GB2147292A - (3-Acylamino)-2-azetidinones - Google Patents

Abstract

Antibacterial activity is exhibited by, optionally further substituted, (3 acylamino)-2-azetidinones having in the 1-position a group of the formula <IMAGE> or a salt or ester thereof wherein R5 and R6 are the same or different and each is hydrogen, halogen, hydroxy, alkoxy, alkylthio, alkyl, substituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, (cycloalkyl)alkyl, (cycloalkenyl)alkyl, phenyl, substituted phenyl, phenylalkyl or (substituted phenyl)alkyl or together R5 and R6 can be =CZ1Z2 wherein Z1 and Z2 are the same or different and each is hydrogen, alkyl, phenyl, or substituted phenyl: and R7 is hydrogen and R8 is hydrogen, hydroxy, alkoxy, alkanoyloxy, or halogen, or together R7 and R8 can be =CZ1Z2 or =O.

Description

SPECIFICATION (3-Acylamino)-2-azetidinones This invention relates to new compounds having the formula

and salts and esters thereof, which exhibit antibacterial activity. In formula I and throughout the specification, the symbols are as defined below.

R1 is an acyl group derived from a carboxylic acid; R2 is hydrogen or methoxy; R3 and R4 are the same or different and each is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, phenyl, substituted phenyl or a 4, 5, 6 or 7-membered heterocycle (referred to hereinafter as Rx) or one of R3 and R4 is hydrogen and the other is azido, halomethyl, dihalomethyl, trihalomethyl, alkoxycarbonyl, 2-phenylethenyl, 2-phenylethynyl, carboxyl, -CH2X1 [wherein X1 is azido, amino (-N H2), hydroxy, alkanoylamino, phenylcarbonylamino, (substituted phenyl) carbonylamino, alkylsulfonyloxy, phenylsulfonyloxy, (substituted phenyl) sulfonyloxy, phenyl, substituted phenyl, cyano,

-S-X2, or -O-X2 (wherein A, X2, X6 and X7 are as hereinafter defined)i, -S-X2 or -O-X2 [wherein X2 is alkyl, substituted alkyl, phenyl, substituted phenyl, phenylalkyl, (substituted phenyl)alkyl, alkanoyl, phenylalkanoyl, (substituted phenyl)alkanoyl, phenylcarbonyl, (substituted phenyl)carbonyl, or heteroaryl carbonyli.

[wherein one of X3 and X4 iS hydrogen and the other is hydrogen or alkyl, or X3 and X4 when taken together with the carbon atom to which they are attached form a cycloalkyl group; and Xs is formyl, alkanoyl, phenylcarbonyl, (substituted phenyl) carbonyl, phenylalkylcarbonyl, (substituted phenyl)alkylcarbonyl, carboxyl, alkoxycarbonyl, aminocarbonyl

(substituted amino)-carbonyl, orcyano (-C=N)], or

(wherein A is -CH=CH-, -(CH2)n-, -CH2-O-, -CH2-NH-, or -CH2-S-CH2-, n is 1 or 2, and X6 and X7 are the same or different and each is hydrogen, alkyl, phenyl or substituted phenyl, or X6 is hydrogen and X7 is amino, substituted amino, acylamino or alkoxy, or X6 and X7 when taken together with the nitrogen atom to which they are attached form a 4, 5, 6 or 7-membered heterocycle); R5 and Re are the same or different and each is hydrogen, halogen, hydroxy, alkoxy, alkylthio, alkyl, substituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, (cycloalkyl)alkyl, (cycloalkenyl)alkyl, phenyl, substituted phehyl, phenylalkyl or (substituted phenyl)alkyl or together R5 and Re can be =CZ1Z2 wherein Z1 and Z2 are the same or different and each is hydrogen, alkyl, phenyl, or substituted phenyl; and R7 is hydrogen and Re is hydrogen, hydroxy, alkoxy, alkanoyloxy, or halogen, or together R7 and Re can be =CZ1Z2 (Z1 and Z2 are defined above) or oxo (=0).

Listed below are definitions of various terms used to describe the p-lactams of this invention. These definitions apply to the terms as they are used throughout the specification (unless they are otherwise limited in specific instances) either individually or as part of a larger group.

The terms "alkyl" and "alkoxy" refer to both straight and branched chain groups. Those groups having 1 to 10 carbon atoms are preferred.

The terms "cycloalkyl" and "cycloalkenyl" refer to cycloalkyl and cycloalkenyl groups having 3, 4, 5, 6 or 7 carbon atoms.

The term "substituted alkyl" refers to alkyl grups substituted with one, or more, azido, amino (-N H2), halogen, hydroxy, carboxy, cyano, alkoxycarbonyl, aminocarbonyl, alkanoyloxy, alkoxy, phenyloxy, (substituted phenyl)oxy, R,-oxy, mercapto, alkythio, phenylthio, (substituted phenyl)thio, alkysulfinyl, or alkylsulfonyl groups.

The terms "alkanoyl", "alkenyl", and "alkynyl"referto both straight and branched chain groups. Those groups having 2 to 10 carbon atoms are preferred.

The terms "halogen" and "halo" refer to fluorine, chlorine, bromine and iodine.

The term "protected carboxyl" refers to a carboxyl group which has been esterified with a conventional acid protecting group. These groups are well known in the art; see, for example, United States patent 4,144,333, issued March 13, 1979. The preferred protected carboxyl groups are benzyl, benzhydryl, t-butyl, and p-nitrobenzyl esters.

The term "substituted phenyl" refers to a phenyl group substituted with 1, 2 or 3 amino (-NH2), halogen, hydroxyl, trifluoromethyl, alkyl (of 1 to 4 carbon atoms), alkoxy (of 1 to 4 carbon atoms), or carboxyl groups.

The expression "a 4,5,6 or 7-membered heterocycle" (referred to as "Rx") refers to substituted and unsubstituted, aromatic and non-aromatic groups containing one or more nitrogen, oxygen or sulfur atoms.

Exemplary substituents are oxo (=0), halogen, hydroxy, nitro, amino, cyano, trifluoromethyl, alkyl of 1 to 4 carbons, alkoxy of 1 to 4 carbons, alkylsylfonyl, phenyl, substituted phenyl, 2-furfurylideneamino

benzylideneamino and substituted alkyl groups (wherein the alkyl group has 1 to 4 carbons). One type of "4,5,6 or 7-membered heterocycle" is the "heteroaryl" group. The term "heteroaryl" refers to those 4,5,6 or 7-membered heterocycles which are aromatic. Exemplary heteroaryl groups are substituted and unsubstituted pyridinyl,furanyl, pyrrolyl,thienyl, 1,2,3,-triazolyl, 1,2,4-triazolyl, imidazolyl, thiazolyl, thiadiazolyl, pyrimidinyl, oxazolyl, triazinyl, and tetrazolyl.Exemplary nonaromatic heterocycles (i.e., fully or partially saturated heterocyclic groups) are substituted and unsubstituted azetinyl, oxetanyl, thietanyl, piperidinyl, piperazinyl, imidazolidinyl, oxazolidinyl, pyrrolidinyl, tetrahydropyrimidinyl, dihyrothiazolyl and hexahydroazepinyl. Exemplary of the substituted 4,5,6 or 7-membered heterocycles are 1-alkyl-3-azetinyl, 2-oxo-1 -imidazolidinyl, 3-alkylsulfonyl-2-oxo-1 -imidazolidinyl, 3-benzylimino-2-oxo-1 -imidazolidinyl, 3-alkyl 2-oxo-1 -imidazolidinyl, 3-phenyl (or substituted phenyl)-2-oxo-1 -imidazolidinyl, 3-benzyl-2-oxo-1 - imidazolidinyl, 3-(2-aminoethyl)-2-oxo-1 -imidazolidinyl, 3-amino-2-oxo-1 -imidazolidinyl, 3- [(alkoxycarbonyl)amino]-2-oxo-1-imidazolidinyl, 3-[2-[(alkoxycarbonyl)-amino]ethyl]-2-oxo-1 -imidazolidinyl, 2-oxo-1 -pyrrolidinyl, 2-oxo-3-oxazol idinyl, 4-hydroxy-6-methyl-2-pyrimidinyl, 2-oxo-1 - hexahydroazepi nyl, 2-oxo-3-pyrrolidinyl, 2-oxo-3-tetrahydrofuranyl, 2,3-dioxo- 1 -pi perazinyl, 2,5-dioxo-1 -piperazi nyl, 4-al kyl-2,3- dioxo-1 -piperazinyl, and 4-phenyl-2-3-dioxo-1 -piperazinyl.

The term "substituted amino" refers to a group having the formula -NY1Y2 wherein Y1 is hydrogen, alkyl, phenyl, substituted phenyl, phenylalkyl or (substituted phenyl)alkyl, and Y2 is alkyl, phenyl, substituted phenyl, phenylalkyl, (substituted phenyl)alkyl, hydroxy, cyano, alkoxy, phenylalkoxy, or amino (-N H2).

The term "acyl" refers to all organic radicals derived from an organic (i.e., a carboxylic acid) by removal of the hydroxyl group. Certain acyl groups are, of course, preferred but this preference should not be viewed as a limitation of the scope of this invention. Exemplary acyl groups are those acyl groups which have been used in the past to acylate ss-lactam antibiotics including 6-aminopenicillanic acid and derivatives and 7-aminocephalosporanic acid and derivatives; see, for example, Cephalosporins and Penicillins, edited by Flynn, Academic Press (1972), German Offenlegungsschrift 2,716,677, published October 1978, Belgian patent 867,994, published December 1978, United States patent 4,152,432, issued May 1, 1979, United States patent 3,971,778, issued July 27,1976, United States patent 4,172,199, issued October23, 1979, and British patent 1,348,894, published March 27, 1974. The portions of these references describing various acyl groups are incorporated herein by reference. The following list of acyl groups is presented to further exemplify the term "acyl"; it should not be regarded as limiting that term. Exemplary acyl groups are: (a) Aliphatic groups having the formula

wherein Ra is alkyl; cycloalkyl; alkoxy; alkenyl; cycloalkenyl; cyclohexadienyl; or alkyl or alkenyl substituted with one or more halogen, cyano, nitro, amino, mercapto, alkylthio, or cyanomethylthio groups.

(b) Carbocyclic aromatic groups having the formula

wherein n is 1, 2 or 3; Rb, Rc, and Rd each is independently hydrogen, halogen, hydroxyl, nitro, amino, cyano, trifluoromethyl, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms or aminomethyl; and Re is amino, hydroxyl, a carboxyl salt, protected carboxyl, formyloxy, a sulfo salt, a sulfoamino salt, azido, halogen, hydrazino, alkylhydrazino, phenylhydrazino, or [(alkylthio)thioxomethyl]thio.

Preferred carbocyclic aromatic acyl groups include those having the formula

(Re is preferably a carboxyl salt or sulfo salt) and

(Re is preferably a carboxyl salt or sulfo salt).

(c) Heretoaromatic groups having the formula

wherein n is 1,2 or 3; Re is as defined above; and Rf is a substituted or unsubstituted 5-, 6- or 7-membered heterocyclic ring containing 1,2,3 or 4 (preferably 1 or 2) nitrogen, oxygen and sulfur atoms. Exemplary heterocyclic rings are thienyl, furyl, pyrrolyl, pyridinyl, pyrazolyl, pyrazinyl, thiazolyl, pyrimidinyl, thiadiazolyl and tetrazolyl.Exemplary substituents are halogen, hydroxyl, nitro, amino, protected amino, cyano, trifluoromethyl, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, or

Preferred heteroaromatic acyl groups include those groups of the above formulas wherein Rf is 2-amino-4-thiazolyl, 2-amino-5-halo-4-thiazolyl, 4-aminopyrimidin-2-yI, 5-amino-l ,2,4-thiadiazol-3-yl, 2- thienyl, 2-furanyl, or 6-aminopyridin-2-yl.

(d) [[(4-Substituted-2,3-dioxo-1-piperazinyl)carbonyl]amino]arylacetyl groups having the formula

wherein Rg is an aromatic group (including carbocyclic aromatics such as those of the formula

and heteroaromatics as included within the definition of Rf); and Rh is alkyl, substituted alkyl (wherein the alkyl group is substituted with one or more halogen, cyano, nitro, amino or mercapto groups), arylmethyleneamino(i.e., -N=CH-Rg wherein Rg is as defined above), arylcarbonylamino (i.e.,

wherein Rg is as defined above) or alkylcarbonylamino.

Preferred [[(4-substituted-2,3-dioxo-1 -piperazinyl)carbonyl]aminojrylacetyl groups include those wherein Rh is ethyl, phenylmethylene-amino or 24urylmethyleneamino.

(e) (Substituted oxyimino)arylacetyl groups having the formula

wherein Rg is as defined above and Rj is hydrogen, alkyl, cycloalkyl, alkylaminocarbonyl, arylamino-carbonyl

wherein Rg is as defined above) or substituted alkyl (wherein the alkyl group is substituted with one or more halogen, cyano, nitro, amino, mercapto, alkylthio, aromatic group (as defined by Rg), carboxyl (including salts thereof), amido, alkoxycarbonyl, phenylmethoxycarbonyl, diphenylmethoxycarbonyl, hydroxyalkoxyphosphinyl, dihydroxyphosphinyl, hyd roxy(phenyl methoxy)phosphinyl, or dialkoxyphosphinyl substi- tuents).

Preferred (substituted oxyimino)arylacetyl groups include those wherein Rg is 2-amino-4-thiazolyl. Also preferred are those groups wherein Ri is methyl, ethyl, carboxymethyl, 1-carboxy-1-methylethyl, 2,2,2- trifluoroethyl or 1 -carboxycyclopropyl.

(f) (Acylamino)arylacetyl groups having the formula

wherein Rg is as defined above and Rj is

amino, alkylamino, (cyanoalkyl)-amino, amido, alkylamido, (cyanoalkyl)amido,

Preferred (acylamino)arylacetyl groups of the above formula include those groups wherein Rj is amino or amido. Also preferred are those groups wherein Rg is phenyl or 2-thienyl.

(g) [[[3-Substituted-2-oxo-1 -imidazolidinyl]ca rbonyl] amino]arylacetyl groups having the formula

wherein Rg is as defined above and Rk is hydrogen, alkylsulfonyl, arylmethyleneamino (i.e., -N=CH-Rg wherein Rg is as defined above),

(wherein R, is hydrogen, alkyl or halogen substituted alkyl), aromatic group (as defined by Rg above), alkyl or substituted alkyl (wherein the alkyl group is substituted with one or more halogen, cyano, nitro, amino or mercapto groups).

Preferred [[3-substituted-2-oxo-1-imidazolidinyl]carbonyl]amino]arylacetyl groups of the above formula include those wherein Rg is phenyl or 2-thienyl. Also preferred are those groups wherein Rk is hydrogen, methylsulfonyl, phenylmethyleneamino or 24urylmethyleneamino.

The terms "salt" and "salts" refer to basic salts formed with inorganic and organic bases. Such salts include ammonium salts, alkali metal salts like sodium and potassium salts (which are preferred), alkaline earth metal salts like the calcium and magnesium salts, salts with organic bases, e.g., dicyclohexylamine salt, benzathine, N-methyl-D-glucamine, hydrabamine salts, salts with amino acids like arginine, lysine and the like. The nontoxic, pharmaceutically acceptable salts are preferred, although other salts are also useful, e.g., in isolating or purifying the product.

The salts are formed in conventional manner by reacting the free acid form of the product with one or more equivalents of the appropriate base providing the desired cation in a solvent or medium in which the salt is insoluble, or in water and removing the water by freeze drying. By neutralizing the salt with an insoluble acid like a cation exchange resin in the hydrogen form (e.g., polystyrene sulfonic acid resin like Dowex 50) or with an aqueous acid and extraction with an organic solvent, e.g., ethyl acetate, dichloromethane or the like, the free acid form can be obtained, and, if desired, another salt formed.

British Application 8320497, published under No. 2123794, discloses p-lactam antibiotics and intermediates having the formula

and salts and esters thereof, wherein R1 is hydrogen or acyl, R2 is hydrogen or methoxy, and R3, R4, R5 and Re are as defined hereinafter. Additionally, the patent application discloses intermediates having the formula

wherein A1 and A2 are amino protecting groups.

As set forth throughout this present specification, p-lactams having in the 1-position an ester of the group

are contemplated as an integral part of this invention. Exemplary esters include alkyl, alkenyl, alkynyl, cycloalkyl, (cycloalkyl)alkyl, Rx-alkyl, trialkylsilylalkyl, mono-, di- or trihaloalkyl, hydroxyalkyl, alkoxyalkyl, carboxyalkyl, alkoxycarbonylalkyl, diphenylmethoxy- carbonylalkyl, carbamoylalkyl, alkylcarbamoylalkyl, dialkylcarbamoylalkyl, indanyl, phenyl, substituted phenyl, phenylalkyl, (substituted phenyl)alkyl, Rx carbonylalkyl,

[wherein Y3 is hydrogen, alkyl or phenyl andY4 iS hydrogen, alkyl, cycloalkyl, (cycloalkyl)oxy, phenyl, or alkoxy, or together Y3 and are -(CH2)2-, -(CH2)3-, -CH=CH-, or

and

esters.

Hydrolyzable esters are those esters that can be hydrolyzed in vivo to give the parent carboxylic acid product; they exhibit the antibiotic activity of the parent carboxylic acid. Non-hydrolyzable esters (esters that do not hydrolze in vivo to the parent carboxylic acid) are contemplated for use in this invention as intermediates; sdme of them are also active as antibiotics.

p-Lactams having a

substituent (or an ester or salt thereof) in the 1-position and an amino or acylamino substituent in the 3-position contain at least one chiral center -- the carbon atom (in the 3-position of th ss-lactam nucleus) to which the amino or acylamino substituent is attached. This invention is directed to those ss-lactams which have been described above, wherein the stereochemistry at the chiral center in the 3-position of the p-lactam nucleus is the same as the configuration at the carbon atom in the 6-position of naturally occurring penicillins (e.g., penicillin G) and as the configuration at the carbon atom in the 7-position of naturally occurring cephamycins, (e.g., cephamycin C).

Also included within the scope of this invention are racemic mixtures which contain the above-described p-lactams.

The ss-lactams of formula I, and salts thereof, have activity against a range of gram-negative and gram-positive organisms. The compounds of this invention can be used as agents to combat bacterial infections (including urinary tract infections and respiratory infections) in mammalian species, such as domesticated animals (e.g., dogs, cats, cows, horses, and the like) and humans.

For combating bacterial infections in mammals a compound of this invention can be administered to a mammal in need thereof in an amount of about 1.4 mg/kg/day to about 350 mglkgiday, preferably about 14 mglkgidayto about 100 mg/kg/day. AIl modes of administration which have been used in the past to deliver penicillins and cephalosporins to the site of the infection are also contemplated for use with the novel family of p-lactams of this invention. Such methods of administration include oral, intravenous, intramuscular, and as a suppository.

The ss-lactams of this invention can be prepared from an amino acid having the formula

The amino group is first protected with a classical protecting group(e.g., t-butoxycarbonyl, benzyloxycarbonyl, o-nitrophenylsulfenyl, etc.), yielding the compound having the formula

In formula Ill, and throughout the specification, the symbol "Al" refers to a nitrogen protecting group. For certain products of formula I, the desired acyl group "R1" can be used as the protecting group "awl" and thus incorporated at the beginning of the reaction sequence.

Reaction of an N-protected amino acid of formula Ill with a compound having the formula

yields a compound having the formula

In formula V, and throughout the specification, the symbol Z3 represents a carboxyl protecting group.

The hydroxyl group of a compound of formula V is converted to a leaving group using, for example, a classical reagent such as methanesulfonyl chloride (methanesulfonyl is referred to hereinafter as "Ms").

The fully protected compound having the formula

is cyclized by treatment with base, e.g., potassium carbonate. The reaction is preferably carried out in an organic solvent such as acetone, under reflux conditions, and yields a compound having the formula

Alternatively, cyclization of a compound of formula V can be accomplished without first converting the hydroxyl group to a leaving group. Treatment of a compound of formula V with triphenyiphosphine and diethylazodicarboxylate or carbon tetrachloride, yields a compound of formula Vli.

Both of the methods disclosed above for ring closure of a compound of formula V result in the inversion of the stereochemistry of the R3 and R4 substituents.

Deprotection of the 3-amino substituent of a compound of formula VII can be accomplished using art-recognized techniques. If, for example, the protecting group is t-butoxycarbonyl, trifluoroacetic acid can be used to deprotectthe amino group. If the protecting group is benzyloxycarbonyl, catalytic (e.g., palladium on charcoal) hydrogenation can be used. If the protecting group is o-nitrophenylsulfenyl,p-toluenesulfonic acid can be used in combination with p-thiocresol. The deprotected compound has the formula

and is a key intermediate for preparing the compounds of this invention. The compounds of formula Vlil form an integral part of this invention.

Well known acylation techniques can be used to convert a compound of formula VIII to the corresponding compound having the formula

Exemplary techniques include reaction with a carboxylic acid (R1-OH) or corresponding carboxylic acid halide or carboxylic acid anhydride. The reactions with a carboxylic acid proceed most readily in the presence of a carbodiimide such as dicyclohexylcarbodiimide and a substance capable of forming a reactive intermediate in situ such as N-hydroxybenzotriazole or N-hydroxysuccinimide. In those instances wherein the acyl group (R1) contains reactive functionality (such as amino or carboxyl groups) it may be necessary to first protect these functional groups, then carry out the acylation reaction, and finally deprotectthe resulting product.

Deprotection of the carboxylic acid group, followed by esterification (if desired), yields the desired products of formula I wherein R2 is hydrogen.

Alternative means are available for converting an intermediate of formula VII to a product of formula I. For example, a compound of formula VII can be reacted with N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) and a silane such as iodotrimethylsilane to cleave the "awl" and "Z3" groups to yield the corresponding 3-trimethylsilylamino compound, which can be acylated using the above-described procedures.

The products of formula I wherein R2 is methoxy can be prepared from the corresponding compound of formula VII. Halogenating (preferably chlorinating) the amide nitrogen of a compound of formula Vll wherein A1 is benzyloxycarbonyl, or benzylcarbonyl, yields a compound having the formula

Reagents and procedures of N-chlorinating amides are well known in the art. Exemplary reagents are tert.

-butyl hypochlorite, sodium hypochlorite, and chlorine. The reaction can be run in an organic solvent (e.g., a lower alkanol such as methanol) or in a two phase solvent system (e.g., water/methylene chloride) in the presence of a base such as sodium borate decahydrate. The reaction is preferably run at a reduced temperature.

Reaction of a compound of formula X with a methoxylating agent, e.g., an alkali metal methoxide, yields a compound (in combination with its enantiomer if R3 and R4 are the same or if X is a racemic mixture) having the formula

The reaction can be run in an organic solvent, e.g., a polar organic solvent such as tetrahydrofuran, at a reduced temperature.

Alternatively, a compound of formula VII can be converted to a compound of formula Xl using a single step procedure. The methoxylating agent can first be mixed with a compound of formula Vll and the N-chlorinating reagent then added to the reaction mixture.

Conversion of a compound of formula Xl to the desired product of formula I can be accomplished using the procedures described above for the conversion of an intermediate of formula VII to a product of this invention.

The starting materials of formula II are readily obtainable using art-recognized procedures; see, for example, Synthesis, pg. 216 (1979) and J. Org. Chem., 44:3967 (1979).

The starting materials of formula IV are obtainable by first reacting a compound having the formula

with a compound having the formula

to yield a compound having the formula

or by first reacting a compound of formula XII with a compound having the formula

to yield a compound having the formula

Hydrolysis of a compound of formula XIV or XVI yields a salt of the corresponding compound having the formula

Partial hydrolysis of a compound of formula XVI by means of HCI yields a salt having the formula

This method is advantageous if the alkyl ester group is a suitable protecting group (Z3).

Before a carboxyl protecting group (Z3) can be added to a compound of formula XVII the amino group must first be protected using conventional techniques. The carboxyl protecting group (Z3) can then be added, and the amino protecting group removed to yield the corresponding starting material of formula IV.

Alternatively, a compound of formula XIII or XV can be reacted with a compound having the formula

wherein Z4 is a leaving group such as chlorine,p-toluenesulfonyl or methanesulfonyl to yield a compound having the formula

Treatment of a compound of formula XX or XXI in the manner described above for the treatment of a compound of formula XIV yields the corresponding starting material of formula IV.

The following examples are specific embodiments of this invention.

Example 1 (3S-trans)-[3-ff[(t-Butyloxy)carb on yl]amin o]-4-methyl-2-oxo- 1-azetidin ylloxy--prnpan oic acid, diphen ylmethyl ester A) N-Phthaloyl-ss-aminoxypropanoic acid A solution of 29.6ml (0.36 mol) of pyridine in 25ml of dry dioxane was dropped into a solution of 26.69 (0.18 mol) of phthalic anhydride and 25.59 (0.18 mol) of p-aminoxyprnpanoic acid hydrochloride in 100 ml of dry dioxane. The mixture was refluxed for 3 to 4 hours and then evaporated in vacuo. The residue was taken up in cold water and adjusted to pH 8 by the addition of sodium carbonate. After extraction with chloroform the aqueous phase was acidified with dilute HCI to pH 2 and then extracted again several times with chloroform. The combined organic layers were dried with CaSO4 and then evaporated in vacuo.The residue was crystallized from hot ethanol, yielding 7.2g of the title compound, melting point 128-139"C (dec).

B) N-Phthaloyl-ss-aminoxypropanoic acid, diphenylmethyl ester A solution of freshly prepared 8.6g (0.044 mol) diphenyldiazomethane in 70ml dioxane was dropped into a solution of 9.5g (0.04 mol) of N-phthaloyl--aminoxyprnpanoic acid in 30ml of dioxane at room temperature.

After stirring overnight and concentration in vacuo, the residue was dissolved in chloroform and washed twice with NaHCO3 solution and then with water Drying over CaSO4, filtration, evaporation of the solvent in vacuo and stirring with petroleum ether (boiling point 40-60"C) yielded 1 5.0g of the title compound as slightly pink crystals, melting point 114-118"C.

C) ss-Aminoxypropanoic acid, diphenylmethyl ester N-phthaloyl-ss-aminoxypropanoicacid, diphenylmethyl ester (16.1g) (0.04 mol) was dissolved in 80ml of dichloromethane and cooled to 0 C. Hydrazine hydrate (3.5ml) (0.072 mol) was added dropwise at 0 C and stirring was continued for 4 hours at room temperature. The precipitated phthalhydrazide was removed by suction and the filtrate was concentrated in vacuo. The residual oil was dissolved in ether, insoluble impurities were filtered off and the solvent was distilled off again in vacuo to give in quantitative yield a syrup which was used directly in the next step.

D) O-l2-HDlohenylmethoxy)carhonyllethyl[-o-N-[(t-hut4oxy)carhon ylJ-L-threonine hydroxamate A solution of 6.339 (0.03 mol) of dicyclohexylcarbodiimide (DCC) in 1 Oml of dry tetrahydrofuran was dropped into a solution of 6.73g (0.03 mol) of N-a-[(t-butyloxy)carbonyl]-L-threonine, 4.719 (0.03 mol) of 1-hydroxybenzotriazole hydrate (HOBT) and 8.33g (0.03 mol) of ss-aminoxypropanoic acid, diphenylmethyl ester in 200ml of dry tetrahydrofuran at 0-5 C. The mixture was stirred overnight at room temperature. The precipitated dicyclohexylurea was removed by filtration and the filtrate was concentrated in vacuo.The residual oil was dissolved in ethyl acetate, insoluble dicuclohexylurea was separated by filtration, and the filtrate was washed five times with 5% NaHCO3 solution, once with aqueous buffer solution pH 4(citrate) and then with water. Drying over MgSO4, followed by filtration and evaporation in vacuo gave 1 2.4g of an oily residue. The oily residue was dissolved in acetonitrile and dried over molecular sieves (3 ), The solvent was removed in vacuo and the crude oil was used in the next step without any further purification.

E) (3S-trans)-f3-[f[(t-Butyloxy)carbon ylj-amin o]-4-meth yl-2-oxo- 1-azetidinylyoxyl-ss-propanoic acid, diphenylmethyl ester Triphenylphosphine (7.58g) (0.029 mol) was added to a solution of 12.41g (0.026 mol) of 0-[2- [(diphenylmethoxy)carbonyl]ethyl]-e-N-[(t-butyloxy)carbonyl]-L-threonine hydroxamate in 130ml of dry acetonitrile. A solution of 6.04ml (0.043 mol) of triethylamine and 2.81 ml (0.029 ml) of carbon tetrachloride in 13ml of dry acetonitrile was added dropwise at room temperature and the mixture was stirred overnight. The solvent was removed in vacuo and the residue was dissolved in chloroform, washed twice with aqueous buffer solution pH 4 (citrate), dried over MgSO4, filtered and evaporated in vacuo.The residue was chromatographed on silica gel, eluting with ether/ethyl acetate (2:1). The fractions which did not contain any triophenylphosphine oxide were combined and concentrated in vacuo and purified by a second chromatography on silica gel eluting with toluene/ether (3:1). Evaporation of the appropriate fractions gave 4.69 of the title compound as a highlyviscosous oil.

Example 2 PSj3a)Z),4(3ji-3-/!(2-A min o-4-thiazolyl)- (m eth oxyimino)acetyljamino]-4-m eth yl-2-oxo -1 1-azetidinylyoxyl-ss- propanoic acid, sodium salt A) (3S-trans)-(3-A mino-4-methyl-2-oxo- 1-azetidinyl)oxyl-ss-propanoic acid, trifluoroacetate sit (3S-trans)-[3-[[[(t-Butyloxy)carbonyl]-amino]-4-methyl-2-oxo-1 -azetidinyl]oxy]-(3-propanoic acid, dipheny Imethyl ester (3.669, 8.05 mmol; see example 1 E) was dissolved in a solution of 1.6ml (1.47 mmol) of anisole in 16ml of trifluoroacetic acid at -10 C. The mixture was evaporated in vacuo (bath temperature 0-5"C) 10 minutes later and the residue was stirred with dry ether.The organic layer was separated from the semi-solid product which was dried in vacuo over P205, yielding 1.179 of the title compound.

B) l3S-f3 (Z), 4p1- ff3- '[(2-A min o-4-thiazolyl)- (methoxyimino)acetyljamino]-4-meth yl-2-oxo- 1-azetidin yl]oxy]- ss-propanoic acid, sodium salt N-Methyl-N-trimethylsilyltrifluoroacetamide (0.93ml, 5.04 mmol) was added to a suspension of 0.48g (1.59 mmol) of (3S-trans)-[(3-amino-4-methyl-2-oxo-1-azetidinyl)oxy]-ss-propanoic acid, trifluoroacetate salt in 6ml of dry acetonitrile/tetrahydrofuran (1:1) at 0 C and stirring was continued for 30 minutes at room temperature.After removing the solvents in vacuo, the oily residue was dissolved in Sml of dry tetrahydrofuran and then added to a mixture of 0.519 (1.59 mmol) of dry (Z)-2-amino-a-(methoxy-imino)-4- thiazoleacetic acid, 1 -hydroxybenzo-triazole ester in 5ml of dry tetrahydrofuran at OOC. After stirring overnight and evaporation in vacuo, the residue was taken up in ether, 1 ml of methanol was added, followed by ice-cold water and the pH of the mixture was adjusted to 6.5 by the addition of NaHCO3 solution. The aqueous layer was separated, washed with additional ether and then freeze-dried.Reverse phase chromatography on HP-20 resin with water as eluent and freeze-drying of the corresponding fractions yielded 210mg of the title compound, melting point > 100"C, dec.

Example 3 [3S-[3ol(Z),4P//-1[3-[[(2-A mino-4thiazolyll 1-carb oxy- 1-meth ylethoxy)iminojacetyljaminoj-4-m eth yl-2-oxo- 1-azetidinylXoxyl-ss-propanoic acid, sodium salt N-Methyl-N-trimethylsilyltrifluoroacetamide (1.11 ml, 6.02 mmol) was added to a suspension of 0.579 (1.9 mmol) of (3S-trans)-[(3-amino-4-methyl-2-oxo-1 -azetidinyl)oxy]-i3-prnpanoic acid, trifluoroacetate salt in 6ml of dry acetonitrile/tetrahydrofuran (1:1) at 0 C. After stirring for 30 minutes at room temperature, the solvents were distilled off in vacuo.The oily residue was dissolved in Smi of dry tetrahydrofuran and then added at room temperature to a reaction mixture of 0.84g (1.9 mmol) of (Z)-2-amino-a-[(1 -diphenyl- methoxycarbonyl-1 -methylethoxy)imino-4-thiazoleacetic acid, 0.3g(1 .9 mmol) of 1-hydroxybenzotriazole and 0.39 (1.9 mol) of dicyclohexylcarbodiimide in 10ml of dry tetrahydrofuran which had been previously stirred for 2 hours at 50 C. Stirring was continued for 3 hours at room temperature, the precipitate was filtered off and the solvent was removed in vacuo.The residue was taken up in ether, 1 ml of methanol was added, followed by ice-cold water and the pH of the mixture was adjusted to 6.5 by the addition of NaHCO3 solution. The aqueous layer was separated and freeze-dried and the resulting [3S-[3a(Z),4ssl]-[[3-[[(2-amino- 4-thiazolyl)[(1 -diphenylmethoxycarbonyl-1 -methylethoxy)imino]acetyl]amino]-4-methyl-2-oxo-1 azetidinyl]oxyl-P-propanoic acid, sodium salt was chromatographed on HP-20 resin eluting with H2O/ acetone. Freeze-drying of the appropriate fractons gave a colorless powder which was added to a - 10 C cold mixture of 3.8ml of trifluoroacetic acid and 0.38ml of anisole.After stirring at room temperature for 30 minutes, the solvent was distilled off in vacuo. Ether and ice-cold water were added and the pH of the mixture was adjusted immediately to 6.5 by the addition of NaHCO3 solution. After freeze-drying of the separated aqueous layer, the crude title compound was purified by reverse phase chromatography on HP-20 resin eluting with water. Freeze-drying of the appropriate fractions gave 0.29g of a colorless solid which decomposed at > 110 C.

Example 4 635-trans)-[[3-[[rPhenylmethoxy)carbonyl]amino]-4-methyl-2-oXo-1-azetidinyl]oxy-ss-propanoicacid, methyl ester A) ss-Aminoxypropanoic acid, methyl ester, hydrochloride A solution of 37.99 (0.44 mol) of methyl acrylate in 100ml of dry dioxane was slowly dropped into a mixture of 41 .3g (0.4 mol) of ethylacetohydroximate and 2.29 (0.04 mol) of sodium methoxide in 400ml of dry dioxane at 20"C. The mixture was stirred for 5 hours at room temperature and then concentrated in vacuo. The residual liquid was taken up in dry ether, filtered and fractionated in vacuo.The fraction bpie 100-1 1 6C was collected and yielded 53.69 of material. 1 8.9g (0.10 mol) of this material was dissolved in 20ml of dry dioxane, 1.8ml (0.1 mol) of water was added and the mixture was saturated with gaseous hydrochloric acid by slight cooling. The clear solution was evaporated in vacuo and the residual oil crystallized after the addition of isopropanol by cooling (-10 C). Ice-cold etherwas added with stirring and the hygroscopic, colorless crystals were collected by suction and dried in vacuo over P2O5, yielding 129 of the title compound.

B) 0-[2-rMethoxycarbonyl)ethyl]-a-N-[Lphenylmethoxy)carbonyl]-L-threonine hydroxamate A solution of 5.079 (0.02 mol) of [(phenylmethoxy)carbonyl]-L-threonine in 15ml of water was dropped into a solution of 4.679 (0.03 mol) of methyl-p-aminoxypropionate, hydrochloride and the pH of the solution was adjusted to 4 - 5 by simultaneous addition of 2N NaOH. With pH control (pH 4 - 5), a solution of 4.229 (0.022 mol) of N-ethyl-N'-(3-dimethylaminipropyl)carbodiimide, hydrochloride in 5ml of water was added and stirring was continued for 3 hours. The reaction mixture was extracted with ethyl acetate and the organic layer was washed successively with 1 N citric acid, 5N NaHCO3 and water and then dried with CaSO4.

Filtration and removal of the solvent in vacuo gave a waxy colorless product.

C) (35-trans) -[f3-J[(Ph en ylmeth ox y) carbon yl]-aminoj-4-meth yl-2-oxo- 1-azetidinylloxy- 1b-propanoic acid, methyl ester Starting from 4.959 (14 mmol) of 0-[2-(methoxyCarbonyl)ethyl]-es-N-[(phenylmethoxy)-carbonyl]l-L- threonine hydroxamate, 4.04g (15.4 mmol) of triphenylphosphine, 3.22ml (23.1 mmol) of triethylamine and 1.50ml (15.5 mmol) of carbon tetrachloride the title compound was prepared using the same conditions as in example 1C. Chromatography of the crude reaction product on silica gel (eluting with toluene) gave a colorless high viscosous oil: yield 2.7g.

Example 5 l3S-[3(Z,,4pll-3-l[(2-A min o-4-thiazolyl)-(m ethoxyimin o)acetyljaminoj-4-meth yl-2-oxo- 1-azetidin ylJoxyl-(3- propanoic acid, methyl ester (3S-trans)-[[3-[[(Phenylmethoxy)carbonyli-amino]-4-methyl-2-oxo-1 -azetidinyl]oxy-t3-prnpanoic acid, methyl ester 0.7659 (2.38 mol) was dissolved in 15ml of dry dimethylformamide and hydrogenated with 0.4g of palladium on charcoal (10%) as catalyst. After 40 minutes, the catalyst was filtered off and the filtrate was added to a solution of 0.769 (2.38 mmol) of (Z)-2-amino-a-(methoxyimino)-4-thiazoleacetic acid,1 - hydroxybenzotriazole ester in 1 Oml of dry dimethylformamide. The mixture was stirred overnight at ambient temperature. The solvent was removed in vacuo, the residue taken up in ethyl acetate, filtered, washed with 5% NaHCO3 solution and dried over CaSO4. Filtration and evaporation in vacuo gave a residue which solidified on stirring with dry ether. Yield 0.469, melting point > 60 C, dec.

Example 6 [35-[3arZ),4ss]J-[[3-[[2-Amino-4thiazolylJ[{1-carboxy- 1-methylethoxyJiminolacetylJamino]-4-methyl-2-oXo- 1 azetidinylioxy'-pornpanoic acid, methyl ester (Z)-2-Amino-a-[(1 -diphenylmethoxycarbonyl-1 -methylethoxy)imino]-4-thiazoleacetic acid (1.05g, 2.38 mmol), 0.37g (2.38 mmol) of 1-hydroxybenzotriazole and 0.499 (2.38 mmol) of dicyclohexylcarbodiimide in 1 Oml of dimethylformamide were stirred for 2 hours at 50"C and the precipitate was removed by suction.

(3S-tra ns)-[[3-[[(Phenylmethoxy)ca rbonyl]-a mino]-4-methyl-2-oxo-1 -azetidinyl]oxyl-P-propanoic acid, methyl ester (0.7659, 2.38 mmol; see example 4) was hydrogenated in 15ml of dry dimethylformamide in the presence of 0.49 of palladium on charcoal (10%) as catalyst (ca. 40 minutes). Both filtrates were combined and stirred overnight at room temperature. After removing the solvent in vacuo, the residue was taken up in ethyl acetate, filtered, washed with 5% NaHCO3 solution and dried over CaSO4.Fitration and evaporation in vacuo gave 1.3g of crude [3S-[3a(Z),4ss]]-[[3-[[(2-amino-4-thiaozly)[(1-diphenylmethoxycarbonyl-1- methylethoxy) im ino]acetyl]a m ino]-4-methyl-2-oxo-1 -azetidinyl]oxy]-p-propanoic acid, methyl ester, which was purified by chromatography on silica gel, eluting with ethyl acetate, and yielding 0.96g of material, melting point > 55 C, dec.

A solution of 2.93m1 oftrifluoroacetic acid and anisole (10:1) was cooled to 10eC and then added to 0.83g (1.33 mmol) of the above azetidine. After stirring at 0 C for 15 minutes the solvent was removed in vacuo (bath temperatures 5"C). The residue was taken up in ether and ice-cold water and the pH was adjusted to 6.5 by addition of NaHCO3 solution. The aqueous layer was separated, washed with ether and freeze-dried. The crude salt was purified by reversed phase chromatography on HP-20 resin eluting with water/acetone.

Freeze-drying of the appropriate fractions and stirring with dry ether gave 0.3959 of the title compound as a colorless solid, dec. > 56 C.

Claims (8)

1. A compound having the formula

or a pharmaceutically acceptable ester or salt thereof, wherein R1 is an acyl group derived from a carboxylic acid; R2 is hydrogen or methoxy; R3 and R4 are the same or different and each is hydrogen, alkyl, alkenyl, alkynyl, cycloalkyl, phenyl, substituted phenyl or a 4, 5, 6 or 7-membered heterocycle, or one of R3 and R4 is hydrogen and the other is azido, halomethyl, dihalomethyl, trihalomethyl, alkoxycarbonyl, 2-phenylethenyl, 2-phenylethynyl, -CH2X1, carboxyl, -S-X2, -O-X2,

wherein X1 is azido, amino, hydroxy, alkanoylamino, phenylcarbonylamino, (substituted phenyl)carbonylamino, alkysulfonyloxy, phenylsulfonyloxy, (substituted phenyl)sulfonyloxy, phenyl, substituted phenyl, cyano,

-S-X2 or -O-X2;; X2 is alkyl, substitued alkyl, phenyl, substituted phenyl, phenylalkyl, (substituted phenylalkyl, alkanoyl, phenylalkanoyl, (substituted phenyl)-alkanoyl, phenylcarbonyl, (substituted phenyl)carbonyl, or heteroarylcarbonyl; one of X3 and X4 iS hydrogen and the other is hydrogen or alkyl, or X3 and X4 when taken together with the carbon atom to which they are attached form a cycloalkyl group; X5 is formyl, alkanoyl, phenylcarbonyl, (substituted phenyl)carbonyl, phenylalkylcarbonyl, (substituted phenyl)alkylcarbonyl, carboxyl, alkoxycarbonyl, aminocarbonyl, (substituted amino)carbonyl, or cyano;A is -CH=CH-, -(CH2)n-, -CH2-O-, -CH2-NH- or -CH2-S-CH2; n is 0, 1 or 2; and X6 and X7 are the same or different and each is hydrogen, alkyl, phenyl or substituted phenyl, or X6 is hydrogen and X7 is amino, substituted amino, acylamino or alkoxy, or X6 and X7 when taken together with the nitrogen atom to which they are attached form a 4, 5, 6 or 7-membered heterocycle;; Re and Re are the same or different and each is hydrogen, halogen, hydroxy, alkoxy, alkythio, alkyl, substituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, (cycloalkyl)alkyl, (cycloalkenyl)alkyl, phenyl, substituted phenyl, phenylalkyl or (substituted phenyl)alkyl, or R5 and Re can together be =CZ1Z2; R7 is hydrogen and Re is hydrogen, hydroxy, alkoxy, alkanoyloxy, or halogen, or R7 and R8 can together be =CZ1Z2oroxo (=0): and Z1 and Z2 are the same or different and each is hydrogen, alkyl, phenyl or substituted phenyl.

2. A compound in accordance with claim 1 wherein R2 is hydrogen.

3. A compound in accordance with claim 1 or 2 wherein R3 and R4 are each independently hydrogen or alkyl.

4. A compound in accordance with claim 1 or 2 wherein R3 and R4 are each independently hydrogen or methyl.

5. A compound in accordance with claim 1,2,3 or 4 wherein R5, Re, R7 and Re are each hydrogen.

6. A compound in accordance with any one of Claims 1 to 5 wherein R1 is

and Ri is methyl, ethyl, carboxymethyl, 1-carboxy-1-methylethyl, 2,2,2-trifluoroethyl or 1carboxycyclopropyl.

7. A compound in accordance with any one of Claims 1 to 5 wherein R1 is

8. A compound in accordance with any one of Claims 1 to 5 wherein R1 is