IE46280B1 - -lactam derivatives - Google Patents

Abstract

The present invention relates to novel 3.beta.-amino or 3.beta.-acylamino-4.alpha.-acetoxyazetidinone compounds which are useful antibacterials for controlling .beta.-lactamase producing gram-negative bacteria and other pathogens, or are useful intermediates in the preparation of said antibiotics, and to a novel process for the preparation of said compounds.

Description

This invention relates to β-lactam derivatives, and more particularly it relates to novel 3p-amino or 38-acylamino-4a-acetoxyazetidinone compounds which are useful antibacterials for controlling β-lactamase producing gram-negative bacteria and other pathogens, or are useful intermediates in the preparation of said antibiotics, and to a novel process for the preparation of said compounds.

This invention is particularly concerned with β-lactam antibiotics. In particular, it relates to monocyclic β-lactam antibiotics which are 3p-acylaminoazetidin-2-ones.

The penicillins and cephalosporins are well known β-lactam antibiotics which are bicyclic compounds containing a fused ring system. Th6 penicillins have the 4-membeted β-lactam ring fused to a thiazolidine ring while in the cephalosporins, the β-lactam ring is fused to a dihydrothiazine ring. Monocyclic β-lactam antibacterial compounds are less well known. The monocyclic β-lactam antibiotic, nocardicin, has been recently discovered and is described in Belgium Patent No. 830,934 and by H. Aoki, et al., 15th Interscience Conference on Antimicrobial Agents and Chemotherapy, Abst. No. 97, Sept. 1975.

Nocardicin,has the following structural formula.

H HOOC-CH-CHs-CHe-O-/ S-C-C-N-f I II I NHa N / I w OH In view of the importance of β-lactam antibiotics in the treatment of infectious diseases, considerable effort is directed by microbiologists and chemists to the discovery T I .·N-C-·/ ^*-0H -246280 and development of other, β-lactam antibiotics which possess activity against a broader spectrum of microorganisms or which are more effective than the currently available antibiotics.

The present invention provides 4a-acetoxyazetidin2-one compounds of the formula II wherein a and a' independently are hydrogen, halogen, hydroxy, protected hydroxy, C^-C^ alkyl, C1“C<} alkoxy, amino, protected amino, aminomethyl or protected aminomethyl; R ,is amino or an acylamino group; and is hydrogen or a carboxylic acid protecting group; and when is hydrogen the pharmaceutically acceptable non-toxic salts thereof.

The present invention also provides a process for preparing a 4a-acetoxyazetidin-2-one compound of the formula K~ D-C-CHs COORi wherein R is amino or an acylamino group; R^ is hydrogen or a carboxylic acid protecting group; and a and a' indepen20 dently are hydrogen, halogen, hydroxy, protected hydroxy, -346280 C1~C4 alkyl, C1~C4 alkoxy, amino, protected amino, aminomethyl or protected amino methyl; which comprises heating a thiazolidine azetidinone compound of the formula wherein Ra is C^-C^ alkyl, phenyl, benzyl or phenoxymethyl; and R^, a and a' are as defined above; with mercuric acetate in the presence of acetic acid to form a N-propenyl 4a-acetoxyazetidin-2-one amide of the formula I . « CHa I 0 .

CzCI-te 11 II I O-C-CHa Ra-C—N—f—T ,, . . A HI Λα COORi wherein Ra, R^, a and a' are as defined above; hydrolyzing the 4a-acetoxyazetidin-2-one amide to form a 4a-acetoxyazetidin-2-one of the formula II ^O-C-CHa IV COORi a' wherein Ra, R^, a and a' are as defined above; if desired cleaving by conventional methods the 3-position acyl group to provide a compound of formula I wherein R is -446280 amino; if desired reacylating the 3-amino-4a-azetidin2-one compound so obtained by conventional methods; and optionally removing the carboxy, hydroxy or amino protecting groups.

When in the above formula R is an acylamino group, it preferably is a group of the formula H ll I R'-C-N10 wherein R' is C^-C^ alkyl, cyanomethyl, bromomethyl, chloromethyl, phenyl, or a group of the formula Z 11 x·—V Ra-0-C-CH-CHs-CH2-0-*f S-CI \=· NH ' Ψ wherein Ra is hydrogen, benzyl, diphenylmethyl or 4-methoxybenzyl; Rb is hydrogen or an amino-protecting group of the fonnula ll rc-O_Cwherein Rc. is t-butyl, 2,2,2-trichloroethyl, benzyl, 4-nitrobenzyl, cyclopentyl, or cyclohexyl; z is =o or =N-OZ', wherein 2' is hydrogen, acetyl, chloroacetyl, triphenylmethyl or p-methoxybenzyl; or R' is a group of the formula r-ch2-546280 wherein R1' is a phenyl group of the Eormula wherein b and b' independently are hydrogen, halogen, hydroxy, C^-C^ alkyl, C^-C^ alkoxy, amino or aminomethyl; or R11 is thienyl, furyl, thiazolyl, oxazolyl, isothiazolyl, tetrazolyl, or an isoxazolyl group of the formula wherein d is hydrogen, methyl, or a group of the formula wherein b and b' have the same meanings defined above, and d* is hydrogen, methyl, or chloro; or R' is a phenoxymethyl group of the formula >-O-CHawherein b and b' have the same meanings as defined above; or R1 is a group of the formula R'''-S-CH2-646280 wherein 11'1' is a group of the formula wherein b and b* are as defined above, 4-pyridyl, thiazolyl, thiadiazolyl, or oxadiazolyl; or R' is a group of the formula H I R-''-ΟΙ wherein R' ’ * ’ is a phenyl group of the formula wherein b and b' are as defined above, thienyl or furyl; and Q is amino, hydroxy, carboxy, -SO3H, or -NH-SOgH, or any of these groups in protected form; or R1 is a group of the formula R -CII N I I wherein R'1'' has the same meanings as defined above and Z1' is hydrogen, acetyl or methyl; or R' is a group of the formula -746280 II I R*'''-ΟΙ N-H I C=0 I . Y wherein R’' 1 1 is as defined above and Y is a dimethylureido group of the formula CHa 0 H I II I - N - C - N - CHa , an imidazolidin-2-one group YII wherein Y' is hydrogen, C1~C4 alkyl, C2~C4 alkanoyl or methanesulfonyi; or an N-methylacyl group of the formula CHa 0 ' - N - C - Y wherein Y'* is C^-C4 alkyl, or a group of the formula —(CH=CH)n—/ wherein n = 0 or 1 and a'' is hydrogen, nitro, or chloro. -846280 The phenyl group represented in the above definition by the formula typically represents phenyl, 4-hydrcxyphenyl, 4-(tetrahydropyran-25 yloxy)phenyl, 4-benzyloxyphenyl, 3-hydroxyphenyl, 3,4dihydroxyphenyl, 4-chlorophenyl, 3,4-dichlorophenyl, 2,6dichlorophenyl, 3-bromophenyl, 3-chloro-4-hydroxyphenyl, 3-chloro-4-methylphenyl, 4-t-butylphenyl, 3,4-dimethylphenyl, 2,4-dimethylphenyl, 4-ethylphenyl, 3-methyl-410 hydroxyphenyl, 4-aminophenyl, 3-aminophenyl, 3-amino-4methylphenyl, 2-aminomethylphenyl, 4-aminomethylphenyl, 4methoxyphenyl, 2,6-dimethoxyphenyl, 3-ethoxy-4-hydroxyphenyl, 4-isopropoxyphenyl, 4-chloro-2-aminomethylphenyl, 3bromo-4-methoxyphenyl, or 3-methy1-4-aminophenyl.

The phenyl group represented in the above formula by b. typically represents phenyl, 4-chlorcphenyl, 3,4-dichlorophenyl 3- bromophenyl, 3-chloro-4-hydroxyphenyl, 4-hydroxyphenyl, 2o 3-hydroxyphenyl, 3,4-dihydroxyphenyl, 4-methylphenyl, 4- t-butylphenyl, 4-ethylphenyl, 4-methoxyphenyl, 3-ethoxy4-hydroxyphenyl, 4-aminophenyl, 4-aminomethylphenyl, 3-methyl4-aminophenyl, 2,6-dimethoxyphenyl, or 3-brano-4-methax:yphenyl.~ -9, 46280 Illustrative Of the amino-protecting groups defined 0 c in the above formula I by the formula R -O-C- are t-butyloxycarbonyl, 2,2,2-trichloroethoxycarbonyl, benzyloxycarbonyl, p-nitrobenzyloxycarbonyl, cyclopentyloxycarbonyl and cyclo5 hexyloxycarbonyl.

As used herein the term thienyl refers to both 2thienyl and 3-thienyl; thiazolyl refers to 2-thiazolyl and -thiazolyl; tetrazolyl refers to 1- and 2-tetrazolyl; thiadiazolyl refers to 1,3,4-, 1,2,5- and 1,2,4-thiadiazoll0 5-yl; and oxadiazolyl refers to 1,3,4-oxadiazolyl.

Examples of isoxazolyl groups represented in the above formula I by are 3-methylisoxazol-5-yl, 3,4-dimethylisoxazol-5-yl, 415 chloroisoxazol-5-yl, 3-phenyl-4-chloroisoxazol-5-yl, 3(4-chlorophenyl)isoxazol-5-yl, 3-(2-chlorophenyl)isoxazol5-yl, 3-(2-chlorophenyl)-4-methylisoxazol-5-yl, 3-(2,6dichlorophenyl)isoxazol-5-yl, 3-(2,6-dichlorophenyl)-4methylisoxaz0l-5-yl, isoxazole-5-yl, 3-(2,4-dimethyl2Q phenyl)-4-methylisoxazol-5-yl, 3-(2,6-dimethylphenyl)4-chloroisoxazol-5-yl, 3-(4-methoxyphenyl)isoxazol-5-yl, 3-(2,6-dimethoxyphenyl)-4-chloroisoxazol-5-yl, 3-(3chloro-4-hydroxyphenyl)-4-methylisoxazol-5-yl, 3-methyl-5chloroisoxazol-4-yl, 3,5-dimethylisoxazol-4-yl, 3-phenyl25 isoxazol-4-yl, 3-(4-chlorophenyl)-5-methylisoxazol-4-yl, 3-(2-chlorophenyl)-5-chloroisoxazol-4-yl, and 3-(2,6-dimethcKyphenyl)-5-methylisoxazol-4-yl, -1046280 The compounds of the formula I can be characterized as monocyclic β-lactam antibiotics or as azetidin2- ones which are substituted in the 1-position with an acarboxybenzyl or α-carboxy-substituted benzyl group and in the 3-position by a β-amino or β-acylamino group and which also are substituted in the 4-position with an acetoxy group.

The thiazolidine azetidinone starting material represented by the formula II is prepared according to the following method. L-cysteine is reacted with dry acetone at the reflux temperature to provide 2,2-dimethyl-4-thiazolidinecarboxylic acid. The product is acylated with an acyl chloride in the presence of propylene oxide to provide 3- acyl-2,2-dimethyl-4-thiazolidinecarboxylic acid represented by the following formula. 0 CHax zCH3 11 /’\ Ra-C--II COOH wherein Ra is as defined above.

The thiazolidinecarboxylic acid is coupled with an ester of a phenylglycine represented by the formula, HeN-C— I , COORi wherein a, a*, and R^ are as defined herein to form the amide represented by the following formula -1146280 HaC^ ^CHa uA The coupling reaction is carried out by first preparing the active ester of the thiazolidinecarboxylic acid formed with 1-hydroxybenzotriazole (HBT). The active ester then is reacted with the phenylglycine ester in the presence of dicyclohexylcarbodiimide.

Phenylglycine esters which can be used to form the above amides include for example, benzyl phenylglycinate, 4methoxybenzyl phenylglycinate, benzyl 4-methoxyphenyl]jq glycinate, benzyl 4-chlorophenylglycinate, benzyl 3,4dimethylphenylglycinate, benzyl 4-hydroxyphenylglycinate, 2,2,2-trichloroethyl phenylglycinate, 4-methoxybenzyl 3-chloro-4-hydroxyphenylglycinate, benzyl 4-t-butylphenylglycinate, benzyl 4-aminophenylglycinate, and 2,2,2-tri15 chloroethyl 3,4-dichlorophenylglycinate. When the phenylglycine ester is substituted with a reactive functional group which can interfere with the desired coupling reaction (N-acylation), for example, a phenolic OH group or an amino group, such groups are blocked during the amidation reaction and in subsequent reactions in the process. The amino group can be blocked with the t-butyloxycarbonyl (t-BOC) group or the benzyloxycarbonyl group. A phenolic hydroxy substituent is best blocked with the benzyl group or tetrahydropyran group. -124 6 2 8 0 The thiazolidine amide of the above formula is then heated at the reflux temperature in a hydrocarbon solvent such as benzene or toluene with benzoyl peroxide to form the 5a-benzoate derivative represented by the formula ,CHs Ra I... o-c—·; lii-H »—·κ < > ·ζζ· :OOR1 a* The benzoate is reacted in methylene chloride at about 0°C. with hydrogen chloride to form the corresponding 5achloro compound by replacement of the benzoate function.

The 5a-chloro amide is reacted with sodium hydride under anhydrous conditions in a halogenated hydrocarbon solvent, such as methylene chloride, at a temperature between about 0°C. and about 30°C. to effect an intramolecular cyclization and provide the substituted thiazolidine azetidin-2-one represented by the following formula.

HaC^ zCH3 COORi ° For convenience the compounds of the above formula arc referred to heroin as thiazolidine azetidinone derivatives. These compounds formally are named 2-acyl-3,3dialkyl-7-οχο-α-[substituted phenyl]-4-thia-2,6-diazabicyclo[3.2.0]heptane-6-acetic acid esters. -1346280 .τ The compounds of formula I arc? prepared by the process outlined .above'. The reaction cif the thiazolidine azetidinone with mercuric acetate is carried out in acetic acid or in an inert co-solvent with acetic acid. Co-solvents 5 such as tetrahydrofuran, dioxane, dimethylformamide, or dimethylacetamide can be used. A large excess of acetic acid is employed while between 1 mole and 3 moles of mercuric acetate per mole of the thiazolidine azetidinone is used. Preferably, 1.5 to 2.0 moles of mercuric acetate per mole of starting material is employed.

The reaction preferably is carried out in acetic acid with heating at a temperature between 25° and 75eC.

The reaction mixture is filtered after the reaction is complete to remove insoluble mercury compounds and the filtrate is evaporated. The product is then extracted from the residue with a water immiscible organic solvent such as ethyl acetate. The product, a N-propenylamide of the foregoing formula ill, need not be purified for its hydrolysis to the amide. The hydrolysis is best carried out between 2o 15° and 55°C. in a water-miscible solvent, for example, tetrahydrofuran, with dilute hydrochloric acid, for example, between 2 percent and 10 percent hydrochloric acid. Dilute sulfuric or dilute phosphoric acid also can be used. Alternatively, the hydrolysis is carried out in aqueous tetrahydrofuran, preferably 50% aqueous tetrahydrofuran, with mercuric acetate. Preferably an amount of mercuric acetate equal in weight to the amount of N-propertylamine is employed. The hydrolysis can be carried out at a temperature between 15°C. and 45°C. and preferably at 20°C. to 25°Ό. -1446280 After the hydrolysis of the N-propenylamide is complete, the reaction mixture is evaporated and the residue containing the product is dissolved in a water immiscible solvent such as ethyl acetate and the solution is washed with a dilute base such as sodium bicarbonate to remove traces of acid. The product, an ester of 1-[a-(carboxy)benzyl or substituted benzyl]-33-acylamido-4a-acetoxyazetidin-2-one represented by the foregoing formula IV is recovered from the washed solution and can be further purified by chromatography over silica gel.

The 3fS-amino-4a-acetoxyazetidin-2-ones are prepared from the 3'3-acylamido-4a-acetoxy hydrolysis product via N-deacylation by conventional methods? for example by reaction with phosphorous pentachloride in the presence of pyridine to form the intermediate acylimido chloride; reaction with methanol to form the acylimido ether; and hydrolysis of the ether.

The 3p-acylaminoazetidin-2-ones represented by the formula I wherein R is an acylamino group of the formula 0 H '· ι R'-C-N- are prepared via the acylation of the 33-amino out nucleus compounds. The acylation is carried/by methods which commonly are employed in the cephalosporin and penicillin art. The acylation is best carried out with an active derivative of the carboxylic acid R'-COOH. Active derivatives of these acids include the acyl halides such as the acid chlorides or bromides, the acid azides, and the mixed anhydrides formed with methyl chloroformate, ethyl chloroformate, or iso-butyl chloroformate. Also, acylation -15can be carried out with the free carboxylic acid with a condensing agent such as dicyclohexylcarbodiimide as described in U.S, Patent No, 3,218,318. The acylation is preferably carried out via the acid halide method or via the mixed anhydride method. The acylation via acyl halides can be carried out in an aqueous or non-aqueous solvent in the presence of a hydrogen halide acceptor such as sodium bicarbonate, a tertiary amine such as triethylamine or pyridine or an alkylene oxide such as propylene oxide or butylene oxide. The mixed anhydride method of acylation is carried out under anhydrous conditions in the presence of triethylamine.

II The carboxylic acids R'-C-OH employed in the synthesis of the compounds of the formula I are readily available either from commercial sources or via known preparative methods.

During the preparation of the compounds of formula X any reactive functional groups, such as the amino, hydroxy, or carboxy groups, are protected with a suitable 2q blocking group. Numerous carboxy, hydroxy, and aminoprotecting groups which are employed in the penicillin and cephalosporin art for the protection of such groups during the chemical reactions can be employed in the preparation of the compounds described herein. For example, the amino group can be protected with the t-butyloxycarbonyl group or the 2,2,2-trichloroethoxycarbonyl group; the hydroxy group can bo protected with the benzyloxycarbonyl group or a substituted benzyloxycarbonyl group, for example, 4nitrobenzyloxycarbonyl or the protecting group formed by -1646280 reacting the hydroxy group with methyl vinyl ether; and the substituents which are acidic, such as the carboxy, sulfo, or sulfamino groups, can be protected with a suitable carboxylic acid blocking group for example an ester such as benzyl, a substituted benzyl group, for example, 4-nitrobenzyl, 4-methoxybenzyl, or 2,4,6-trimethylbenzyl, the diphenylmethyl ester group, the trihaloethyl ester groups for example 2,2,2-trichloroethyl, or other suitable carboxylic acid blocking group. These blocking groups for the jQ above-defined functional groups are selected from those groups recognized as functional blocking groups which are readily cleaved following the reaction.

The azetidin-2-one compounds represented by the formula X wherein R is an acylamino group of the formula OH Z 0 II I ,·—κ 11 11 Ra-0-C-C-CHa-CHs-0—< >—C-C-NHI NH are prepared by acylating a 3B-aminoazetidin-2-one nucleus compound with the amino-protected and esterified 4-(3carboxy-3-aminopropoxy)phenylglyoxylic acid or the oxime or protected oxime thereof. This acid and the oxime or pro2q tected oxime are prepared by the following method.

An amino protected salt of D-methionine of the formula H II I M-O-C-C-CHs-CHa-S-CHa I NH -17for example, the salt wherein M is dicyclohexylammonium and R^5 is as previously defined herein, is converted to the trimethylsilyl ester and is alkylated on the sulfur atom with an alkyl Or benzyl iodide, for example methyl iodide, and the alkylsulfonium iodide of the formula OH ,II I t (CHa)sSI-O-C-C-CHa-CHs-S-CHn I I NH CHa is reacted in an inert solvent with potassium t-butoxide to form the cyclic amino-protected D-homoserine lactone of the formula II The lactone is hydrolyzed with an alkali metal hydroxide to the amino-protected D-homoserine alkali metal salt of the formula Η H . I 1 R -N-C-CHa-CHa-OH I CDOM' wherein M1 is sodium or potassium, and the latter is converted to an acid labile ester e.g., diphenylmethyl ester. The esterified D-homoserine is then coupled with 4-hydroxyphenylglyoxylic acid p-nitrobenzyl ester with a trialkyl or triaryl phosphine, preferably triphenylphosphine, and -1846280 diethyl azodicarboxylate to form the amino-protected diester of the formula OH 0 II I z··—·χ II ζ·—·χ Ra-0-C-C-CHa-CH2- 0-< > —C-COO-CHa—·( S—NOe I · X·—· NH The p-nitrobenzyl ester group is selectively de-esterified by reduction whereby the other ester Ra, which is selected from among the acid-labile ester groups, remains substantially intact. For example, the p-nitrobenzyl ester group is removed via reduction with sodium sulfide while the ester group Ra, which can be an acid sensitive group such as the Ιθ diphenylmethyl group, remains unaffected under the reduction conditions. The selective de-esterification product, the phenylglyoxylic acid, is represented by the formula OH 0 ll I .·—* II Ra-0-C-C-CH2-CHs:-0—/ S—C-COOH I >=· NH The amino-protected and esterified phenylglyoxylic acid is converted to an active ester which is used to acylate a 3p-aminoazetidin-2-one nucleus compound. After acylation the α-ketoacylamide intermediate is converter to the biologically active oxime. For example, 4—[3—(t— butyloxycarbamido)-3-(diphenylmethoxycarbonyl)propoxy]20 phenylglyoxylic acid is converted to the active ester formed with 1-hydroxybenzotriazole by using dicyclohexylcarbodiimide as condensing agent and the ester is coupled with 1-[a-(benzyloxycarbonyl)-4-benzyloxybenzyl]-30-amino-4a-1946280 acetoxyazetidin-2-one to provide 1-(a-(benzyloxycarbonyl)4-benzyloxybenzyl]-30-(4-(3-t-butyloxycarbamido)-3-(dipheny lmethoxycarbonyl) propoxy]phenylglyoxylamido-4txacetoxyazetidin-2-one represented by the following formula.

II H 11 1 DPM-O-C-C-CHz-CHe-O—/ \ I oZ N-H I +-BOC OOH II II I >—C-C-NOC-CHs LIx I ·= COO-Bz .o-O-Bz wherein DPM = diphenylmethyl; t-BOC = t-butyloxyoarbonyl; and Bz = benzyl.

The above α-ketoamide is then converted to the oxime derivative with hydroxylamine hydrochloride in the presence of a weak base such as sodium bicarbonate, and the t-BOC group, the DPM and benzyl groups removed to provide the antibiotic of the formula I as shown below.

H I HOOC-C-CHz-CHz-OI NHz H II I -C-C-N-f-f OH COOH OC-CHs -OH VI Alternatively, the nocardicin side chain can be synthesized by first forming the protected oxime of the 4-hydroxyphenylglyoxylic acid ester and then coupling the oxime ester with the amino-protected and and esterfied D-homoserine fragment followed by selective de-esterification of the glyoxylic acid ester. For example p-nitrobenzyl 4-hydroxyphenylglyoxylate is reacted with hydroxyl20 -2046280 amino hydrochloride and the oxime is reacted with potassium t-butoxidc Followed by p-methoxybenzyl bromide to form the O-(p-methoxybenzyl)oxime. The oxime Fragment is then coupled by the above described method with D-3-(t-butyloxy5 carbamido)-3-(diphenylmethoxycarbonyl)propanol (an amino protected and esterified D-homoserine) to form p-nitrobenzyl D-4-[3-(t-butyloxycarbamido)-3-(diphenylmethoxycarbonyl)propoxy]phenylglyoxylate 0-(p-methoxybenzyl)oxime represented by the formula DpMB OH N II I /·—*\ 11 DPM-O-C—C— GHs-CHa-O—·( S—C-C-O-pNB I χ·ζ=·ζ II N-H 0 I t-BOC wherein DPM = diphenylmethyl, t-BOC = t-butyloxycarbonyl, pMB = p-methoxybenzyl and pNB = p-nitrobenzyl.

The p-nitrobenzyl ester group is then removed by chemical reduction for example with zinc and acid or by electrolytic reduction to provide the free carboxylic acid for acylation of the 3R-amino nucleus.

Examples of the azetidin-2-ones of formula I wherein R is H 0 I II R' - - '-C—C-NHI NH I c=o I Y -2146280 <> are listed in the table below with reference to the foi lowing structural formula.

H II I -CH-C-N· N-Π c=o I Y II ,0-C-CHa VII COOH R Y phenyl 0 -n(ch3)c-nh-ch phenyl 0 -N(CH3)C-NH-CH 2-thienyl 0 -N(CH3)C-NH- 2-furyl 0 -N(CH3)C-NH-.CH. 4-hydroxy- 0 II phenyl -N(CH3)C-NH-CH. phenyl ^-H 5 phenyl Jl-SOzCHa a a' Η H 4-OH H Η H H 3-OH Η H 4-OH 3-Cl Η H 2-thienyl -NHC-CH=CHC,H_ 0 2-furyl -NHC-CHg II phenyl -NH-C-c>Hc 4-0H 3-CH3 Η H H 3-NH2 -22Examples of the antibiotic compounds of formula I wherein R is a qroup of the formula II R' '-C-C-NHII N I I Z are illustrated in the following table. Η II II R' · * '-C-C- II N 1 0-Z' 1 ,0-C-CHa w. cr ι ,; cooi /-χ s=.\ 1 a R Z' ' a a' phenyl H H H phenylCH3 4-OH H phenylCH3 H H phenyl H 4-OH H phenyl H 4-OH 3-C1 2-thienyl ch3 H H 2-thienyl H 4-OH H 2-thienyl CHg 4-Cl H 2-thienyl ch3 4-CHg H 2-thienyl ch3 4-nitro H 2-furyl H 4-OH H 2-furylCI13 4-OH H 2-furylCII3 11 11 2-furyl CUg 4-OH 3-C1 2-furyl II 4-Br H 2-furyl ch3 3-CH3 4-CHg 1/acetoxy -234628° The α-oximino and α-methoximino substituted azetidin-2-ones can have either the syn or anti configuration and their preparation as described above can lead to mixtures of both configurations. The preferred configura5 tion is the syn configuration.

Examples of the compounds of formula I wherein R is the group R''-CH2~C(0)-NH- are listed in the table below wherein reference is made to the following structural formula.

OH II II 1 O-C-CHa V 1 \=·\ COOH a R' * a a' phenyl Η H 4-hydroxyphenyl 4-OH H phenyl 4-OH H phenyl 3-OH H 2-thienyl Η H 2-thienyl 4-OH H 2-thienyl 4-OH 3-C1 2-furyl H . H 2-furyl 4-NH2 H thiazol-4-yl Η H IX -2446280 κ· isothiazol-5-yl 3-Br Η oxazol-5-yl Η Η oxazol-5-yl 4-CHg 3—CII^ oxazol-5-yl 4-OH Η ΙΗ-tetrazol-l-yl Η Η lH-tetrazol-1-yl isoxazol-4-yl 4-NH-CH Η 3-methyl-4-chloroisoxazol-5-yl ‘ 4-ΟΗ 3-(2-chlorophenyl)isoxazol-4-yl Η 3,4-dichloroisoxazol-5-yl 4-ΟΗ 3-chloro-4-methylisoxazol-5-yl Η 3,5-dimethylisoxazol-4-yl 4-OCH. Η Η 3-C1 Η 3-0CH.

Examples of the compounds of formula I wherein R is the acylamino group R'-S-CH2-C(0)-NH-are given in the table below with reference to the following structural formula.

H II I R'' '-S-CHz-C-N,OC-CHa COOH Χ·=ζ·\ -2546280 R' ' ' a a1 phenyl H H phenyl 4-OH H phenyl 4-Cl H 3,4-dichlorophenyl 4-OH 3-OCH 3,5-dichlorophenyl 4-OH 3-C1 3-methyl-4- hydroxyphenyl 4-OH H 4-pyridyl H H 4-pyridyl H 3-OH 4-pyridyl 3-C1 H 4-pyridyl 4-Br H 4-pyridyl 3-OC2H5 4-OH 2-thiazolyl 4-OH H 1,3,4-thiadia- zol-2-yl H H 1,3,4-thiadia- zolyl-2-yl 4-OH 3-C1 1,3,4-oxadiazol-2-yl H H 1,3,4-oxadia- zol-2-yl 3-CH3 4-CH3 Examples of the compounds represented by the formula X wherein R is a group of the formula H 0 I II R-C-C-NHI are listed below with reference to the following structural formula. -264 6 2 8 0 Η 0 Η II I II I 0-C-CH3 Q / fc—·: x· ι ·—»\ COOH a X. ! a' R Q phenylNH2 H H phenyl nh2 4-OH H phenyl nh2 4-OH 3-Cl phenyl nh2 4-Cl II 2-thienyl nh2 4-0Η H 2-furyl nh2 4-OH H 2-thienyl nh2 4-OCH3 3-CH3 phenyl OH 4-OH H phenyl COOH H H phenyl so3h 4-OH 3-OH 2-thienyl COOH H H 4-hydroxyphenyl NH2 H H 4-hydroxyphenyl COOH 4-OH 3-Cl 2-furyl so3h H 2-OCH3 3-chloro-4- hydroxyphenyl OH 4-OH H 2-thienyl OH 4-Cl H 2-thienyl -so3h 4-OC2H5 H 4-chlorophenyl OH 4-OH 3-CH3 The 3p-acylaminoazetidin-2-ones represented by formula I wherein R^, Ra, Rb and Z' are hydrogen, a and a' are other than protected hydroxy, protected amino or protected aminomethyl, and Q is other than a protected moiety, -27are useful antibiotics which inhibit the growth of pathogenic microorganisms. These compounds are resistant to inactivation by the β-lactamases and possess activity against the gramnegative bacteria which proliferate these enzymes, for example, proteus, pseudomonas, enterobacter sp., serratia and klebsiella.

The compounds are administered parenterally, for example, subcutaneously, intramuscularly or intravenously, preferably in the form of a pharmaceutically acceptable non-toxic salt.

The esterified, amino-protected, oxime-protected and hydroxy-protected azetidinones represented by the formula I useful as intermediates in the synthesis of the antibiotic compounds.

The azetidin-2-one antibiotics represented by the formula I have an acidic carboxylic acid group which forms salts with suitable bases. Pharmaceutically acceptable salts include the alkali metal salts such as the sodium, potassium, or lithium salt; the calcium salt; and salts formed with pharmaaeutically acceptable amines, for example, mono- and diethanol amine, procaine, cyclohexylamine, dicyclohexylamine, dibenzylamine, abietylamine, trimethylamine, or triethylamine. 3|3-Acylaminpazetidin-2-ones of the formula XI wherein Q is an amino group can form acid addition salts, for example, the hydrochloride or hydrobromide salts.

Likewise, when a phenyl group substituent a or a' and b or b' is amino, acid addition salts of the antibiotics can be prepared. -2846280 Further, it will be appreciated that the 30-amino and 30-acylamino which contain an α-amino substituent in the side chain (Q = NH2) can form intramolecular salts (zwitterions) when is hydrogen.

The 3|3-aminoazetidin-2-one nucleus compounds represented by the formula I when R is an amino group are useful intermediates in the preparation of the 3,3-acylaminoazetidin-2-one antibiotics. As described previously herein when the phenyl group of α-carboxybenzyl substituent in the 1-position of the azetidin-2-one ring is substituted with hydroxy or amino groups, such groups are preferably blocked with a suitable blocking group during synthesis for example, during N-acylation or N-deacylation. These nucleus compounds containing such blocked groups as well as esters of the nucleus compounds are also valuable intermediates. Examples of these nucleus compounds are listed below with reference to the following formula.

.O-C-CHs HeNXII a' COORi a a' ll H 11 H 4-OH H benzyl 4-benzyloxy H benzyl 4-Cl H DPM1 H 2-C1 pNB2 4-0-pNB 3-C1 -2946280 R1 a a' - — pNB 4-bonzyloxy 3-CH3 11 4-011 3-Br . pMB3 2-CH3O 4-CH30 H 2-Cl 6-Cl pNB 4-NH-BZ4 H benzyl 2-CH2NHBz . H 1/diphenylmethyl 2/p-nitrobenzyl 3/p-methoxybenzyl 4/benzyloxycarbonyl The carboxylic acid protecting groups represented by R^ in the formula I are carbon esters commonly used to temporarily protect or block the carboxylic acid function in other 0-lactam antibiotics such as the penicillins and cephalosporins. Examples of these ester groups include the haloalkyl groups such as the trichloroethyl and tribromoethyl groups; the benzyl and substituted benzyl groups such as p-nitrobenzyl, p-methoxybenzyl, 3,5-dimethoxybenzyl, 2,4,6-trimethylbenzyl; diphenylmethyl (benzhydryl), 4methoxydiphenylmethyl; or t-butyl. Methods for the removal of these ester groups are well known and are described in the literature.

As previously described herein, the 3-amino or 3-acylamino substituent R in the formula I has the 3configuration. The 4-acetoxy substituent group is provided in the α-configuration by the process described herein. -3046280 The α-carboxybenzyl or α-carboxy-substituted benzyl group substituted on the nitrogen atom of the azetidin2-one ring (1-position) can have either the D or L configuration and the D configuration is preferred. The process for preparing 3p-amino-4a-acetoxyazetidin-2-one nucleus described herein provides the preferred D-configuration when the phenylglycine employed in the process has the D-configuration.

Likewise the compounds of the formula I wherein R is the acylamino group H II I R''''-CH-C-NI Q can have either the D or L configuration. The described compounds having the D configuration are preferred.

Certain of the compounds of formula I are pre15 ferred over others. A preferred group is represented by the formula I when R is an acylamino group of the formula Z 0 ll 11 11 Ra-0-C-CH-CH2-CHz-0—/ S—C-C-NHI ·=· NH Preferred among these compounds are those wherein Ra and R^ are hydrogen, Z is the hydroxyimino group, a is 2q 4-hydroxy, and a1 is hydrogen. An especially preferred compound is 4a-acetoxynocardicin represented by the formula -3146280 II H -OH .O-C-CHa A preferred intermediate useful in the preparation of the above 4a-acetoxynocardicin is represented by the formula H DPM-O-C—C— CHs-CHs-O—S I o NHz H II I —C-C—N—< 11 I O-C-CHa COODPM •-0H XIV pMB Another preferred group of compounds of formula I are represented when R is benzoylamino, phenylacetylamino, or phenoxyacetylamino. These compounds are products of the process provided herein for the synthesis of the 4-acetoxy substituted azetidin-2-ones and can be used in the synthesis of the 3-amino-4-acetoxyazetidin-2-one nucleus as previously described.

The following examples are provided to further describe the compounds and process of this invention.

Preparation 1 Preparation of 2-benzoyl-3,3-dimethyl-7-oxo-a-(4-benzyloxyphonyl)-4-thia-2,6-diazabicyclo[3.2.0]heptane-6-acetic acid benzyl ester A slurry of 100 g. of L-cysteine in 2 1. of dry acetone was heated at the reflux temperature for about 17 hours. After the reaction mixture was allowed f joI to -32about 30°C. the unreacted cysteine was filtered and the reaction product, 2,2-dimethyl-4-thiazolidinecarboxylic acid, crystallized front the filtrate. Three crops of tho product were obtained via successive filtrations. The combined weight of product was 83 g.

To a suspension of 16 g. (100 mM) of the product in 300 ml. of dry acetone were added 21 ml. of propylene oxide. Next, 11.6 ml. (100 mM) of benzoyl chloride were added dropwise with vigorous stirring. The temperature of the reaction mixture slowly increased from about 25°C. to about 33°C. After an hour all of the thiazolidine had dissolved and the reaction solution began to cool. When the temperature had dropped to 30°C. the reaction solution was evaporated to yield a white solid residue. The solid was dissolved in acetone and was diluted with hexane to crystallize the product. The product, 3-benzoyl-2,2-dimethyl4-thiazolidinecarboxylic acid, was filtered and dried. The dried product weighed 18.7 g.

To a solution of 48 g. (181 mmole) of 3-benzoyl2,2-dimethyl-4-thiazolidinecarboxylic acid, prepared by the procedure described above in 1.5 1. of tetrahydrofuran were added 27.8 g. (181 mmole) of 1-hydroxybenzotriazole followed by 37.4 g. (181 mmole) of dicyclohexylcarbodiimide. The mixture was stirred for 30 minutes at room temperature. The reaction mixture developed into a thick slurry resulting from the precipitation of dicyclohexylurea. To the heavy slurry was added 63 g. (181 mmole) of benzyl D-4-benzyloxyphenylglycinate and the reaction mixture was stirred at room temperature for about 2 hours. The reaction mixture was -33filtered to remove the dicyclohexylurea, the filtrate evaporated under reduced pressure, and the residue was dissolved in ethyl acetate. The solution was washed successively with 5% hydrochloric acid, water, aqueous Sodium bicarbonate, and finally with water. The washed solution was dried, treated with carbon, and evaporated to dryness under reduced pressure to yield 107 g. (99% yield) of N[benzyl a-(D-4-beilzyloxyphenyl)acetate]-3-benzoyl-2,2dimethyl-4-thiazolidinecarboxamide.

The above thiazolidinecarboxamide ester (107 g.; 0.18 mole) was dissolved in 4 1. of benzene and 175 g. (0.72 mole) of benzoyl peroxide were added to the solution. The solution was then heated at the reflux temperature for 4.5 hours and thereafter was cooled to room temperature. The reaction mixture was poured over a column packed with silica gel and the column was eluted with benzene. Excess benzoyl peroxide passed off the column initially and on further elution with benzene, the product was collected. The eluate was evaporated under reduced pressure to provide the pro20 duct, N-[benzyl a-(D-4-benzyloxyphenyl)acetate]-3-benzoyl2,2-dimethyl-4-thiazolidinecarboxamide-5a-benzoate, as an oil. The product was obtained crystalline from diethyl ether.

The above product is represented by the following . π c structural formula Λ/ 11 /\ Xl.

CHs II o-c-·; o=c I .·—·. .·—·. ΗΝ-ζΉ-·ζ )»-0CHz-»( )· COOCHb-·^ S •rr»z NMR (T60, CDClj): 2.16 (s, 2CH3), 5.08 and 5.16 (2s, 2CH2) , .13 (s, CH), 5.54 (d, CH), 6.54 (s, CH) and 6.83-8.16 (m, aromatic H and NH) delta.

A solution of 25.5 g. (35.8 mmole) of the thiazolidine-4-carboxamide 5a-benzoate in 1 1. of dry methylene chloride was cooled to a temperature of 0°C. and hydrogen chloride was bubbled through the cold solution for about 2 hours. After this time, a thin layer chromatogram developed with benzene:ethyl acetate, 7:3, v.v, showed complete reaction. The methylene chloride was evaporated under reduced pressure providing the product as a foam. The foam was dissolved in ethyl acetate and the solution was washed with a dilute aqueous solution of sodium bicarbonate and with brine, and after washing was dried over magnesium sulfate, treated with carbon, and evaporated to dryness under reduced pressure. The product, N-[benzyl a-(D-4benzyloxyphenyl)acetate]-3-benzoyl-2,2-dimethyl-5a-chloro4-thiazolidinecarboxamide, represented by the following formula was obtained as 22.4 g. of white foam. -3546280 11 / \ •'HLl ••Cl o=c I .·—·. .·—·.

HN-QH-·/ /«-0CH2-»< S 1Z > » Λ-·.

COOCHs-βζ /· 'o~© NMR (T60, CDClg): 2.12 (s, CHg), 2.26 (s, CHg), 5.08 and 5.16 (2s, 2CH2). 5.16 (s, CH) , 5.44 (d, CH), 5.83 (s, CH) and 6.08-7.5 (m, 20H, aromatic H and NH) delta.

To a solution of 22.4 g. (35.8 mmole) of the 5achloro-4-thiazolidinecarboxamide in 800 ml. of methylene chloride and 200 ml. of dimethylformamide were added 1.72 g. of sodium hydride (50 percent in oil, 35.8 mmole). The reaction mixture was stirred at room temperature for approximately 50 minutes after which time TLC (benzene:ethyl acetate, 7:3) showed the reaction was complete. Two milliliters of acetic acid were added to the reaction mixture to destroy any excess sodium hydride, and the reaction mixture was poured into 5 percent hydrochloric acid. The organic phase was separated and was washed with 5 percent hydrochloric acid and with water before drying over magnesium sulfate. The dried extract was treated with carbon, filtered, and evaporated to dryness under reduced pressure.

The residue was dissolved in about 30 ml. ethyl acetate. On standing, 10.1 g. (crop 1) of product, 2-benzoyl-3,3dimcthyl-7-οχο-α-(4-benzyloxyphenyl)-4-thia-2,6-diaza-364 6 2 8 0 bicyclo[3.2.0]heptane-6-acetic acid benzyl ester, crystallized. The crystals were filtered and the filtrate was treated with petroleum ether to the cloud point. On standing and with agitation, 5.5 g. (crop 2) of additional product crystallized. The second crop material was filtered and the filtrate was evaporated to dryness to yield further product as a foam. The foam was treated with a mixture of ethyl acetate and ethyl alcohol which afforded 2.2 g. of additional crystalline product (crop 3).

An analysis of the nuclear magnetic resonance spectrum (T-60) of the above crops demonstrated that crop 1 was·the D isomer of the cyclized product represented by the formula shown below, crop 2 was the L isomer, while crop 3 was a mixture of the two isomers.

,·—·. II (L) HsC ,CHs 0 V c-/\ A-C—A ^«-O-CHa- \χ=·ζ \=·ζ ,·—·.

*COOCHz-»( NMR (T60, CDClg): 1.70 (s, CHg), 1.91 (s, CHg), 5.08 and 5.16 (2s, 2CH2) , 5.45 (s, CH), 5.52 (m, 2CH), and 6.83-7.67 (m, 19H, aromatic II) delta.

The above thiazolidine azetidinone was also prepared from the 5a-chlorothiazolidine carboxamide and the base diazabicyclo[5.4.0]undec-5-ene(DBU) in the following manner. -37A solution of 1.01 g. (1.6 mmole) of the 5achloro-4-thiazolidinecarboxamide having the D-configuration in 50 ml. of methylene chloride was cooled to a temperature of about 0°C. To the cold solution was added 0.243 g. (1.6 mmole) of DBU. The reaction mixture was stirred for 2 hours at 0°C. and then was washed with 5 percent hydrochloric acid and with brine and was then dried over magnesium sulfate.

The solution was evaporated to yield a crude reaction product mixture. The mixture was crystallized from benzene/ petroleum ether and the crystals filtered. The infrared spectrum of the product showed an absorption peak at 1775 cm for the β-lactam carbonyl, while the nuclear magnetic resonance spectrum and circular dichromism showed the material to be optically pure.

Example 1 Preparation of 1-[a-(benzyloxycarbonyl)-4-benzyloxybenzyl]3|3-benzamido-4a-acetoxyazetidin-2-one.

A slurry of 300 mg (0.505 mmole) 2-benzoyl-3,3dimethyl-7-οχο-α-(4-benzyloxyphenyl)-4-thia-2,6-diazabi20 cyclo[3.2.0]heptane-6-acetic acid benzyl ester in 25 ml. of acetic acid was stirred and treated with 240 mg. (0.75 mmole) of mercuric acetate. The reaction mixture was heated on the steam bath for 10 minutes, and an additional 100 mg. of mercuric acetate was added and heating was continued for minutes. The reaction mixture was filtered to remove the .insoluble mercurous acetate and was then evaporated to dryness. The residue was dissolved in ethyl acetate and the solution was washed with a dilute aqueous solution of sodium bicarbonate and with brine, was dried and then evaporated to -3846280 dryness to yield 1-[a-(benzyloxycarbonyl)-4-benzyloxybenzyl] -3- (N-propenylbenzamido)-4-a~acetoxyazetidinone-2 represented by the following formula.

H * * · /*—*\ cooche—·ζ S The product was dissolved in 50 ml. of tetrahydrofuran and 5 ml. of 5 percent hydrochloric acid were added. After stirring for 15 minutes at room temperature the solution was evaporated to dryness under reduced pressure and the residue was dissolved in ethyl acetate. The ethyl acetate solution was washed with a dilute aqueous solution of sodium bicarbonate, with water, and was dried and evaporated to dryness. The residue was chromatographed on a preparative silica gel thin layer plate using benzene: ethyl acetate, 7:3, v:v, for development to obtain 144 mg. of the hydrolysis product 1-[a-(benzyloxycarbonyl)-4benzyloxybenzyl]-3B-benzamido-4-a-acetoxyazetidinone-2.

Example 2 By following the procedures described by Example 1 1-[a-(benzyloxycarbonyl)-4-benzyloxybenzyl]-38-phenoxy2q acetamido-4a-acetoxyazetidin-2-one is prepared with the benzyl ester of 2-phenoxyacetyl-3,3-dimethyl-7-oxo-a(4-benzyloxyphenyl)-4-thia-2,6-diazabicyclo[3.2.0]heptane6-acetic acid. -3946280 Example 3 Preparation of 1-[a-(benzyloxycarbonyl)-4-benzyloxybenzyl]3 0-amino-4a-acetoxyazetidin-2-one.

To a solution of 250 mg. (0.432 mmole) of 15 [a-(benzyloxycarbonyl)-4-benzyloxybenzyl]-30-benzamido4-a-acetoxyazetidinone-2 prepared as described in the foregoing Example 1 in 50 ml. of dry benzene were added 132 mg. (0.64 mmole) of phosphorous pentachloride and 50 mg. (0.64 mmole) of pyridine. The mixture was heated to a Ιθ temperature of about 65°C. for 2 hours with stirring. A thin layer chromatogram was then run on the reaction mixture and demonstrated the conversion of the starting material to the corresponding imido chloride.

The reaction mixture was evaporated under reduced pressure and 50 ml. of dry methyl alcohol were added to the residue. The methyl alcohol solution was stirred at room temperature for about 30 minutes. TLC of the solution showed a new spot.

The solution was evaporated under reduced pressure 2q and 20 ml. of water and 20 ml. of tetrahydrofuran were added to the residue and the resultant solution was stirred at room temperature for about 20 minutes. The tetrahydrofuran was evaporated from the solution and the aqueous concentrate was slurried with ethyl acetate. The pH of the slurry was adjusted to pH 7 and the ethyl acetate layer was separated.

The ethyl acetate layer was dried and then evaporated under reduced pressure to afford 210 mg. of a reduction product mixture. The nuclear magnetic resonance spectrum (T-60) of the product mixture showed it contained approximately 60 -404628ο percent of the desired N-deacylation product, 1-[a-(benzyloxycarbonyl) -4-benzyloxybenzyl]-3-.5-amino-4-a-acetoxyazetidinone-2 represented by the following structural formula.

HaN oAc ’cOOCHz—·/ /> ·“· The crude product was purified via preparative thin layer chromatography on silica gel thick layer plates to yield 62 mg. of the product and 60 mg. of recovered starting material.

Example 4 Preparation of 1-[a-(carboxy)-4-hydroxybenzyl]-3β-(Dmandelamido)-4a-acetoxyazetidin-2-one.

To a solution of 1-[a-(p-nitrobenzyloxycarbonyl)4-benzyloxybenzyl]-3B-amino-4a-acetoxyazetidin-2-one in tetrahydrofuran maintained at 0-5°C. are added pyridine and 0-formyl mandeloyl chloride. The mixture is stirred in the cold for about 2 hours and is then evaporated. Water is added to the residue and the acylation product is extracted with ethyl acetate. The extract is washed with water, dilute acid, and again with water and is dried and then evaporated to yield the esterified N-acylation product, 1-[a-(p-nitrobenzyloxycarbonyl)-4-benzyloxybenzyl]-3β(O-formylmandelamido)-4a-acetoxyazetidin-2-one. The ester is de-esterified with zinc and acetic acid during which the 4-benzyloxy group is removed to provide the title compound. -4146 28 0 Example 5 Preparation of 1-[a-(carboxy)-4-hydroxybenzyl]-3f)-12-[4(3-carboxy-3-aminopropoxy)phenyl]-2-hydroximinoacetamido]4a-acetoxyazetidin-2-one.

To a solution of 32 mg. of 1-[a-(benzyloxycarbonyl) -4-benzyloxybenzyl]-3(3-amino-4a-acetoxyazetidin2-one in about 5 ml. of dry methylene chloride were added 36 mg. of 4-(3-diphenylmethoxycarbonyl-3-t-butyloxycarbamidopropoxy)phenylglyoxylic acid. The mixture was stirred at room temperature under nitrogen and 14 mg. of dicyclohexylcarbodiimide were added. The solution immediately turned a dark yellow. After 10 minutes the solution became light yellow and dicyclohexylurea precipitated. A thin layer chromatogram of the mixture run on silica gel plates with benzene:ethyl acetate, 7:3, v:v, showed complete reaction. The reaction mixture was filtered and the filtrate was evaporated to dryness.

The acylation product was purified on preparative thick layer plates (silica gel) to yield 41 mg. of the purified intermediate product.

The product was reacted with hydroxylamine hydrochloride in aqueous tetrahydrofuran containing pyridine to form the hydroximino derivative. The oxime was reacted with trifluoroacetic acid in anisole to cleave both the t-BOC amino-protecting group and the diphenylmethyl ester group of the side chain. After treatment with the acid, the reaction mixture was evaporated to dryness and the residue was vigorously triturated with diethyl ether. The insoluble product, 1-[a-(benzyloxycarbonyl)-4-benzyloxybenzyl]-3β-424 6 2 8 0 V [2-[4-(3-carboxy-3-aminopropoxy)phenyl]-2-hydroxyiminoacetamido]-4a-acetoxyazetidin-2-one trifluoroacetate salt, was filtered and dried.

The salt was dissolved in dry methylene chloride and was treated with a solution of excess aluminum chloride and anisole in nitromethane to effect the removal of both benzyl ester groups. The reaction mixture was quenched with water and the pH adjusted to about 8.0 with sodium bicarbonate. The solution was washed with ethyl acetate and was then chromatographed over Sephadex. The title compound was obtained as the disodium salt by evaporation of the eluate.

The course of the debenzylation reaction is followed by thin layer chromatography over silica gel using acetic acid:acetone, 4:1, v:v, for development.

Example 6 Preparation of l-[a-(diphenylmethoxycarbonyl)-4-hydroxybenzyl]-33-amino-4a-acetoxyazetidin-2-one.

A solution of 4 g. of 2-benzoyl-3,3-dimethyli v 7-oxo-a- (4-hydroxyphenyl) -4-thia-2, 6-diazab'i cyclo [3.2.0] 2o heptane-6-acetic acid and 5 g. of diphenyldiazomethane in 500 ml. of dry tetrahydrofuran was stirred at room temperature for about 18 hours. The reaction mixture was evaporated under reduced pressure to dryness and the residue was dissolved in ethyl acetate. The diphenylmethyl ester product, 2-benzoyl-3,3-dimethyl-7-oxo-a-(4-hydroxyphenyl)t / 4-thia-2,6-diazab'i cyclo[3.2.0]heptane-6-acetic acid diphenylmethyl ester, crystallized from solution. 3.5 Grams of the diphenylmethyl ester were obtained. -4346280 To a suspension of 1 g. of the diphenylmethyl ester in approximately 100 ml. of acetic acid were added with stirring 1 g. of mercuric acetate. The reaction mixture was heated on the steam bath for approximately 10 minutes with continued stirring. The reaction mixture was filtered to remove the insolubles and was evaporated under reduced pressure to dryness. The reaction product mixture obtained as a residue was dissolved in ethyl acetate and the solution was washed with a dilute aqueous solution of sodium bicarbonate and with brine and was then dried and evaporated to dryness to yield 1.1 g. of 1-[a-(diphenylmethoxycarbonyl) -4-hydroxybenzyl]-3-(N-propenylbenzamido)-4a-acetoxyazetidinone-2.

The propenyl 4a-acetoxyazetidin-2-one diphenylmethyl ester, 650 mg. was dissolved in 50 ml. of water and 50 ml. of tetrahydrofuran and 650 mg. of mercuric acetate were added. The reaction mixture was stirred at about room temperature for approximately 1 hour. The reaction mixture was evaporated to dryness under reduced pressure and the residue containing the hydrolysis product was dissolved in ethyl acetate. The ethyl acetate solution was washed with a dilute aqueous solution of sodium bicarbonate, water, and was then dried and evaporated to dryness. The nuclear magnetic resonance spectrum (T60) showed that complete hydrolysis of the N-propenyl group had taken place. The product, 600 mg., 1-[a-(diphenylmethoxycarbonyl)-4-hydroxybenzyl] -3P-benzamido-4a-acetoxyazetidinone-2 was used without further purification as described hereinafter. -4446280 To a solution of 510 mg. of the 4a-acetoxyazetidinone-2-diphenylmethyl ester prepared as described above in 40 ml. of dry tetrahydrofuran were added 2 ml. of dihydropyran and a small catalytic amount of p-toluenesulfonic acid. The reaction mixture was stirred at about room temperature for approximately 17 hours. A silica gel thin layer chromatogram showed the presence of starting material and the desired product, the tetrahydropyranyl ether formed with the 4-hydroxybenzyl group. With continued stirring approximately 0.5 g. of sodium carbonate were added to the reaction mixture. After stirring for 15 minutes the solvent tetrahydrofuran was evaporated and the residue was dissolved in ethyl acetate. The ethyl acetate solution was washed with sodium bicarbonate and with water and was then dried and evaporated to dryness. The starting material and product contained in the residue were separated on a silica gel chromatographic plate employing 7:3, toluene:ethyl acetate, v:v, for elution. There were obtained 280 mg. of the product, 1-[a-(diphenylmethoxycarbonyl)-4-tetrahydropyranyloxybenzyl]-3|3-benzamido-4a-acetoxyazetidinone-2 and 178 mg. of recovered starting material.

To a solution of 78.5 mg. (0.38 mmole) of phosphorus pentachloride and 29.9 mg. (0.38 mmole) of pyridine in approximately 20 ml. of dry methylene chloride were added with stirring at room temperature under nitrogen 168 mg. (0.26 mmole) of the 4a-acetoxyazetidin-2-one tetrahydropyranyl ether diphenylmethyl ester. The reaction mixture was stirred at room temperature under nitrogen and peri-4546230 odically an aliquot was withdrawn from the reaction mixture and chromatographed on thin layer chromatography plates using benzene:ethyl acetate, 7:3 for elution. After approximately 1 hour the TLC showed only a trace of starting material and a new spot corresponding to the imino chloride.

The methylene chloride was evaporated and 30 ml. of dry methyl alcohol were added to the concentrate. The methyl alcohol solution was stirred for approximately 2 hours at about room temperature. Thereafter, the methanol was 1q evaporated and 20 ml. of water and 20 ml. of tetrahydrofuran were added to the residue. The aqueous solution was stirred for approximately 1 hour at about room temperature and thereafter the solution was evaporated to remove the tetrahydrofuran. The aqueous concentrate was extracted with ethyl acetate and the extract was dried and evaporated to dryness. The product obtained as a crude residue was purified via chromatography over silica gel to yield 81 mg. of 1-[a-(diphenylmethoxycarbonyl)-4-hydroxybenzyl]-3pamino-4a-acetoxyazetidin-2-one. 2q Example 7 Preparation of 4a-acetoxynocardioin.

To a solution of 300 mg. (0.65 mmole) of the 4a-acetoxyazetidin-2-one nucleus diphenylmethyl ester prepared as described in the preceding example and 435 mg. (0.65 mmole) of 4-[3-(diphenylmethoxycarbonyl)-3-(tbutyloxyoarbamido)propoxy]phenylglyoxylic acid 0-(4methoxybenzyl)oxime in approximately 25 ml. of dry methylene chloride maintained at about room temperature under nitrogen were added 135 mg. (0.65 mmole) of dicyclohexylcarbodiimide. -4646280 The reaction mixture was stirred at approximately room temperature under nitrogen for about 2 hours. The reaction mixture was filtered and the filtrate was evaporated to dryness. The residue was chromatographed on a preparative silica gel chromatographic plate employing toluene:ethyl acetate, 1:1, v:v for elution to obtain 391 mg. of the acylated product, the t-butyloxycarbonyl protected amino, bis-dibenzhydryl ester protected and 4-methoxybenzyl protected oxime derivative of 4o-acetoxynocardicin represented by the formula below. The NMR of the product (T60) showed a trace impurity. The product was further purified in the same chromatographic system affording 332 mg. of the purified product.

II The protected bis-diphenylmethylester of 4aacetoxynocardicin of the above formula was treated with 12 ml. of trifluoroacetic acid containing 24 drops of anisole at approximately room temperature for 3 minutes. The reaction mixture was evaporated to dryness and the residue was vigorously triturated with diethyl ether to yield 157 mg. of 4a-acetoxynocardicin trifluoroacetate salt.

NMR: DMSO(Dg), D20 (Trimethylsilane reference, 1.95 (s, -C(O)CI13), 2.31 (t, CH2) , 4.15 (t, and d, -CH-CH2), 4.74 (d, -CH-), 5.20 (s, -CH-), 5.88 (d, -CH-) and 6.66-7.52 (aromatic H) delta.

Claims (45)

1. CLAIM S:1. A 4a-acetoxyazetidin-2-one compound of the formula R0 II /O-C-CHa wherein a and a' independently are hydrogen, halogen, hydroxy, protected hydroxy, C^-C^ alkyl, C-^-C^ alkoxy, amino, protected amino, aminomethyl, or protected aminomethyl ; R is amino or ah acylamino group; and R^ is hydrogen or a carboxylic acid protecting group; and when R^ is hydrogen the pharmaceutically acceptable nontoxic salts thereof.

2. A compound of claim 1 wherein R is an acylamino group of the formula 0 H ll I R’-C-Nwherein R' is C^-C^ alkyl, cyanomethyl, bromomethyl, chloromethyl, phenyl, or a group of the formula 0 Z ll 11 R a -0-C“CH-CH2-CHs-0-»(' S-CNH R b wherein R a is hydrogen, benzyl, diphenylmethyl or 42o methoxybenzyl; R^ is hydrogen or an amino-protecting group of the formula -4846280 Ο ιι R c -O~Cwherein R C is t-butyl, 2,2,2-trichloroethyl, benzyl, 4-nitrobenzyl, cyclopentyl, or cyclohexyl; Z is =0 or =N-OZ', wherein Z' is hydrogen, acetyl, chloroacetyl, triphenylmethyl or p-methoxybenzyl; or R' is a group of the formula R''-CH 2 ~ wherein R' 1 is a phenyl group of the formula wherein b and b' independently are hydrogen, halogen, hydroxy, C 1 ~C 4 alkyl, C 1 ~C 4 alkoxy, amino or aminomethyl; or R' 1 is thienyl, furyl, thiazolyl, oxazolyl, isothiazolyl, tetrazolyl, or an isoxazolyl group of the formula wherein d is hydrogen, methyl, or a group of the formula wherein b and b' have the same meanings defined above, and d' is hydrogen, methyl, or chloro; or R' is a phenoxymethyl group of the formula -4946280 ,®—0CHs“ h/ wherein b and b' have the same meanings as defined above; or R' is a group of the formula R'’'-S-CH^wherein R 111 is a group of the formula wherein b and b* are as defined above, 4-pyridyl, thiazolyl, thiadiazolyl, or oxadiazolyl; or R' is a group of the formula H I R-CI wherein R'*' 1 is a phenyl group of the formula >«=./· wherein b and b' are as defined above, 15 thienyl or furyl; and Q is amino, hydroxy, carboxy, -SO^H, or -NH-SO^II, or any of these groups in protected form; or R' is a group of tho formula -5046280 . R'''C— II Ν I I Z wherein R*’ has the same meanings as defined above and Z is hydrogen, acetyl or methyl; or R' is a group of the formula H 5 1 R-CI N-H I C=0 I Y wherein R''' 1 is as defined above; and Y is a dimethylureido group of the formula CHa 0 H . I II I - N - C - N - CHa , an imidazolidin-2-one group II wherein Y’ is hydrogen, C^-C, alkyl, C 2 ~C^ alkanoyl, or methanesulfonyi; or an N-methylacyl group of the formula CH3 0 I II -N -C-Y 15 wherein Y' 1 is C^-C, alkyl, or a group of the formula -5146280 — (CH = CH); --Z\ wherein n = 0 or 1 and a hydrogen, nitro, or chloro.

3. A compound of Claim 1 or 2 wherein when R is an acylamino group it has the formula 0 H R· 1 ·- C - N — as defined in Claim 2 provided that when Z is = N OZ^, Z^ is hydrogen, and when R a is group of formula H tl tt I R - C — Q is amino, hydroxy, carboxy, -SOgH or -NH-SOgH. 10

4. A ccmpound of claim 1, 2 or 3 wherein R 1 is a group of the formula a R -0-C-CH-CH_-CH_-0 NH wherein R' is a R , R° and Z are as defined in

5. A compound of claim 4

6. A compound of claim 4

7. A compound of claim 1 group of the formula claim 2. wherein Z is =0. wherein Z is =N-OZ , 2 or 3 wherein R - CH Q wherein R is as defined above and 2o Q is amino, hydroxy, or carboxy.

8. A compound of claim 1, 2 or 3 wherein R' is phenyl, benzyl, or phenoxymethyl.

9. A compound of any of claims 1 to 3 or 8 wherein R 1 is phenyl. 25

10. A conpound of claim 1 or 2 or. 3 wherein R' is a group of the formula R - CH 2 wherein R is as defined in claim 2.

11. A compound of claim 10wherein R'' is phenyl, 2-thienyl, 2-furyl, or 1-tetrazolyl.

12. A compound of claim 1, 2 or 3 wherein R' is a group of the formula y-\. b' •Γ. \·—O-CHswherein b and b' are as defined in claim 2.

13. A compound of claim 1, 2 or 3 wherein R' is a group of the formula R' ''-S-CH 2 wherein R''' is as defined in claim 2.

14. A compound of claim 1, 2 or 3 wherein R' is a group of the formula • r> *·‘-CII N I I Z and R'''' is phenyl, 2-furyl, or 2-thienyl? and Z 1 ' is as defined in claim 2,

15. A compound of claim 1 ,· 2 or 3 wherein R' is a group of the formula R '-CHI N-H I C = 0 I Y wherein R 11 ' 1 and Y are as defined in claim 2. -534 6 2 8 0

16. Λ compound of claim 15 vzherein Y is a dimethylurcido group of the Eormula CHa 0 H I II I - N - C - N - CHa

17. A compound of claim 15 wherein Y is a group of the formula II o wherein Y' is as defined in claim 2.

18. A compound of claim 15 wherein Y is an Nmethylacyl group of the formula CHa 0 I ll - N- C-Y wherein Y' 1 is as defined in claim 2.

19. The compound of claim 1 wherein R is amino.

20. 1-[a-(Benzyloxycarbonyl)-4-benzyloxybenzyl]3f5-benzamido-4a-acetoxyazetidin-2-one.

21. « I - [a-(Benzyloxycarbonyl)-4-benzyloxybenzyl]3f3-phenoxyacetamido-4-a-acetoxyazetidin-2-one.

22. 1[a - (Benzyloxycarbonyl)-4-benzyloxybenzyl]30-amino-4a-acetoxyazetidin-2-one.

23. 1-[a-(Carboxy)-4-hydroxybenzyl]-33-(Dmandelamido)-4a-acetoxyazetidinon-2-one.

24. 1-[α-Benzyloxycarbonyl)-4-benzyloxybenzyl]3(5-I 2-[4-(3-diphenylmethoxycarbonyl-3-t-butyloxycarbamidopropoxy)phenyl J glyoxylamido]-4a-acetoxyazetidin-2-one. -544628 0

25. 1-[a-(Diphenylmethoxycarbonyl)-4-hydroxybenzyl] -3|3-benzamido-4a-acetoxyazetidin-2-one.

26. I - [a-(Diphenylmethoxycarbonyl)-4-hydroxybenzyl]-3/3-amino-4a-acetoxyazetidin-2-one.

27. 1-[a-(Carboxy)-4-hydroxybenzyl]-3 3-[2-[4(3-carboxy-3-aminopropoxy)pheny j]-2-hydroxy iminoacetamido] 4a-acetoxyazetidin-2-one.

28. 1-[α-Diphenylmethoxycarbonyl)-4-hydroxy10 benzyl] -3β- [2- [4-(3-diphenylmethoxycarbonyl-3-t-butyloxycarbamidopropoxy)phenyl]-2-(4-methoxybenzyloxy)iminoacetamido]-4a-acetoxyazetidin-2-one.

29. A process for preparing a 4a-acetoxyazetidin2-one compound of 'formula I as defined in any one of claims 1 to 28 which comprises heating a thiazolidine azetidinone compound of formula II coor-l -554 6 2 8 0 wherein Ra is C-^-C-j alkyl, phenyl, benzyl or phenoxymethyl; and R^, a and a' are as defined above; of acetic acid to form amide of the formula III wherein Ra, R^, a and a’ are as defined above; hydrolyzing the 4a-acetoxyazetidin-2-one amide to form a 4a-acetoxyazetidin-2-one of the formula with mercuric acetate m the presence a N-propenyl 4a-acetoxyazetidin-2-one CHa I 0 C=CHz II I Ra-C—N· 0 II Ra-C-NH—·' yO-C-CHa nur*· II ,0-C-CHa LL? /“X* Λ ι x=.<, COOR-ι a IV wherein Ra, R^, a and a* are as defined above; if desired cleaving by conventional methods·the 3-position acyl group to provide a compound of formula I wherein R is amino; if desired reacylating the 3-amino-4a-azetidin-2one compound so obtained by conventional methods; and optionally removing the carboxy, hydroxy or amino protecting groups.

30. The process of claim 29 wherein the thiazolidine azetidinone is heated at a temperature Of from 25° to 75°C.

31. The process of claim 29 or 3Θ. wherein the thiazolidine azetidinone is heated with between 1.5 and 2.0 moles of mercuric acetate per mole of said thiazolidine azetidinone. -5646280

32. The process of any of claims 29 to 31 wherein the N-propenyl 4a-acetoxyazetidin-2-one amide is hydrolyzed with mercuric acetate in an aqueous solvent.

33. The process of claim 29 for preparing l-[a(benzyloxycarbonyl)-4-benzyloxybenzyl]-33-benzamido-4aacetoxyazetidin-2-one which comprises heating 2-benzoylt 3,3-dimethyl-7-oxo-a-(4-benzyloxyphenyl)-4-thia-2,6diazabicyclo[3.2.0]heptane-6-acetic acid benzyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous hydrochloric acid.

34. The process of claim 29 for preparing l-[a(benzyloxycarbonyl)-4-benzyloxybenzyl]-30-phenoxyacetamido4a-acetoxyazetidin-2-one which comprises heating 2-phenoxyacetyl-3,3-dimethyl-7-oxo-a-(4-benzyloxyphenyl)-4-thia2,6-diazabicyclo[3.2.0]heptane-6-acetic acid benzyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous hydrochloric acid.

35. The process of claim 29 for preparing l-[a(benzyloxycarbonyl)-4-benzyloxybenzyl]-33-amino-4a-acetoxyazetidin-2-one which comprises heating 2-benzoyl-3,3dimethyl-7-οχο-α-(4-benzyloxyphenyl)-4-thia-2,6-diazabicyclo[3.2.0]heptane-6-acetic acid benzyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous hydrochloric acid; and reacting the resulting 30-benzamido-4a-acetoxyazetidin-2-one with phosphorous pentachloride in pyridine followed by hydrolysis.

36. The process of claim 29 for preparing l-[a(carboxy)-4-hydroxybenzyl]-30-(D-mandelamido)-4a-aoetoxyazetidin-2-one which comprises heating 2-benzoyl-3,3-5746280 dimethyl-7-οχο-α-(4-benzyloxyphenyl)-4-thia-2,6-diazabicyclo [3.2.0]heptane-6-acetic acid p-nitrobenzyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous hydrochloric acid; reacting the resulting 3p-benzamido-4a-acetoxyazetidin-2-one with phosphorous pentachloride in pyridine followed by hydrolysis reacting the 33-amino-4cc-acetoxyazetidin-2-one so obtained with 0-formyl mandeloyl chloride; and removing the carboxy and hydroxy protecting groups.

37. The process of claim 29 for preparing 1-[a(benzyloxycarbonyl)-4-benzyloxybenzyl]-3(3-[2-[4-(3-diphenylmethoxycarbonyl-3-t-butyloxycarbamidopropoxy)phenyl]glyoxylamido]-4a-acetoxyazetidin-2-one which comprises heating 2-benzoyl-3,3-dimethyl-7-oxo-a-(4-benzyloxyphenyl)4-thia-2,6-diazabicyclo[3.2.0]heptane-6-acetic acid benzyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous hydrochloric acid; reacting the resulting 38-benzamido-4a-acetoxyazetidin-2one with phosphorous pentachloride followed by hydrolysis; and reacting the 3[3-amino-4a-acetoxyazetidinon-2-one so obtained With 4-(3-diphenylmethoxycarbonyl-3-t-butyloxycarbamidopropoxy)phenylglyoxylic acid.

38. The process of claim 29 for preparing l-[a(diphenylmethoxycarbonyl)-4-hydroxybenzyl]-3|3-benzamido4a-acetoxyazetidin-2-one which comprises heating 2-benzoyl3,3-dimethyl-7-oxo-a-(4-hydroxyphenyl)-4-thia-2,6-diazabicyclo [3.2.0 ]heptane-6-acetic acid diphenylmethyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous mercuric acetate. -5846280

39. The process of claim 29 for preparing l-[a(diphenylmethoxycarbonyl)-4-hydroxybenzyl]-3!3-amino-4aacetoxyazetidin-2-one which comprises heating 2-benzoyl3,3-dimethyl-7-oxo-a-(4-hydroxyphenyl)-4-thia-2,6-diazabicyclo[3.2.0]heptane-6-acetic acid diphenylmethyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous mercuric acetate; and reacting the resulting 30-benzamido-4a~acetoxyazetidin-2-one with phosphorous pentachloride in pyridine followed by hydrolysis.

40. The process of claim 29 for preparing l-[a(carboxy)-4-hydroxybenzyl]-30-[2-[4-(3-carboxy-3-aminopropoxy) phenyl]-2-hydroxyiminoacetamido]-4a-acetoxyazetidin2-one which comprises heating 2-benzoyl-3,3-dimethyl-7oxo-a-(4-hydroxyphenyl)-4-thia-2,6-diazabicyclo[3.2.0]heptane-6-acetic acid diphenylmethyl ester with mercuric acetate in the presence of acetic acid; followed by hydrolysis with aqueous mercuric acetate; reacting the resulting 30-benzamido-4a-acetoxyazetidin-2-one with phosphorous pentachloride in pyridine followed by hydrolysis; reacting the 30-amino-4a-acetoxyazetidin-2-one so obtained with 4-(3-diphenylmethoxycarbonyl-3-(t-butyloxycarbamido)propoxy)phenylglyoxylic acid 0-(4-methoxybenzyl)oxime; and removing the carboxy, hydroxy and amino protecting groups. V,

41. A process as claimed in claim 29 substantially as hereinbefore described with particular reference to any one of Examples 1 to 7.

42. A compound as claimed in claim 1 substantially 5 as hereinbefore described with particular reference to any one of. Examples 1 to 7.

43. A ccmpound according to Claim 1 whenever prepared by a process according to any one of Claims 29 to 41.

44. A pharmaceutical formulation comprising a ccmpound as defined in any one of Claims 1 to 28, η ν Ί 42 and 43 wherein.Rp R , R -and 2- are hydrogen, a and a 1 are other than protected hydroxy, protected amino or protected aminomethyl and Q is other 'than a protected moiety; or a . jfaOTiacaitically acceptable non-toxic salt thereof; associated with a 15 pharmaceutically acceptable carrier therefor.

45. A method of making a pharmaceutical formulation comprising bringing a compound as defined in one of Claims 1 to 28, 42 and 43 wherein Rp R a , R b and Z 1 are hydrogen, a .and a' are other than protected hydroxy, protected amino 20 or Protected aminomethyl and Q is other than a protected fftoiety; or a pharmaceutically acceptable non-toxic salt thereof; associated with a pharmaceutically acceptable · carrier therefor. *