the residue was distilled (42-43 °C/1 Torr) to afford 27.34 g (78%) of 702 as a colorless liquid. ¹ H NMR (400MHz, CDCl ₃ ) 65.80-5.70 (m, 2H, 2CH=CH ₂ ), 5.10-5.02 (m, 4H, 2CH=CH ₂ ), 4.14 (q, 2H, J=7.2Hz, OCH ₂ ), 2.54-2.48 (m, 1H, CH), 2.41-2.34, 2.29-2.23 (2m, 4H, 2CH ₂ ), 1.25 (t, J=7.2Hz, 3H, CH ₃ ).

(±)-Ethyl 3-cyclopentenecarboxylate (703) 

To a flame-dried 500 mL flask was added 2,6-dibromophenol (1.20 g, 4.76 mmol), tungsten oxychloride (0.813 g, 2.38 mmol) and anhydrous toluene (25 mL). The resulting suspension was heated to reflux for 1 hour under a nitrogen atmosphere, then the solvent was evaporated in vacuo. The solid residue was broken up with a spatula and dried under vacuum for 30 minutes. To this residue were added toluene (160 mL), _Et4Pb (1.54 g, 4.76 mL) and 702 (22 g, 131.0 mmol). Under a nitrogen atmosphere, the mixture was heated at 90°C for 1.5 hours. After cooling to room temperature, the mixture was filtered through celite, and the celite was washed with tert-butyl methyl ether. The combined filtrates were washed with 1% sodium hydroxide solution, water and brine and concentrated by evaporation under reduced pressure. The residue was distilled (37-38 °C/1 Torr) to give 13.06 g (71%) of 703 as a colorless liquid. ¹ H NMR (400MHz, CDCl ₃ ) δ5.67 (s, 2H, CH=CH), 4.14 (q, 2H, J=7.2Hz, OCH ₂ ), 3.11 (five small peaks, J=7.6Hz, 1H, CH), 2.65 (d, J=7.6Hz, 4H, 2CH2), 1.27 (t, J=7.2Hz, 3H, _CH3 ).

(±)-1-(Hydroxymethyl)-3-cyclopentene (704) 

To a cold (-78 °C) solution of 703 (7 g, 50 mmol) in anhydrous THF (150 mL), _LiAlH4 (1M in THF, 25 mL, 25 mmol) was added, and the reaction solution was heated at -78 °C under an argon atmosphere. Stirring was continued for 4 hours. The reaction solution was then allowed to warm to 0° C., and 2.5 mL of water, 2.5 mL of 15% sodium hydroxide and 7.5 mL of water were sequentially added. After warming to room temperature, the precipitate was filtered off through celite and the celite was washed with hot ethyl acetate. The combined filtrates were washed with 0.1 N NaOH and brine, dried (MgSO4), filtered, concentrated and dried in vacuo to afford 4.294 g (84%) of 704 as a light yellow liquid. ¹ H NMR (400MHz, CDCl ₃ ) δ5.68 (s, 2H, 2CH=CH),

3.57 (d, J = 6.0 Hz, 2H, _CH2OH ), 2.54-2.48 (m, 3H, CH+ _CH2 ), 2.15-2.10 (m, 2H, _CH2 ).

cis-(+)-4-(hydroxymethyl)-1,2-epoxycyclopentane (705) 

To a solution of 704 (930 mg, 9.1 mmol) and vanadyl acetylacetone (10 mg) in anhydrous dichloromethane (20 mL) was added dropwise tert-butyl formic acid [3M solution in dichloromethane, prepared from tert-butyl formic acid (70 % by weight in water, 41 mL, 0.3 mol) and dichloromethane (59 mL) were prepared by drying (2×MgSO ₄ ) and storing over 4 Angstrom molecular sieves, 10 mL, ca. 30 mmol]. After stirring at room temperature for 24 hrs, aqueous sodium sulfite solution (15% solution, 60 mL) was added, and the mixture was stirred at room temperature for 6 hrs. The organic layer was separated, washed with saturated sodium bicarbonate and brine, and concentrated. The residue was purified by flash chromatography on silica gel eluting with hexanes/ethyl acetate (2:1) to afford 460 mg (43%) of 705 as a colorless liquid. ¹ H NMR (400MHz, CDCl ₃ ) δ 3.54 (s, 2H, (CH) ₂ O), 3.49 (t, J=4.0Hz, 2H, CH ₂ OH), 2.95 (bs, 1H, OH), 2.44 -2.40 (m, 1H, CH), 2.05-2.02 (m, 4H, _2CH2 ). ¹³ C NMR (100 MHz, CDCl ₃ ) δ 66.9 (d, (CH) ₂ O), 59.2 (t, CH ₂ OH), 36.5 (d, CH), 31.4 (t, 2 CH ₂ ).

cis-(±)-3-acetoxy-5-(acetoxymethyl)cyclopentene (708) 

To a solution of diphenyl diselenide (2.70 g, 8.65 mmol) in absolute ethanol (100 mL) was added sodium borohydride in portions. This solution was stirred until the yellow color became colorless, then a solution of 705 (1.70 g, 14.4 mmol) in anhydrous THF (10 mL) was added. The reaction solution was heated to reflux under nitrogen for 1 hour, then the solvent was evaporated in vacuo. To this residue were added ethyl acetate (80 mL) and water (30 mL). The organic layer was separated, washed with brine, dried (magnesium sulfate), filtered, concentrated and dried in vacuo. The obtained (±)-1-hydroxy-4-(hydroxymethyl)-2-(phenylselenyl)-cyclopentane (706; pale yellow oil) was directly used in the next reaction without purification. To crude 706 was added anhydrous dichloromethane (60 mL), triethylamine (30 mL, 216 mmol) and DMAP (50 mg). The resulting solution was cooled to 0°C, and acetic anhydride (14.7 g, 144 mmol) was added dropwise. After stirring overnight at room temperature under an atmosphere of argon, the solvent was evaporated to give (±)-1-Acetoxy-4-(acetoxymethyl)-2-(phenylselenyl)-cyclopentane (707; pale yellow oil). To a solution of 707 in cold (0° C.) dichloromethane (50 mL) containing 3 drops of pyridine was added 30% hydrogen peroxide solution (20 mL) over 5 minutes. After stirring at 0°C for 30 minutes and at room temperature for 30 minutes, dichloromethane (50 mL) was added to dilute the reaction mixture. The organic phase was separated, washed with water, saturated sodium bicarbonate and brine, dried (magnesium sulfate), filtered and concentrated by evaporation in vacuo. This residue was purified by flash chromatography on silica gel eluting with 0-10% ethyl acetate in hexanes to afford 2.254 g (79% over 3 steps) of 708 as a light brown liquid. ¹ H NMR (400MHz, CDCl ₃ ) δ6.01-6.00, 5.92-5.90 (2m, 2H, CH=CH), 5.66-5.64 (m, 1H, H-3), 4.04 (d, J=6.8Hz, 2H, CH ₂ O), 2.98-2.92 (m, 1H, H-5), 2.53-2.46 (m, 1H, H-4a), 2.08, 2.04 (2s, 6H, 2CH ₃ ), 1.60-1.54 (m , 2H, H-4b). ¹³ C NMR (100MHz, CDCl ₃ ) δ171.1, 170.9(2s, 2C=O), 137.0, 131.4(2d, CH=CH), 79.2(d, C-3), 67.4(t, CH ₂ O) , 43.7 (d, C-5), 33.4 (t, C-4), 21.3, 20.9 (2q, 2CH ₃ ).

cis-(±)-carbocyclo-5'-O-acetyl-2',3'-didehydro-2',3'-dideoxy-5-fluorocytidine (709) 

A suspension of 5-fluorocytosine (258 mg, 2 mmol) and NaH (58 mg, 2.4 mmol) in anhydrous DMSO (15 mL) was heated at 70 °C for 30 min in a preheated oil bath. Then, the resulting solution was cooled to room temperature, and solutions of Pd(PPh ₃ ) ₄ (73 mg, 0.063 mmol) and 708 (298 mg, 1.5 mmol) in anhydrous THF (2 mL) were added, respectively. The reaction mixture was stirred at 70°C under argon atmosphere for 3 days. After removing the solvent by evaporation in vacuo, the residue was treated with dichloromethane (50 mL). The precipitate was filtered off through celite and the celite was washed with dichloromethane. The combined filtrates were concentrated and the residue was purified by flash chromatography on silica gel eluting with 0-5% methanol in dichloromethane to afford 40 mg (10%) of 709 as a light brown solid. Recrystallization from methanol/dichloromethane/hexanes gave pure product as a white powder. Mp182-184°C. ¹ H NMR (400MHz, CDCl ₃ ) δ7.43 (d, J=6.0Hz, 1H, H-6), 6.18-6.16 (m, 1H, H-3'), 5.83-5.81 (m, 1H, H -2'), 5.73-5.71(m, 1H, H-1'), 4.23-4.21, 4.08-4.04(2m, 2H, CH ₂ O), 3.14-3.12(m, 1H, H-4'), 2.92-2.84 (m, 1H, .H-6'a), 2.08 (s, 3H, _CH3 ), 1.41-1.35 (m, 1H, H-6'b).

cis-(±)-carbocyclo-N ⁴ , 5'-O-diacetyl-2',3'-didehydro-2',3'-dideoxy-5-fluorocytidine (710)

The title compound 710 was prepared from 708 (560 mg, 2.828 mmol) and ^N4 -acetyl-5-fluorocytosine (726 mg, 4.24 mmol) in a similar manner to 709: 560 mg (64%, brown oil). The crude product was directly used in the next reaction without purification.

cis-(±)-carbocyclo-N ⁴ , 5'-O-diacetyl-2',3'-didehydro-2',3'-dideoxycytidine (711)

The title compound 711 was prepared from 708 (272 mg, 1.37 mmol) and ^N4 -acetylcytosine (316 mg, 2.06 mmol) in a similar manner to 709: 108 mg (27%) of a white powder. Mp169.5-171.5°C. ¹ H NMR (400MHz, CDCl ₃ ) δ8.80(bs, 1H, NH), 7.72(d, J=6.8Hz, 1H, H-6), 7.39(d, J=6.8Hz, 1H, H-5 ), 6.19-6.17(m, 1H.H-3'), 5.86-5.81(m, 1H, H-2'), 5.77-5.75(m, 1H, H-1'), 4.17-4.13, 4.07- 4.02(2m, 2H, CH ₂ O), 3.18-3, 10(m, 1H, H-4'), 2.96-2.88(m, 1H.H-6'a), 2.27, 2.06(2s, 6H, 2 CH ₃ ), 1.43-1.37 (m, 1H, H-6'b). ¹³ C NMR (100MHz, CDCl ₃ ) δ170.8(s, 2C=O), 162.0(s, C-4), 155.6(s, C-2), 145.3(d, C-6), 139.2(d , C-3'), 130.0(d, C-2'), 96.8(d, C-5), 66.3(t, C-5'), 62.8(d, C-1'), 44.2(d, C-4'), 34.7 (t, C-6'), 25.0, 20.9 (2q, 2 CH ₃ ).

cis-(±)-carbocyclo-2',3'-didehydro-2',3'-dideoxy-5-fluorocytidine (712) 

To a flask containing 709 (33 mg, 0.12 mmol) was added NaOMe (0.5 M in methanol, 0.5 mL). The reaction solution was stirred at room temperature for 1 hour, and the solvent was evaporated in vacuo. The residue was purified by flash chromatography on silica gel eluting with 5-10% methanol in dichloromethane to afford 17 mg (61%) of 712 as a light brown solid. Recrystallization from methanol/dichloromethane/hexanes gave pure product as a white powder. Mp205.5-206.0℃. ¹ HNMR (400MHz, DMSO-d ₆ ) δ7.66 (d, J=6.0Hz, 1H, H-6), 7.60, 7.40 (2bs, 2H, NH ₂ ), 6.06-6.05 (m, 1H, H-3'), 5.68-5.65(m, 1H, H-2'), 5.53-5.50(m, 1H, H-1'), 4.77-4.75(m, 1H, H4') , 3.50-3.48, 3.41-3.37 (2m, 2H, H-5'), 2.79-2.77 (m, 1H, H-6'a), 1.34-1.27 (m, 1H, H-6'b). ¹³ C NMR (100MHz, DMSO-d ₆ ) δ157.0(d, J _CF =11.9Hz, C-4), 154.0(3, C-2), 139.2(d, C-3'), 135.8(d , J _CF =241.3Hz, C-5), 130.2(d, C-2'), 126.8(d, J _CF =11.8Hz, C-6), 63.5(t, C-51), 61.3(d, C-1'), 47.2 (d, C-4), 33.3 (t, C-6'). MS (FAB) m/e 226 (MH ⁺ ). Elemental analysis (C ₁₀ H ₁₂ FN ₃ O ₂ ) theoretical value C 53.33, H 5.37, N 18.66; found value C 53.10, H 5.40, N 18.44. Compound 712: 320 mg (59%, white powder) was also prepared from 710 (750 mg, 2.42 mmol) similarly to the above method.

cis-(±)-carbocyclo-2',3'-didehydro-2',3'-dideoxycytidine (713) 

The title compound 713 was prepared from compound 711 (75 mg, 0257 mmol) in a similar manner to the preparation of 712: 48 mg (90%, white solid). Mp200-201°C. ¹ H NMR (400MHz, DMSO-d ₆ ) δ7.40 (d, J=7.2Hz, 1H, H-6), 7, 03, 6.95 (2bs, 2H, NH ₂ ), 6.07-6.05 (m, 1H , H-3'), 5.67 (d, J=7.2Hz, 1H, H5), 5.65-5.64 (m, 1H, H-2'), 5.55-5.52 (m, 1H, H-l'), 4.71 -4.68(m, 1H, H4'), 3.43-3.36(m, 2H, H-5'), 2.78-2.76(m, 1H, H-6'a), 1.24-1.18(m, 1H, H- 6'b). ¹³ C NMR (100MHz, DMSO-d ₆ ) δ165.5(s, C-4), 155.8(s, C-2), 142.2(d, C-6), 138.6(d, C -3'), 130.5 (d, C-2'), 93.7 (d, C5), 63.9 (t, C-5'), 60.8 (d, C-1'), 47.3 (d, C-4' ), 34.0 (t, C-6'). MS (FAB) m/e 208 (MH ⁺ ). Elemental analysis (C ₁₀ H ₁₃ N ₃ O ₂ ) theoretical value D 57.96, H 6.32, N 20.28; found value C 57.35, H 6.27, N 20.02. HRMS (FAB) calcd (C ₁₀ H ₁₄ N ₃ O ₂ ): 208.1086; found 208.1088.

cis-(±)-carbocyclo-2',3'-didehydro-2',3'-dideoxy-5-fluorocytidine 5'-triphosphate, triethylhydrogen ammonium salt (714) 

To a solution of 712 (10 mg) in dry DMF (0.3 mL) and pyridine (0.1 ml) was added 2-chloro-4H-1,3,2-benzodioxin-4-one in 1 M dry 1, 4-Dioxane (0.05 mL) solution. The reaction was stirred at room temperature for 15 minutes. Then, a solution of pyrophosphoric acid-Bu ₃ N in 1M anhydrous DMF (0.12 mL) and Bu ₃ N (0.05 mL) were added sequentially. After stirring at room temperature for another 15 minutes, a solution of I ₂ /H ₂ O/pyridine/THF was added dropwise to the above solution until the color of iodine did not fade (ca. 0.5 mL), and then the mixture was concentrated by evaporation in vacuo. This residue was dissolved in water (2 mL), washed with dichloromethane (3 x 1 mL), filtered, and purified by FPLC (column: HiLoad 26/10 Q Sepharose Fast Flow; buffer A: 0.01M _{Et3NHCO 3} ; buffer B: 0.7 M Et ₃ NHCO ₃ ; flow rate: 10 mL/min; gradient: increase B from 0% at start to 10% at 4 min, increasing to 100% at 64 min). The appropriate fractions were collected and lyophilized to afford 714 as a colorless syrup. HPLC [column: 100×4.6mm Rainin HydroporeSAX ion exchange; buffer A: 10mM NH ₄ H ₂ PO ₄ in 10% methanol/H ₂ O (pH 5.5); buffer B: 125mM NH ₄ H ₂ PO ₄ in in 10% MeOH/H ₂ O (pH 5.5); flow rate: 1.0 mL/min; gradient: increase B from 0% at the beginning to 100% at 25 min], residence time: 11.9 min. MS (FAB) m/e 464 ([MH] ⁺ ).

cis-(±)-carbocyclo-2′,3′-didehydro-2′,3’-dideoxycytidine 5′-phosphate (715) 

The title compound 715 was prepared from 713 in a manner analogous to the preparation of 714. HPLC (conditions as above) retention time: 12.1 minutes. MS (FAB) m/e 446 ([MH] ⁺ ).

Inhibitory effect of (±)-carboxy-D4FC-triphosphate on HIV-1 reverse transcriptase

_12-18，5mMDTT，100μg/ml牛血清白蛋白和1μM ³H-dCTP(2Ci/mmol)。将3TCTP(0.001-50μM)作为阳性对照。将化合物在37℃下在反应混和物中与1单位HIV-1 RT孵育一小时。加入等体积的冷10％TCA/0.05％焦磷酸钠停止该反应并在4℃下孵育30分钟。用Packard手动收获仪(Meriden.CT) 将沉淀的核酸收集在玻璃纤维过滤纸上。用Packard 9600 Direct Beta计数器测定放射标记吸收的每分钟计数(cpm)。  r(I) _n ·(dC) _12-18 homopolymer template primer (Pharmacia, Piscataway, NJ) and HIV-1 heterodimer p66/51 reverse transcriptase (RT, Biotechnology General, Rehoval, Israel) were used. The standard reaction mixture (100 μl) contains 100 mM Tris-Hcl (pH8.0), 50 mM KCl, 2 mM MgCl ₂ , 0.05 units/ml r(I) _n ·

_12-18 , 5 mMDTT, 100 μg/ml bovine serum albumin and 1 μM ³ H-dCTP (2 Ci/mmol). 3TCTP (0.001-50 μM) was used as a positive control. Compounds were incubated in the reaction mixture with 1 unit of HIV-1 RT for one hour at 37°C. The reaction was stopped by adding an equal volume of cold 10% TCA/0.05% sodium pyrophosphate and incubated at 4°C for 30 minutes. Precipitated nucleic acids were collected on glass fiber filter paper with a Packard manual harvester (Meriden.CT). Radiolabel uptake was measured in counts per minute (cpm) using a Packard 9600 Direct Beta counter.

IV. Anti-HIV activity

In one embodiment, the disclosed compounds or pharmaceutically acceptable derivatives or salts thereof or medicaments containing these compounds are used for the prevention and treatment of HIV infection and related diseases, such as AIDS-related syndrome (ARC), persistent generalized lymphoid disease, HIV-positive and HIV-positive conditions, Kaposi's sarcoma, thrombocytopenic purpura, and opportunistic infections. In addition, these compounds or formulations may be used prophylactically to prevent or delay progression of clinical disease in individuals who are anti-HIV antibody or HIV antigen positive or have been exposed to HIV. the

The ability of nucleosides to inhibit HIV can be tested by a variety of experimental techniques. One of the techniques detailed below is the detection of inhibition of viral replication in human peripheral blood mononuclear (PBM) cells infected with HIV-1 (strain LAV) stimulated with phytohemagglutinin (PHA). The amount of virus produced was determined by detection of virus-encoded reverse transcriptase. The amount of enzyme produced is proportional to the amount of virus produced. the

Antiviral and Cytotoxic Assays:

The anti-HIV-1 activity of these compounds was determined in human peripheral blood mononuclear (PBM) cells as previously described (Schinazi, RF; McMillan, A.; Cannon, D.; Mathis, R.; Lloyd, RMJr.; Peck , A.; Sonimadossi, J.-P.; St. Clair, M.; Wilson, J.; Furman, PA; Painter, G.; Choi, W.-B.; 36, 2423; Schinazi, RF; Sommadossi, J.-P.; Saalmann, V.; Cannon, D.; Xie, M.-Y.; Hart, G.; Smith, G.; Hahn, E. Antimicrob. Agents Chemother. 1990, 34, 1061). Stock solutions (20-40 mM) of these compounds were prepared in sterile DMSO and then diluted to the desired concentration in complete medium. A stock solution of 3'-azido-3'-deoxythymidine (AZT) was prepared in water. Cells were infected with prototype HIV-1 _LA1 at a multiplicity of 0.01. The virus obtained from the cell supernatant was quantified on day 6 after infection by a reverse transcriptase assay using poly(rA) _n · oligo(dT) _12-18 as a template primer. The presence of DMSO in dilute solutions (<0.1%) should have no effect on virus yield. Toxicity of these compounds can be assessed in human PBM, CEM and Vero cells. Antiviral _EC50 and cytotoxic _IC50 were obtained from concentration-effect curves using the half effective method described by Chou and Talalay (Adv. Enzyme Regul. 1984, 22, 27).

Phytohemagglutinin-stimulated PBM cells (10 ⁶ cells/ml) obtained from healthy donors with hepatitis B and HIV-1 seronegativeness and survived for three days were treated with HIV-1 (strain LAY) at a concentration of about 100 times 50% tissue culture infectious dose (TICD 50 ) per milliliter was infected and cultured in the presence or absence of different concentrations of antiviral compounds.

Approximately 1 hour after infection, medium containing test compound (concentration twice the final concentration in medium) or compound-free was added to the flask (5 ml; final volume 10 ml). AZT was used as a positive control. the

Cells were exposed to virus (approximately 2×10 ⁵ dpm/ml, detected by reverse transcriptase assay) and placed back in the carbon dioxide incubator. HI-1 (strain LAV) was obtained from Center for Disease Control, Atlanta, Georgia. Methods for culturing PBM cells, harvesting virus, and assaying reverse transcriptase activity are described in McDougal et al. (J. Immun. Meth. 76, 171-183, 1985) and Spira et al. 99, 1987), except that amphotericin B was not included in the medium (see Schinazi et al., Antimicrob. Agents Chemother, 32, 1784-1787 (1988); Id., 34: 1061-1067 (1990)).

On day 6, cells and supernatant were transferred to 15 ml tubes and centrifuged at approximately 900 g for 10 minutes. 5 ml of the supernatant was removed and the virus was concentrated by centrifugation (Beckman 70.1 Ti centrifuge) at 40000 rpm for 30 minutes. Dissolved viral pellets were processed to measure the concentration of reverse transcriptase. Results are expressed in dpm/ml of sample supernatant. Smaller amounts of virus obtained from the supernatant (1 ml) were also concentrated by centrifugation before lysis and assayed for reverse transcriptase concentration. the

The half effective (EC ₅₀ ) concentration was determined by the half effective method (Antimicrob. Agents Chemother, 30, 491-498 (1986). Briefly, the percent inhibition of the virus was expressed by micromolar of the compound as determined from the detection of reverse transcriptase. Concentrations are plotted. _EC50 is the concentration of compound at which virus growth is inhibited by 50%.

Under conditions similar to those of the antiviral experiments described above, uninfected human PBM cells (3.8×10 ⁵ cells/ml) stimulated with mitogens can be cultured in the presence or absence of drugs. After 6 days the cells were counted with a hemocytometer and by trypan blue exclusion as described by Schinazi et al., Antimicrobial Agents and Chemotherapy, 22(3), 499 (1982). _IC50 is the concentration of compound at which normal cell growth is inhibited by 50%.

Table 7 provides anti-HIV activity data for selected compounds. With this experiment, the EC ₅₀ of (±)-carbocycle-D4FC-TP (2', 3'-unsaturated-5-fluorocytidine was determined to be 0.40 μM, while (±)-carbocycle-D4C-TP( 2',3'-unsaturated cytidine) has an EC ₅₀ of 0.38 μM.

V. Anti-hepatitis B activity

The ability of active compounds to inhibit the growth of hepatitis virus in 2.2.15 cell cultures (HepG2 cells transformed with hepatitis virus particles) can be evaluated according to the method detailed below. the

A general and detailed description of the detection of antiviral effects and the analysis of HBV DNA in this culture system has been published (Korba and Milman, 1991, Antiviral Res, 15:217). Antiviral evaluation experiments are best performed on two separate phases of cells. All wells in the assay plate were seeded at the same density at the same time. the

Due to genetic variation of intracellular and extracellular HBV DNA, inhibition is considered only if greater than 3.5-fold (for HBV virion DNA) or 3.0-fold (for HBV DNA replication intermediates) the average level of HBV DNA forms in untreated cells It was statistically significant (P<0.05). The concentration of integrated HBV DNA in each cellular DNA preparation (which was a constant per cell in these experiments) was used to calculate the concentration of the intracellular HBV DNA form to ensure equal amounts of cellular DNA between isolated samples. the

Typical values for extracellular HBV virion DNA in untreated cells are 50 to 150 pg/ml culture medium (average about 76 pg/ml). In untreated cells, intracellular HBV DNA replication intermediates ranged from 50 to 100 μg/pg cellular DNA (average about 74 pg/μg cellular DNA). In summary, the inhibition of intracellular HBV virion DNA concentration, as a result of treatment with antiviral compounds, was insignificant and occurred very slowly (Korba and Milman, 1991, Antiviral Res., 15:217). the

Hybridization assays can be performed in these experiments to yield the equivalent of approximately 1.0 pg of intracellular HBV DNA to 2-3 chromosomal copies per cell and 1.0 pg/ml of intracellular HBV DNA to 3 x ¹⁰⁵ viral particles/ml.

Toxicity assays were performed to assess whether any observed antiviral effects were due to gross effects on cell viability. The method used here is to detect the uptake of a neutral red dye (standard and widely used to detect cell viability substances in a variety of viral host systems including HSV and HIV). Toxicity assays were performed in 96-well flat bottom culture plates. Cells for toxicity assays were incubated and treated with test compounds using the same protocol as for antiviral evaluation as described below. Four concentrations of each compound were tested and each concentration was performed in triplicate cultures (wells A, B and C). The level of toxicity was determined by the absorption of neutral red dye. The absorbance of the intrinsic dye at 510 nm (A _sin ) was used for quantitative analysis. Values are expressed as mean _Asin values from 9 independent cultures as a percentage of untreated cells maintained on the same 96-well plate as the test compound.

VI. Anti-hepatitis C activity

Compounds may be shown to have anti-hepatitis C activity by inhibition of HCV polymerase, by inhibition of other enzymes required in the replication cycle, or by other known methods. Various methods for assaying these activities have been published. the

WO97/12033, filed September 27, 1996, by Emory University, Iisting C. Hagedom and A. Reinoldus are inventors, claiming priority of U.S.S.N. 60/004,383 (September 1995 application), which describes the HCV polymerase assay for evaluating the activity of compounds of the invention. This application and invention belong solely to Triangle Pharmaceuticals, Inc., Durham, North Carolina. Another HCV polymerase assay has been reported by Bartholomeusz et al., "Hepatitis C virus (HCV) RNA polymerase assay using cloned HCV nonstructural proteins"; Antiviral Therapy 1996: 1 (Supp4) 18-24. the

VI. Treatment of Abnormal Cell Proliferation

In alternative embodiments, these compounds are used to treat abnormal cell proliferation. The activity of the compounds can be assessed by conventional screening assays, such as those conducted under the auspices of the National Cancer Institute, or by any other known screening method, such as that described in WO96/07413. the

The extent of anticancer activity of compounds can be readily assessed as follows in the CEM cell or other tumor cell line assay. CEM cells are human lymphoma cells (a T-lymphoblast cell line available from ATCC, Rockville, MD). The toxicity of a compound to CEM cells provides useful information for understanding the activity of the compound on tumors. The toxicity was detected as _IC50 (μM). _IC50 refers to the concentration of the test compound that inhibits the growth of 50% of the tumor cells in the culture medium. The lower the _IC50 , the more active the compound is as an antineoplastic agent. In conclusion, 2'-fluoronucleosides exhibit antitumor activity and can be used to treat abnormal proliferation of cells, if they exhibit toxicity in CEM or other hardy tumor cell lines at concentrations less than 50 μM, more preferably less than 50 μM. 10μM, preferably less than 1μM. Drug solutions, including cycloheximide as a positive control, were placed in 50 μl of growth medium in triplicate at 2 times the final concentration and allowed to equilibrate at 37° C. in a 5% carbon dioxide incubator. Add log phase cells to 50 μl growth medium to a final concentration of 2.5×10 ³ (CEM and SK-MEL-28), 5×10 ³ (MMAN, MDA-MB-435s, SKMES-1, DU-145, LNCap ), 1×10 ⁴ (PC-3, MCF-7) cells/well and incubated 3 (DU-145, PC-3, MMAN), 4 (MCF-7, SK - MEL-28, CEM), or 5 (SK-MES-1, MDA-MB-435s, LNCap) days. Control wells included media alone (blank) and cells plus media without drug. After the growth phase, 15 μl of Cell Titer 96 kit detection dye solution (Promega, Madison, WI) was added to each well and the plate was incubated at 37°C in a 5% carbon dioxide incubator. Add Promega Cell Titer 96 Kit Detection Stop Solution to each well and incubate in this incubator for 4-8 hours. Absorbance was read at 570 nm using a Biotek Biokinetics plate reader (Biotek, Winooski, VT), and medium-only wells were used as blank controls. The average percent inhibition of growth was calculated compared to untreated controls. _IC50 , _IC90 , slope and r-values were calculated by the method of Chou and Talalay. Chou TC, Talalay P. Quantification of dose-effect relationships: synergistic effects of multiple drugs or enzyme inhibitors. Adv Enzyme Regul 1984, 22:27-55.

The active compounds can be used in particular for the treatment of abnormal cell proliferation, and especially cell hyperproliferation. Examples of abnormal cell proliferation include, but are not limited to: benign tumors, including but not limited to papilloma, adenoma, firoma, chondroma, osteoma, lipoma, hemangioma, lymphangioma, leiomyoma, rhabdomyoma, Meningioma, neuroma, ganglioma, nevus, pheochromocytoma, schwannoma, fibroadenoma, teratoma, cystic nevus, granuloma (granuosatheca), Brunner's tumor, androcytoma , hilar cell tumors, sex cord stroma, stromal cell tumors and thyoma and proliferation of smooth muscle cells in the development of plaques of vascular tissue; malignancies (cancers), including but not limited to carcinomas, including renal cell carcinoma, prostate cancer, Bladder cancer and adenocarcinoma, fibrosarcoma, chondrosarcoma, osteosarcoma, liposarcoma, angiosarcoma, lymphangiosarcoma, leiomyosarcoma, rhabdomyosarcoma, myeloid leukemia, erythroleukemia, multiple myeloma, glioma, meningioma , thyoma, phyllodes cystic sarcoma, nephroblastoma, choriocarcinoma teratoma, cutaneous T-cell lymphoma (CTCL), skin tumors that originate in the skin (eg, basal cell tumor, squamous cell tumor , melanoma and Bowen's disease), breast cancer and other tumors invading the skin, Kaposi's tumor and premalignant and malignant diseases of mucosal tissues, including oral, bladder and rectal diseases; preneoplastic lesions, fungal Mycosis, psoriasis, dermatomyositis, rheumatoid arthritis, viral (eg, warts, herpes simplex, and condyloma acuminatum), molluscum contagiosum, premalignant and malignant diseases of the female genital tract (cervical, vaginal, and vulva). These compounds can also be used for drainage. the

In this embodiment, the active compound, or a pharmaceutically acceptable salt thereof, is administered in a therapeutically effective amount to reduce hyperproliferation of target cells. The active compound can be modified to include targeting moieties, which concentrate the compound at the active site. Targeting moieties may include antibodies or antibody fragments that bind target cell surface proteins, including but not limited to epidermal growth factor receptor (EGFR), the c-Esb-2 series of receptors, and vascular endothelial growth factor (VEGF). the

VII. Pharmaceutical Compositions

A patient suffering from any of the diseases described herein may be treated by administering to the patient an effective amount of the active compound, or a pharmaceutically acceptable derivative or salt thereof, in a pharmaceutically acceptable carrier or diluent. The active substances may be administered in liquid or solid form by any suitable route, for example, orally, parenterally, intravenously, intradermally, subcutaneously or topically. For all of the above conditions, the preferred dosage of this compound is about 1 to 50 mg/kg, preferably 1 to 20 mg/kg body weight per day, more generally 0.1 to about 100 mg per kg body weight/day. An effective amount of a pharmaceutically acceptable derivative can be calculated based on the weight of the parent nucleoside to be used. If the derivative is itself active, the effective amount can be estimated by weight of the derivative as described above, or by other means known to those skilled in the art. the

The compound is conveniently administered in any suitable dosage unit, including but not limited to those containing 7 to 3000 mg, preferably 70 to 1400 mg of active ingredient per unit dosage form. Oral dosages of 50-1000 mg are generally convenient. the

Ideally the active ingredient should be used to achieve a peak plasma concentration of active compound of about 0.2 to 70 pM, preferably about 1.0 to 10 pM. This can be achieved, for example, by intravenous injection of a 0.1 to 5% solution of the active compound, optionally in physiological saline, or by bolus injection of the active compound. the

The concentration of active compound in the pharmaceutical composition depends on the rate of absorption, inactivation and excretion of the drug as well as other factors known to those skilled in the art. It is to be noted that such dosage values will also vary with the severity of the condition to be alleviated. It should also be understood that for any particular subject, the specific dosing regimen should be adjusted for a certain period of time according to the needs of the individual and the professional judgment of the person using or suggesting the use of the composition, and the concentrations given herein The ranges are examples only and are not intended to limit the scope or implementation of the claimed compositions. The active ingredient may be administered at once, or may be divided into smaller doses administered at variable intervals. the

The preferred mode of administration of the active compound is oral. Oral compositions generally contain an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For oral therapeutic administration, the active compound can be admixed with excipients and used in the form of tablets, lozenges or capsules. Pharmaceutically acceptable binders and/or excipients may also be part of the composition. the

Tablets, pills, capsules, lozenges, etc. may contain any of the following components or compounds of similar properties: binders such as microcrystalline cellulose, tragacanth or gelatin; excipients such as starch or lactose, disintegrants such as algae acid, Primogel, or cornstarch; lubricants such as magnesium stearate or Sterotes; glidants such as colloidal silicon dioxide; sweeteners such as sucrose or saccharin; or flavoring agents such as menthol, methyl salicylate, or orange flavor spices. When the unit dosage form is a capsule, it may contain, in addition to the above materials, a liquid carrier such as a fatty oil. In addition, dosage unit forms can contain various other materials which modify the physical form of the dosage unit, for example, sugars, shellac, or other enteric agents. the

The compound can be administered as an ingredient in an elixir, suspension, syrup, wafer, gum, or the like. A syrup may contain, in addition to the active compounds, sucrose as a sweetening agent and certain preservatives, dyes and colorings and flavors. the

The compound or its pharmaceutically acceptable derivatives or salts may also be mixed with other active substances which do not impair the desired action, or with substances which supplement the desired action, such as antibiotics, antifungal, anti-inflammatory or other antiviral drugs, including other nucleoside compounds. Solutions or suspensions for parenteral, intradermal, subcutaneous or topical administration may contain the following components: sterile diluents such as water for injection, saline solution, fixed oils, polyethylene glycol, glycerol, propylene glycol or Other synthetic solvents; antimicrobials such as benzyl alcohol or methylparaben; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates, or phosphates and osmotic regulators such as sodium chloride or dextrose. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic. the

If administered intravenously, the preferred carrier is physiological saline or phosphate buffered saline (PBS). the

In a preferred embodiment, the active compounds are formulated with carriers that will protect the compound against its rapid elimination from the body, such as a controlled release formulation, including implants and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, for example, ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such formulations will be apparent to those skilled in the art. These materials are also commercially available from Alza Corporation. the

Liposomal suspensions (including liposomes targeted to infected cells with monoclonal antibodies to viral antigens) are also preferred pharmaceutical carriers. They can be prepared according to methods known to those skilled in the art, for example, as described in US Patent No. 4,522,811 (which is incorporated by reference in its entirety). For example, by dissolving the appropriate lipid(s) such as stearoylphosphorylethanolamine, stearoylphosphorylcholine, arachidylphosphatidylcholine and cholesterol in an inorganic solvent and then evaporating the solvent , leaving a thin film of dry lipid on the surface of the container, a liposome formulation can be prepared. An aqueous solution of the active compound or its monophosphate, diphosphate and/or triphosphate derivatives is introduced into the container. The container is then swirled by hand to release lipid material from the container walls and to disperse lipid agglomerates, thus forming a liposomal suspension. the

The present invention has been described with reference to preferred embodiments. Alterations and modified forms of the invention will become apparent to those skilled in the art from the above description of the invention. the

Claims (10)

1. prepare the method for the acetic ester of end group isomery, may further comprise the steps:

A) make chirality non-carbohydrate sugar encircle the electrophilic source reactant of precursor (4S)-5-(tert-butyl diphenyl siloxy-)-penta-4-lactone and fluorine, form the fluoro lactone:

Wherein TBDPSO is the tertiary butyl-phenylbenzene siloxy-;

B) described fluoro lactone is reduced to the fluoro lactol; And

C) described fluoro lactol acetyl is turned to the acetic ester of end group isomery.

2. the method for claim 1, it also is included in electrophilic source reactant forward direction non-carbohydrate sugar ring precursor (4S)-5-(tert-butyl diphenyl siloxy-)-penta-4-lactone of non-carbohydrate sugar ring precursor (4S)-5-(tert-butyl diphenyl siloxy-)-penta-4-lactone of step in a) and fluorine and adds pair (trimethyl silyl) lithamides (LiHMDS).

3. the process of claim 1 wherein that the electrophilic source of described fluorine is N-fluoro-(two) benzenesulfonimide.

4. the process of claim 1 wherein step in a) chirality non-carbohydrate sugar ring precursor (4S)-5-(tert-butyl diphenyl siloxy-)-penta-4-lactone and the electrophilic source reactant of fluorine before be translated into enolate.

5. the method for claim 1, it comprises that further the acetic ester that makes the end group isomery and purine or pyrimidine bases react to provide β-L-or β-D-2 '-alpha-fluoro nucleosides.

6. the method for claim 5, wherein said base is a kind of purine bases.

7. the method for claim 4, it also comprises makes described enolate and C _1-10The alkyl halide reaction.

8. the process of claim 1 wherein that described fluoro lactone is reduced by diisobutyl alanate (DIBAL-H).

9. the method for claim 5, wherein said β-L-or β-D-2 '-alpha-fluoro nucleosides is β-L-2 '-alpha-fluoro nucleosides.

10. the method for claim 5, wherein said β-L-or β-D-2 '-alpha-fluoro nucleosides is β-D-2 '-alpha-fluoro nucleosides.