RU2521593C1 - Mono and difluorosubstituted ethyl (3r,4r,5s)-5-azido-4-acetylamino-3-(1-ethylpropoxy)-cyclohexene-1-carboxylates, method of obtaining and application - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a novel method of obtaining alkyl (3R,4R,5S)-5-azido-3-(1-ethylpropoxy)-4-(mono or difluoro acetylamino)-cyclohex-1-enecarboxylates of general formula 1

and to a method of their application as half-products in synthesis of a nueramidase inhibitor of formula 18

In the said formulas R¹=H,F; R²=C₁-C₃-alkyl. The method of obtaining general formula 1 compounds consists of interaction of alkyl(3R,4R,5S)-5-azido-4-amino-3-(1-ethylpropoxy)-cyclohex-1-enecarboxylate with fluoro- or difluoroactic acid in tetrahydrofuran at room temperature in the presence of hydrochloride of N¹-((ethylamino)methylene)-N³, N³-dimethylpropane-1,3-diamine, 1H-benzo[d][1,2,3]triazol-1-ol and N-ethyl-N-isopropylpropane-2-amine. A compound 18 is obtained by reduction of the compound of general formula 1 with triphenylphosphine in aqueous tetrahydrofuran with the following interaction of the obtained compound with di-Boc-thiourea, hydrolysis of the obtained compound with lithium hydroxide in water dioxane and release of Boc-protection from the obtained acid with 30% solution of trifluoroacetic acid in methylene chloride.

EFFECT: obtaining intermediate products of general formula with application in the claimed method of the said reagents and conditions of reaction makes it possible to carry out the process more purposefully, reduce the quantity of side products and in that way simplify the process of obtaining and separation of the compounds.

4 cl, 5 ex

Description

This invention relates to new alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoro acetylamino) cyclohex-1-enecarboxylates of the general formula 1, to a method for their preparation, to the method of their use as an intermediate of the synthesis of neuraminidase inhibitor

where R ¹ = H, F; R ² = C ₁ -C ₃ alkyl.

Compounds of general formula 4 are known which are effective inhibitors of neuraminidase activity (RF Patent 2469020). Neuraminidase (sialidase, acylneuraminyl hydrolase) is an enzyme common to animals and a number of microorganisms. It is a glycohydrolase that cleaves alpha-ketosidically linked sialic acids from glycoproteins, glycolipids and oligosaccharides. Many of the microorganisms containing neuraminidase are pathogenic to humans and other animals, including poultry, horses, pigs and seals. Such pathogens include the influenza virus. Neuraminidase is associated with the pathogenicity of the influenza virus. Presumably, it promotes the elution of newly synthesized virions from infected cells and the movement of the virus (due to its hydrolase activity) through the mucus of the respiratory tract.

A known method of producing alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoroacetylamino) cyclohex-1-enecarboxylates of the general formula 4 based on alkyl 4-amino-5- (tert-butoxycarbonylamino) -3- (pentan-3-yloxy) cyclohexene-1-carboxylate 2 according to the following scheme 1

The main disadvantage of this scheme is that starting material 2, for example (at R ² = C ₂ H ₅ ), is prepared from ethyl acetate oseltamivir carboxylate 5, the phosphate of which is known as Tamiflu (Oseltamivir Phosphate, Tamiflu) [J.C. Rohloff, K.M. Kent, M.J. Postich, et al. J. Org. Chem. 1998, 63, 4545], which is a known influenza drug [https://integrity.thomson-pharma.com/integrity/xmlxsl/pk_prod_list.xml].

The hydrolysis of oseltamivir 5 gives ethyl (3R, 4R, 5S) -4,5-diamino-3- (pentan-3-yloxy) -cyclohex-1-enecarboxylate 6, which reacts with three Boc-protected anhydride product 2, 7 and 8, one of which (2) is the starting point for the synthesis of target neuraminidase inhibitors (Scheme 2). Of course, the isolation of the required product 2 from a three-component mixture not only complicates the overall process of obtaining neuraminidase inhibitors, but also worsens the economy of this process mainly due to the low yield of compound 2.

Meanwhile, there are known methods for producing an oseltamivir neuraminidase inhibitor using azides as intermediate products with their subsequent reduction with hydrogen on Raney nickel, as in WO 1999014185 (Scheme 3),

or using other reducing agents, as in WO 2011021223 or WO 2009078813.

Moreover, it was previously unknown to obtain alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoroacetylamino) cyclohex-1-enecarboxylates in the synthesis of neuraminidase inhibitors of the general formula 1, or their salts, and it is also not known to use fluorine or difluoro derivatives of acetic acid as acylating agents.

The subject of this invention is a novel alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoro acetylamino) cyclohex-1-encarboxylate of the general formula 1

where R ¹ = H, F; R ² = C ₁ -C ₃ alkyl.

More preferred compounds are ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2-fluoroacetylamino) cyclohex-1-encarboxylate 1 (1) or ethyl (3R, 4R, 5S ) -5-azido-3- (1-ethylpropoxy) -4- (2,2-difluoroacetylamino) cyclohex-1-enecarboxylate 1 (2)

.

.

The subject of this invention is a method for producing a compound of general formula 1, according to which alkyl (3R, 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) cyclohex-1-enecarboxylate 9 is reacted with fluorine or difluoro acetic acid derivative 11 in an organic solvent in the presence of N ¹ - ((ethylamino) methylene) -N ³ hydrochloride, N ⁺ -dimethylpropane-1,3-diamine, 1H-benzo [d] [1,2,3] triazole-1 -ol and N-ethyl-N-isopropyl-propan-2-amine

A more preferred process for preparing the compound of general formula 1 is a process in which tetrahydrofuran is used as an organic solvent and the reaction is carried out at room temperature.

A more preferred method for preparing the compound of general formula 1 is the method according to which ethyl (3R) is used as alkyl (3R, 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) cyclohex-1-enecarboxylate , 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) cyclohex-1-enecarboxylate 9 (1).

The subject of this invention is a new intermediate for the synthesis of a neuraminidase inhibitor of formula 15 or formula 18, which is an alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoro acetylamino) cyclohex-1 carboxylate of the general formula 1

where R ¹ = H, F; R ² = C ₁ -C ₃ alkyl.

"Intermediate" - an intermediate chemical compound obtained as a result of chemical processing or incomplete processing of the starting materials at the intermediate stages of a multi-stage chemical reaction and serving as the feedstock for other substances.

More preferred semi-products and synthesis of a neuraminidase inhibitor are ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2-fluoroacetylamino) cyclohex-1-enecarboxylate 1 (1) or ethyl ( 3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2,2-difluoroacetylamino) cyclohex-1-enecarboxylate 1 (2).

A new intermediate of the synthesis of a neuraminidase inhibitor, representing alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoroacetylamino) cyclohex-1-encarboxylate of the general formula 1, as well as a new the method of its production allows to simplify the technological scheme for the synthesis of a neuraminidase inhibitor and reduce the cost of their production, since the synthesis of the starting product 9, presented below in scheme 5, is unambiguous and is not accompanied, as in the case of the starting product 2, by-product formation:

In this regard, the present invention also provides a method for preparing a compound of general formula 15 using a novel intermediate for the synthesis of a neuraminidase inhibitor, according to which alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoro acetylamino) cyclohex-1-enecarboxylate of the general formula 1 is reduced with triphenylphosphine

Best results are achieved if the reduction of alkyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (mono or difluoro acetylamino) cyclohex-1-enecarboxylate of general formula 1 is carried out in aqueous tetrahydrofuran.

Another subject of the present invention is a method for producing a compound of general formula 18, according to which a compound of general formula 15, obtained using a new intermediate of the synthesis of a neuraminidase inhibitor according to this invention, is subjected to further interaction, which includes the following stages:

(a) reacting a compound of general formula 15 with di-Boc-thiourea to form a compound of formula 16,

(b) hydrolysis of a compound of formula 16 to form an acid of formula 17,

(b) removing the Boc protection from the acid of formula 17 to form a compound of general formula 18

Compounds 18 are also active inhibitors of neuraminidase, including influenza virus H5N1 neuraminidase [Application for patent of the Russian Federation 2012119272, priority from 05/12/2012].

Best results are achieved if the hydrolysis of a compound of formula 16 is carried out in aqueous dioxane with lithium hydroxide.

Best results are achieved if the removal of Boc-protection from the acid of formula 17 is carried out with a 30% solution of trifluoroacetic acid in methylene chloride.

The invention is illustrated, but not limited to the following examples.

Example 1. Obtaining ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2-fluoroacetylamino) cyclohex-1-enecarboxylate 1 (1). To a solution of 34.4 g of the starting ethyl (3R, 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) cyclohex-1-enecarboxylate 9 (1) in 344 ml of THF is added N ¹ - ((( ethylamino) methylene) -N ³ , N ³ -dimethylpropan-1,3-diamine (26.64 g), 1H-benzo [d] [1,2,3] triazol-1-ol (18.64 g), N-ethyl- N-isopropylpropan-2-amine (49.4 g; 66.67 ml) and then pinned while cooling in an ice bath 10.88 g of 2-fluoroacetic acid. The reaction mass is stirred at room temperature overnight. At the end of the reaction, the solvent was distilled off, the resulting oil was dissolved in EtOAc, washed with 5% NaHCO ₃ solution, dried over Na ₂ SO ₄ and in vacuo. Purification of the product is carried out by flash chromatography in an EtOAc / Hex 1 to 1 system. If necessary, recrystallization from 5% EtOAc in heptane is carried out. The yield of ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2-fluoroacetylamino) cyclohex-1-enecarboxylate 1 (1) was 25.7 g. LC-MS (M + H ) ⁺ 357. ¹ H NMR (CDCl ₃ ), 400 MHz: 6.81 (s, 1H), 6.55 (s, 1H), 4.83 (d, J = 47.2 Hz, 2H), 4.49 (d, J = 8.8 Hz, 1H), 4.23 (m, 3H), 3.61 (q, J = 8.4 Hz, 1H), 3.34 (m, 1H), 2.92 (m, 1H), 2.32 (m, 1H), 1.52 (m, 4H), 1.32 (t, J = 6.8 Hz, 3H), 0.91 (m, 6H).

Example 2. Obtaining ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2,2-difluoroacetylamino) cyclohex-1-enecarboxylate 1 (2). To a solution of 34.4 g of the starting ethyl (3R, 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) cyclohex-1-enecarboxylate 9 (1) in 344 ml of THF is added N ¹ - ((( ethylamino) methylene) -N ³ , N ³ -dimethylpropan-1,3-diamine (26.64 g), 1H-benzo [d] [1,2,3] triazol-1-ol (18.64 g), N-ethyl- N-isopropylpropan-2-amine (49.4 g; 66.67 ml) and then dropwise added with cooling in an ice bath 11.5 g of 2,2-difluoroacetic acid. The reaction mass is stirred at room temperature overnight. At the end of the reaction, the solvent was distilled off, the resulting oil was dissolved in EtOAc, washed with 5% NaHCO ₃ solution, dried over Na ₂ SO ₄ and in vacuo. Purification of the product is carried out by flash chromatography in an EtOAc / Hex 1 to 1 system. If necessary, recrystallization from 5% EtOAc in heptane is carried out. The yield of ethyl (3R, 4R, 5S) -5-azido-4- (2,2-difluoroacetamido) -3- (pentan-3-yloxy) cyclohex-1-enecarboxylate 1 (2) was 25.1 g. LC-MS ( M + H) ⁺ 375. ¹ H NMR (DMSO-d ⁶⁾ 400 MHz: 9.03 (d, J = 8Hz, 1H), 6.65 (c, 1H), 6.29 (t, J = 53.2 Hz, 1H) , 4.24 (w, 1H), 4.16 (m, 2H), 3.82 (m, 2H), 3.35 (m, 1H), 2.81 (m, 1H), 2.21 (m, 1H), 1.41 (m, 4H), 1.23 (t, J = 7.2 Hz, 3H), 0.84 (t, J = 7.2 Hz, 3H), 0.76 (t, J = 7.2 Hz, 3H). Ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2,2-difluoroacetylamino) cyclohex-1-encarboxylate mesylate 1 (2) * CH ₃ SO ₃ H is prepared by the addition of methanesulfonic acid to a solution of 1 (2) in dichloromethane. If necessary, additional recrystallization of the obtained mesylate is carried out.

Example 3. Obtaining ethyl (3R, 4R, 5S) -5-amino-3- (1-ethylpropoxy) -4- (2-fluoroacetamido) cyclohex-1-enoxoxylate 15 (1) using a new intermediate for the synthesis of a neuraminidase inhibitor. To a solution of 2 g of ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2-fluoroacetylamino) cyclohex-1-encarboxylate 1 (1) in a mixture of 20 ml of THF and 5 ml water add 1.62 g of triphenylphosphine. The reaction mass is stirred for 3 hours at room temperature and then 3 hours at 70 ° C. Monitoring the progress of the reaction is carried out by the LC-MS method. At the end of the reaction, the solvents are distilled off, the resulting oil is dissolved in a small amount of diethyl ether and the precipitated triphenylphosphine oxide is filtered off. The residue was dried in vacuo. Ethyl 5-amino-4- (2-fluoroacetamido) -3- (pentan-3-yloki) cyclohex-1-encarboxylate 15 (1), LC-MS (M + H) ⁺ 331 was obtained.

Example 4. Obtaining ethyl (3R, 4R, 5S) -5-amino-4- (2,2-difluoroacetamido) -3- (pentan-3-yloki) cyclohex-1-enecarboxylate 15 (2) using a new synthesis intermediate neuraminidase inhibitor. To a solution of 24 g of ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2,2-difluoroacetylamino) cyclohex-1-enecarboxylate 1 (2) in a mixture of THF and water is added 10.62 g of triphenylphosphine. The reaction mass is stirred for 3 hours at room temperature and then 3 hours at 70 ° C. Monitoring the progress of the reaction is carried out by the LC-MS method. At the end of the reaction, the solvents are distilled off, the resulting oil is dissolved in a small amount of diethyl ether and the precipitated triphenylphosphine oxide is filtered off. The resulting material was separated on a column. 9.8 g of compound 15 (2) are obtained. LC-MS (M + H) ⁺ 349. The mesylate is prepared by adding methanesulfonic acid to a solution of product 15 (2) in dichloromethane. If necessary, additional recrystallization of the obtained mesylate is carried out.

Example 5. Obtaining (3R, 4R, 5S) -4- (2-fluoroacetamido-5-guanidino-3- (pentan-3-yloxy) cyclohexene-1-carboxylic acid 18 (1) using a new intermediate for the synthesis of a neuraminidase inhibitor. To a solution of ethyl (3R, 4R, 5S) -5-amino-3- (1-ethylpropoxy) -4- (2-fluoroacetamido) cyclohex-1-enoxoxylate 15 (1) (46.6 g) in 466 ml of DMF, cooled to -10 ° C, triethylamine (78.4 g), N, N′-di-boc-thiourea (41.47 g) are added, then mercury (II) chloride (45.92 g) is added in portions, not allowing the reaction mass to warm up. stirred for 1.5 hours while cooling. and the precipitate is filtered through celite, DMF is distilled off in vacuo, the resulting oil is dissolved in ethyl acetate, washed with 5% NaHCO ₃ solution, dried over Na ₂ SO ₄ , filtered and dried in vacuo The resulting oil is filtered through a 300 ml silica gel layer, washing with ethyl acetate. The mother liquor is dried in vacuo, the resulting oil is triturated in a small amount of hexane, and the precipitate formed is filtered off, washed with hexane and dried in air. Yield (3R, 4R, 5S) -ethyl 5 - ((Z) -2,3-bis (tert-butoxycarbonyl) guanidino) -4- (2-fluoroacetamido) -3- (pentan-3-yloxy) cyclox-1 -carboxylate 16 (1) was 48.6 g. To a solution of 46.8 g (3R, 4R, 5S) -ethyl-5 - ((Z) -2,3-bis (tert-butoxycarbonyl) guanidino) -4- (2-fluoroacetamido ) -3- (pentan-3-yloxy) cyclox-1-enecarboxylate 16 (1), 483 ml of dioxane are added 243 ml of a 5% solution of lithium hydroxide and the reaction mixture is stirred at room temperature for 30 minutes. Then lithium hydroxide is passivated by adding a small excess of acetic acid. Solvents are flashed in vucoum (residual water is removed by azeotropic distillation with dioxane, and acetic acid with toluene), the dry residue is extracted with acetonitrile, the combined extract is dried over Na ₂ SO ₄ and in vacuum. The resulting product 17 (1) is used in further reactions without further purification. The yield of product 17 (1) is approaching quantitative. The resulting (3R, 4R, 5S) -5 - ((Z) -2,3-bis (tert-butoxycarbonyl) guanidino) -4- (2-fluoroacetamido) -3- (pentan-3-yloxy) cyclohex-1- encarboxylic acid 17 (1) (45 g) was dissolved in 450 ml of a 30% solution of trifluoroacetic acid in methylene chloride and stirred at room temperature for 12 hours. Then methylene chloride is distilled off in vacuo at room temperature, the residue is dissolved in 300 ml of water and alkalized by adding a concentrated solution of sodium carbonate. The precipitated white precipitate is filtered off, washed with water, acetone, diethyl ether and dried in air. (3R, 4R, 5S) -4- (2-fluoroacetamido-5-guanidino-3- (pentan-3-yloxy) cyclohexene-1-carboxylic acid 18 (1) is obtained, which, if necessary, is recrystallized to give a product with a basic content 99.1-99.5%. LC-MS (M + H) ⁺ 345. Compound 18 (1) (approximately 14 g) was dissolved in 140 ml of dioxane and an equivalent amount of methanesulfonic acid was added. The precipitated mesylate was filtered off, washed with ether and dried in vacuo. The yield of acid mesylate 18 (1) * CH ₃ SO ₃ H is 15.1 g with a purity of 98-99%.

In a similar manner, (3R, 4R, 5S) -4- (2,2-difluoroacetamido-5-guanidino-3- (pentan-3-yloxy) cyclohexene-1-carboxylic acid 18 (2) and its mesylate are obtained.

Claims (4)

1. The method of obtaining the compounds of General formula 1 by the interaction of alkyl (3R, 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) -cyclohex-1-enecarboxylate of the formula 9 with fluoro- or difluoroacetic acid 11 in tetrahydrofuran at room temperature in the presence of N ¹ - ((ethylamino) methylene) -N ³ hydrochloride, N ³ -dimethylpropane-1,3-diamine, 1H-benzo [d] [1,2,3] triazol-1-ol and N ethyl N-isopropyl-propan-2-amine

where R ¹ = H, F; R ² = C ₁ -C ₃ alkyl. 2. The method according to claim 1, where the resulting compound is ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2-fluoroacetylamino) cyclohex-1-encarboxylate of the formula 1 ( 1) or ethyl (3R, 4R, 5S) -5-azido-3- (1-ethylpropoxy) -4- (2,2-difluoroacetylamino) cyclohex-1-enecarboxylate of the formula 1 (2)

3. The method according to claim 1, characterized in that ethyl (3R, 4R) is used as alkyl (3R, 4R, 5S) -5-azido-4-amino-3- (1-ethylpropoxy) cyclohex-1-enecarboxylate , 5S) -5-azido-4-amino-5- (1-ethylpropoxy) cyclohex-1-enecarboxylate of formula 9 (1) . 4. A method for producing a compound of general formula 18 by reducing a compound of general formula 1 obtained by the method according to claim 1 with triphenylphosphine in aqueous tetrahydrofuran and subsequent reaction of a compound of general formula 15 with di-Boc-thiourea followed by hydrolysis of a compound of formula 16 with lithium hydroxide in aqueous dioxane and removal of the Boc protection from the acid of formula 17 with a 30% solution of trifluoroacetic acid in methylene chloride

where R ¹ = H, F; R ² = C ₂ H ₅ .