Pyridinium thiomethyl substituted chepholosporin derivatives

Abstract

Novel cephem derivatives represented by the general formula ##STR1## in which the Acyl substituent is a group of the formula ##STR2## wherein Ar is a lipophilic optionally substituted phenyl, naphthyl, pyridyl or benzthiazolyl group; R.sup.1 is selected from certain optionally substituted aliphatic, aromatic, arylaliphatic or sugar moieties and R.sup.2 and R.sup.3 are each independently hydrogen, alkyl or aminoalkylcarbonylamino are gram-positive antibacterial agents, especially useful in the treatment of infectious diseases caused by methicillin-resistant Staphylococcus aureus (MRSA).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to new cephem derivatives represented by the general formula ##STR3## in which the Acyl substituent is a group of the formula ##STR4## where Ar is an optionally substituted lipophilic phenyl, naphthyl, pyridyl or benzthiazolyl group, R.sup.1 is selected from certain optionally substituted aliphatic, aromatic, arylaliphatic or sugar moieties and R.sup.2 and R.sup.3 are each independently hydrogen, alkyl or aminoalkylcarbonylamino. The derivatives are gram-positive antibacterial agents, especially useful in the treatment of diseases caused by methicillin-resistant Staphylococcus aureus (also referred to below as MRSA or methicillin-resistant S. aureus).

2. Description of the Prior Art

The literature discloses a vast number of cephem derivatives having a wide variety of C-3 and C-7 substituents. Applicants are not aware, however, of any literature disclosing compounds with the combination of C-3 and C-7 substituents found by applicants to give good activity against MRSA organisms. There are, however, references which disclose cephalosporins having the type of 7-substituents or the type of 3-substituents present in the compounds claimed in the present application.

For example, there are references which disclose applicants' C-7 substituents. Among such references disclosing 7-substituents of the type ##STR5## where Ar is an aromatic group are the following:

U.S. Pat. No. 4,056,676 discloses cephem derivatives of the general formula ##STR6## where Z is hydrogen or fluorine; and when Z is hydrogen, each of X and Y is hydrogen or chlorine selected so that the phenyl ring is substituted with 1 or 2 chlorine atoms and so that when one chlorine atom is present said chlorine atom is in the 3-position, and when two chlorine atoms are present said chlorine atoms are in the 3,4-, the 3,5- or the 2,5-positions; and when Z is fluorine, said fluorine is in the 3- or 4-positions of the phenyl ring and each of X and Y is hydrogen or chlorine selected so that when the phenyl ring is substituted with 1 or 2 chlorine atoms, one of the chlorine atoms is in the 3- or 4-position of the phenyl ring; R.sup.1 is hydrogen, dicyclohexylamine, or a pharmaceutically acceptable cation; and R is, inter alia, N-pyridino. Among the compounds specifically disclosed are those of the formulae: ##STR7## The compounds disclosed are said to be useful for treating and inhibiting the growth of MRSA organisms.

The cephalosporin derivative of the formula ##STR8## is disclosed in Antimicrobial Agents and Chemotherapy--1966, pg. 573-580 at page 576 (Compound No. 48).

J. Antibiotics, 26(12), 737-744, 1973, discloses the compound of the formula ##STR9##

U.K. Patent 998,265 discloses cephem derivatives of the general formula ##STR10## in which R.sup.1, taken alone, is --OH, C.sub.1 -C.sub.8 acyloxy, or tertiaryamino, R.sup.2 is --OH when R.sup.1 is --OH, R.sup.2 is --OH when R.sup.1 is C.sub.1 -C.sub.8 acyloxy, R.sup.2 is --O-- when R.sup.1 is tertiaryamino, R.sup.1 and R.sup.2, when taken together, are --O--, R.sup.3 and R.sup.4 represent hydrogen, alkyl radicals having from 1 to 6 carbon atoms, alkenyl radicals having from 2 to 6 carbon atoms, cycloalkyl radicals having from 5 to 7 carbon atoms, or alkoxyalkyl radicals having from 2 to 6 carbon atoms; n represents 0 to 4; and R.sup.5 represents an alkyl radical having from 1 to 6 carbon atoms, an alkenyl or alkynyl radical having from 2 to 6 carbon atoms, a cycloalkyl radical having 5 or 6 carbon atoms, phenyl, .beta.-furyl, .beta.-thienyl, thienyl, or naphthyl, or a fluoro, chloro, bromo, nitro, trifluoromethyl, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkylmercapto, or C.sub.1 -C.sub.4 alkoxy substitution product of such radicals.

U.K. Published Application No. 2,007,221 A discloses cephalosporin derivatives of the formula ##STR11## wherein Y is hydrogen, chlorine, bromine, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy; Z is a bond, oxygen or sulfur; W is hydrogen, methyl, amino, hydroxy, SO.sub.3 H or COOR.sub.4 wherein R.sup.4 is hydrogen or 5-indanyl with the proviso that when Z is oxygen or sulfur, W is other than hydroxy; R.sub.1 is hydrogen or methoxy; R.sub.2 is hydrogen, acetoxy, 1,3,4-thiadiazol-2-ylthio, 5-methyl-1,3,4-thiadiazol-2-ylthio, tetrazol-5-ylthio, 1-methyltetrazol-5-ylthio, 1,3,4-oxadiazol-2-ylthio, 5-methyl-1,3,4-oxadiazol-2-ylthio, 1,3,4-triazol-2-ylthio, 5-methyl-1,3,4-triazol-2-ylthio, 1,2,3-triazol-5-ylthio, pyridinium or 4-aminocarbonylpyridinium; R.sub.3 is hydrogen, a negative charge when R.sub.2 is pyridinium or 4-aminocarbonylpyridinium, a cation of an alkali metal or an alkaline earth metal, ammonium or organic ammonium cations, C.sub.1 -C.sub.4 alkyl, (C.sub.2 -C.sub.5 alkanoyloxy)methyl, (C.sub.2 -C.sub.5)alkanoylamino)methyl, [C.sub.2 -C.sub.5 alkanoyl(C.sub.1 -C.sub.4 alkoxy)carbonyl(C.sub.1 -C.sub.4 alkyl)-amino-methyl, p-(C.sub.2 -alkanoyloxy)benzylamino(C.sub.2 -C.sub.15 alkanoyloxy)methyl, (C.sub.1 -C.sub.4 alkyl)amino(C.sub.2 -C.sub.15 alkanoyloxy)methyl or di(C.sub.1 -C.sub.4 alkyl)amino(C.sub.2 -C.sub.15 alkanoyloxy)methyl; and pharmaceutically acceptable salts thereof.

U.S. Pat. No. 3,217,000 discloses cephem derivatives of the formula ##STR12## wherein Thi is 2-thienyl or 3-thienyl and R is a substituent at the 3 or 4 position of the pyridino ring selected from the group consisting of cyano, carboxy, carbamyl, N-methylcarbamyl, carbo(C.sub.1 -C.sub.4 alkoxy), hydroxy and (C.sub.1 -C.sub.4)alkanoyl; and the salts thereof with pharmaceutically acceptable acids.

There is also literature disclosing cephalosporins having 3-substituents of the type ##STR13## where R is an optionally substituted aliphatic or aromatic group. Among such references are those of the following:

U.S. Pat. No. 4,758,557 discloses cephalosporin derivatives of the general formula ##STR14## wherein A represents an alkanoyloxy group having 2-5 carbon atoms; a carbamoyloxy group; an azido group; or an unsubstituted or substituted pyridylthio group of the formula ##STR15## where n is 0 or an integer of 3-5; R.sup.1 and R.sup.2 may be the same or different and each represents a hydrogen atom, a halogen atom, a carboxyl group or an optionally halogen-substituted lower-alkyl group having 1-5 carbon atoms; or an unsubstituted or substituted pyridiniumthio group of the formula ##STR16## where n, R.sup.1 and R.sup.2 have the same meanings as above; R.sup.3 represents a linear or branched-chain alkyl group having 1-5 carbon atoms, a halogen-substituted alkyl group, a cyclopropyl group, a cyclopropylmethyl group, an alkenyl group, an oxygen atom or a group of (--CH.sub.2).sub.m --B where m is an integer of 0-3 and B represents a hydroxyl group, an alkoxy group, an amino group, an alkyl-substituted amino group, a carboxyl group, a carbamoyl group, a sulfonic acid group, a sulfonic acid amide group, a hydroxamic group, a cyano group, a thiol group, an alkylthio group, a methanesulfonylaminocarbonyl group or an acetamidosulfonyl group; or an unsubstituted or substituted pyridinium group of the formula ##STR17## where n has the same meaning as above; R.sup.4 and R.sup.5 may be the same or different and each represent a hydrogen atom, a linear or branched alkyl group having 1-5 carbon atoms, a carboxyl group, a carbamoyl group, a sulfonic acid group, a sulfonic acid amide group, a linear or branched alkylthio group having 1-5 carbon atoms, a halogen-substituted alkylthio group, a cycloalkanothio group, a carbamoylalkylthio group, an alkoxyalkylthio group or an alkyl-substituted aminoalkylthio group; or a 5- or 6-membered heterocyclicthio or bicycloheterocyclicthio group of the formula

--S-Het wherein Het represents an optionally substituted thiazole, isothiazole, 1,2,3-thiadiazole, 1,3,4-thiadiazole, 1,3,4-triazole, 1,2,3,4-tetrazole, pyrimidine, 1,2,4-triazine, benzothiazole, benzimidazole, benzoxazole, 1,3,4-triazaindolidine or 2,3-dihydro-1H-indolidinium group.

Illustrative of the compounds encompassed by U.S. Pat. No. 4,758,557 is MT0703 having the structure ##STR18## which is disclosed in J. Antibiotics 43(2), 189-198, 1990.

U.S. Pat. No. 4,786,633 discloses cephalosporin derivatives of the formula ##STR19## wherein R.sup.2 is a substituted or unsubstituted heterocyclic group having 1-3 hetero atoms selected from the group consisting of nitrogen and sulfur. The R.sup.2 group may be, for example, a group of the formula ##STR20## where R.sup.4 is lower alkenyl, lower alkyl, or a lower alkyl group substituted with a carbamoyl group and R.sup.5 and R.sup.6 are the same or different and each represent hydrogen or lower alkyl.

Published European Patent Application 409,164 A2 discloses cephalosporin derivatives of the formula ##STR21## wherein R.sup.1 is an amino group or acylamino; R.sup.2 is hydrogen or methoxy; R.sup.3 is hydrogen or a mono- or divalent substituent; R.sup.4 is optionally protected vic-dihydroxyaryl; R.sup.5 is straight or branched lower alkylene; R.sup.6 is hydrogen, a carboxy-protecting group or a negative charge when combined with Y; X is oxygen, sulfur, or sulfinyl; and Y is an anion or a negative charge when combined with R.sup.6 ; and the dotted line shows the presence or absence of a bond.

SUMMARY OF THE INVENTION

The present invention provides a novel series of cephem derivatives of the general formula ##STR22## wherein Ar is an aryl group selected from the group consisting of ##STR23## in which R.sup.4, R.sup.5, and R.sup.6 are each independently hydrogen, halogen, trihalomethyl, nitro, C.sub.1 -C.sub.6 alkyl, --(CH.sub.2).sub.n OR.sup.7 or --(CH.sub.2).sub.n SR.sup.7 ; n is an integer of from 1 to 6; R.sup.7 is hydrogen or C.sub.1 -C.sub.6 alkyl; R.sup.1 is selected from the group consisting of --CR.sup.8 R.sup.9 R.sup.10, --(CH.sub.2).sub.n CONR.sup.8 R.sup.9 and --(CH.sub.2).sub.n COR.sup.8 in which R.sup.8, R.sup.9 and R.sup.10 are each independently hydrogen, substituted or unsubstituted C.sub.1 -C.sub.15 alkyl, C.sub.2 -C.sub.15 alkenyl or C.sub.2 -C.sub.15 alkynyl, substituted or unsubstituted phenyl, phenyl(C.sub.1 -C.sub.6)alkyl, naphthyl or naphthyl(C.sub.1 -C.sub.6)alkyl or a sugar moiety of the formula ##STR24## in which said alkyl, alkenyl or alkynyl group, or the alkyl portion of said phenyl(C.sub.1 -C.sub.6)alkyl or naphthyl(C.sub.1 -C.sub.6)alkyl group can be substituted by one or more hydroxy groups and said phenyl or naphthyl group, or the phenyl or naphthyl portion of said phenyl(C.sub.1 -C.sub.6)alkyl or naphthyl(C.sub.1 -C.sub.6)alkyl group can be substituted by one or more hydroxy, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, halo or halo(C.sub.1 -C.sub.6)alkyl groups; n is as defined above; R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl, or amino(C.sub.1 -C.sub.6)alkylcarbonyl-amino; and R.sup.11 is hydrogen, an anionic charge or a carboxyl-protecting group, provided that when R.sup.11 is hydrogen or a protecting group, there is also present a counter ion; or a pharmaceutically acceptable salt or prodrug thereof. The compounds of formula I are antibacterial agents useful in the treatment of infections in humans and other animals caused by a variety of gram-positive bacteria, particularly methicillin-resistant S. aureus.

Also included in the invention are processes for preparing the compounds of formula I and pharmaceutical compositions containing said compounds in combination with pharmaceutically acceptable carriers or diluents.

DETAILED DESCRIPTION

The present invention provides novel cephem derivatives of general formula I above which are antibacterial agents useful in the treatment of infectious diseases in humans and other animals. The compounds exhibit good activity against a variety of gram-positive microorganisms, e.g. S. pneumoniae, S. pyrogenes, S. aureus, E. faecalis, E. faecium, S. epidermidis and S. hemolyticus, and are particularly useful against strains of methicillin-resistant S. aureus.

The compounds of formula I are characterized by a substituted pyridiniumthiomethyl group of the type ##STR25## at the 3-position of the cephem ring and a lipophilic 7-substituent of the type ##STR26## wherein Ar is an aromatic group selected from optionally substituted phenyl, naphthyl, pyridyl or benzthiazolyl.

To elaborate on the definitions for the substituents of the formula I compounds:

(a) "Halogen" includes chloro, bromo, fluoro and iodo, and is preferably chloro or bromo; (b) "Trihalomethyl" includes trichloromethyl, trifluoromethyl, tribromomethyl and triiodomethyl, but is preferably trifluoromethyl; (c) The aliphatic "alkyl", "alkoxy", "alkenyl" and "alkynyl" groups may be straight or branched-chains having the specified number of carbon atoms, e.g., in the case of C.sub.1 -C.sub.15 alkyl, the alkyl group may have from 1 to 15 carbon atoms. It is preferred that the groups have up to 6 carbon atoms and most preferably up to 4 carbon atoms.

The term "pharmaceutically acceptable salt" as used herein is intended to include the nontoxic acid addition salts with inorganic or organic acids, e.g. salts with acids such as hydrochloric, phosphoric, sulfuric, maleic, acetic, citric, succinic, benzoic, fumaric, mandelic, p-toluenesulfonic, methanesulfonic, ascorbic, lactic, gluconic, trifluoroacetic, hydroiodic, hydrobromic, and the like. Some of the compounds of the present invention have an acidic hydrogen and can, therefore, be converted with bases in a conventional manner into pharmaceutically acceptable salts. Such salts, e.g. ammonium, alkali metal salts, particularly sodium or potassium, alkaline earth metal salts, particularly calcium or magnesium, and salts with suitable organic bases such as lower alkylamines (methylamine, ethylamine, cyclohexylamine, and the like) or with substituted lower alkylamines (e.g. hydroxyl-substituted alkylamines such as diethanolamine, triethanolamine or tris-(hydroxymethyl)aminomethane), or with bases such as piperidine or morpholine, are also intended to be encompassed by the term "pharmaceutically acceptable salt".

Compounds of formula I in the form of acid addition salts may be written as ##STR27## where X.sup..crclbar. represents the acid anion and R.sup.11 is hydrogen or a carboxyl-protecting group. The counter anion X.sup..crclbar. may be selected so as to provide pharmaceutically acceptable salts for therapeutic administration.

The carboxyl-protecting group R.sup.11 is intended to include readily removable ester groups which have been employed to block a carboxyl group during the reaction steps used to prepare compounds I and which can be removed by methods which do not result in any appreciable destruction of the remaining portion of the molecule, e.g. by chemical or enzymatic hydrolysis, treatment with chemical reducing agents under mild conditions, irradiation with ultraviolet light or catalytic hydrogenation, etc. Examples of such protecting groups include benzhydryl, p-nitrobenzyl, 2-naphthylmethyl, allyl, benzyl, p-methoxybenzyl, trichloroethyl, silyl such as trimethylsilyl, phenacyl, acetonyl, o-nitrobenzyl, 4-pyridylmethyl and C.sub.1 -C.sub.6 alkyl such as methyl, ethyl or t-butyl. Included within such protecting groups are those which are hydrolyzed under physiological conditions such as pivaloyloxymethyl, acetoxymethyl, phthalidyl, indanyl, .alpha.-acetoxyethyl, .alpha.-pivaloyloxyethyl, and methoxymethyl. Compounds of formula I with such physiologically hydrolyzable carboxyl protecting groups are also referred to herein and in the claims as "prodrugs". Compounds of formula I where R.sup.11 is a physiologically removable protecting group are useful directly as antibacterial agents. Compounds where an R.sup.11 protecting group is not physiologically removable are useful intermediates which can be easily converted to the active form by conventional deblocking procedures well-known to those skilled in the art.

Compounds of formula I wherein a hydroxyl group of an R.sup.1 substituent is esterified with a group hydrolyzable under physiological conditions are also included within the scope of the term "prodrug" as used herein and in the claims. Such hydroxyl protecting groups may be employed, for example, to increase the solubility of the formula I compound. Illustrative of suitable ester "prodrugs" of this type are compounds of formula I wherein one or more hydroxy groups of the R.sup.1 substituent group are converted to sulfate (--OSO.sub.3 H) or phosphate (--OPO.sub.3 H.sub.2) groups. For example, an R.sup.1 substituent of this type could be --CH.sub.2 CH.sub.2 OSO.sub.3 H or --CH.sub.2 CONHCH.sub.2 CH.sub.2 OPO.sub.3 H.sub.2.

A preferred embodiment of the present invention comprises compounds of formula I wherein Ar is ##STR28## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula ##STR29## wherein R.sup.1 is --CR.sup.8 R.sup.9 R.sup.10 in which R.sup.8, R.sup.9 and R.sup.10 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl, hydroxy(C.sub.1 -C.sub.6)alkyl, C.sub.2 -C.sub.6 alkenyl, phenyl(C.sub.1 -C.sub.6)alkyl, hydroxyphenyl(C.sub.1 -C.sub.6)alkyl or dihydroxyphenyl(C.sub.1 -C.sub.6)alkyl; R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof. Within this embodiment, the most preferred compounds are those in which Ar is ##STR30## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula ##STR31## wherein R.sup.1 is --(CH.sub.2).sub.n CONR.sup.8 R.sup.9 in which R.sup.8 and R.sup.9 are each independently hydrogen, hydroxy(C.sub.1 -C.sub.6)alkyl, ##STR32## n is an integer from 1 to 6; and R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof. Within this embodiment, the most preferred compounds are those in which Ar is ##STR33## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula ##STR34## wherein R.sup.1 is --(CH.sub.2).sub.n COR.sup.8 in which R.sup.8 is C.sub.1 -C.sub.6 alkyl; n is an integer of from 1 to 6; and R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof. Within this embodiment, the most preferred compounds are those in which Ar is ##STR35## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

Another preferred embodiment comprises the compounds of formula I wherein the 3-substituent has the formula ##STR36## wherein R.sup.1 is ##STR37## R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; or a pharmaceutically acceptable salt or prodrug thereof. Within this embodiment, the most preferred compounds are those in which Ar is ##STR38## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

The preferred individual compounds of the present invention, all of which have an MIC vs a representative MRSA strain of <8 .mu.g/ml, are listed below:

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)aceta-mido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 1) 1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 3) 1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 4) 1-(1-Prop-2-enyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 5) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 6) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 7) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 8) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3-bromophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 9) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-chloro-5-trifluoro-methylphenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 10) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(1-naphthylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 11) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-benzthiazolylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 12) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3,5,6-trichloropyridin-2-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 13) 1-Acetylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 14) 1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 15) 1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 16) 1-(3-Hydroxy-1-propyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 17) 1-(4-Hydroxy-1-butyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 18) 1-[2-Hydroxy-1-(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 19) 1-[2-Hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 2) 1-[(N,N-di-2-Hydroxyethyl)carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 20) 1-[N-[2-Hydroxy-1-(hydroxymethyl)ethyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 21) 1-[N-2-[2-Deoxy-D-galactopyranosyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 22) 1-[N-3-(3-Deoxy-D-glucopyranosyl)carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 23) 1-[1-(1-Deoxy-D-glucitolyl)]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichloro-phenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 24) 1-[2-(4-Hydroxyphenyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 25) 1-(2-Phosphonoxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 26) 1-(2-Phosphonoxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]-methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 27) 1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichloro-phenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 28) 1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 29) 1-[2-(3,4-Dihydroxyphenyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 30) 1-[2-(Phenylethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 31); 1-(2-Hydroxy-1-ethyl)-2,6-dimethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 32) 1-[2-(3-Hydroxyphenylethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichloro-phenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 33) 1-[2-(3-Methoxy-4-hydroxyphenylethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 34) 1-[2-(3,5-Dimethoxy-4-hydroxyphenylethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 35); and 1-Methyl-3-aminomethylcarbonylamino-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl)methylthio)]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 36)

The more preferred individual compounds of the present invention, all of which have a MIC.ltoreq.8 .mu.g/mL and a PD.sub.50 .ltoreq.5 mg/kg against a representative strain of MRSA, are listed below:

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 1) 1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 3) 1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 4) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 7) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 8) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3-bromophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 9) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-chloro-5-trifluoro-methylphenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 10) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(1-naphthylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 11) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-benzthiazolylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 12) 1-Acetylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 14) 1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound Example 15) 1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 16) 1-(3-Hydroxy-1-propyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 17) 1-(4-Hydroxy-1-butyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 18) 1-[2-Hydroxy-1-(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 19) 1-[2-Hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 2) 1-[(N,N-di-2-Hydroxyethyl)carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 20) 1-[N-[2-Hydroxy-1-(hydroxymethyl)ethyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabi-cyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 21) 1-[N-2-[2-Deoxy-D-galactopyranosyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 22) 1-[1-(1-Deoxy-D-glucitolyl)]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 24) 1-[2-(4-Hydroxyphenyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 25) 1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 29); and 1-Methyl-3-aminomethylcarbonylamino-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl)methylthio)]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 36).

The most preferred individual compounds of the present invention are listed below:

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 4) 1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3-bromophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 9) 1-[N-[2-Hydroxy-1-(hydroxymethyl)ethyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo-[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 21) 1-[N-2-[2-Deoxy-D-galactopyranosyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 22) 1-[1-(1-Deoxy-D-glucitolyl)]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 24); and 1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof (compound of Example 29).

The compounds of the present invention can be made by conventional methods. Two suitable procedures are summarized by the following reaction scheme: ##STR39##

To elaborate on the above processes, thiol VII is converted into the arylthioacetic acid derivative VI, e.g. by treatment with bromoacetic acid under basic conditions (e.g. aqueous sodium or potassium hydroxide). The reaction temperature for this step is typically between 20.degree. and 100.degree. C. Starting thiol VII is commercially available or can be prepared according to known literature procedures. Following acidification of the reaction mixture, the product VI is typically isolated by crystallization or, if necessary, it can be purified by chromatography.

Arylthioacetic acid VI is then coupled with a suitable cephem intermediate having a suitable 3-substituent leaving group. For example, the leaving group may be acetoxy or halo. In the preferred embodiment illustrated by the reaction scheme, the cephem intermediate is the 3-chloromethyl cephem V, but other suitable cephem intermediates with equivalent leaving groups at the 3-position could also be employed. The cephem intermediate V may be acylated with VI or a reactive derivative thereof by conventional acylation procedures well-known in the cephalosporin art to give N-acylated intermediate IV. In addition to using the free arylthioacetic acid, e.g. with a suitable condensing agent such as dicyclohexylcarbodiimide, acylating agent VI may also be employed in the form of equivalent acylating derivatives such as an acid anhydride, mixed anhydride, activated ester or acid halide. The cephem intermediate preferably has the carboxyl group protected by a conventional carboxyl-protecting group which can be readily removed. Examples of such protecting groups are discussed above and include benzyl, 4-nitrobenzyl, 4-methoxybenzyl, diphenylmethyl, allyl, and the like. Other examples of suitable protecting groups are disclosed in Protective Groups in Organic Synthesis, Theodora W. Greene (John Wiley & Sons, 1981), Chapter 5. In one embodiment, intermediate V may be acylated with acid VI in the presence of dicyclohexylcarbodiimide and in an inert solvent such as tetrahydrofuran or dichloromethane. The reaction temperature is typically between -20.degree. and 50.degree. C. Upon completion of the reaction, insoluble material is removed by filtration, the filtrate is concentrated, and the residue is treated with a relatively non-polar solvent such as diethyl ether or ethyl acetate resulting in precipitation of the desired product. Alternatively, acid VI may be converted to the corresponding acid chloride, for example by treatment with thionyl chloride with or without a solvent such as dichloromethane, followed by coupling with cephem amine V in the presence of a base such as triethylamine or N-methylmorpholine to give intermediate IV. Cephem IV is typically isolated by aqueous workup followed by trituration of the compound with a relatively non-polar solvent such as diethyl ether or ethyl acetate. This intermediate may be used in the next reaction step as the X=chloride derivative, or can be converted to the X=bromide or X=iodide derivative by treatment with the appropriate metal halide in a solvent such as acetone.

Conversion of cephem IV to the target quaternary cephems I may be accomplished by two different methods. One method entails displacement of an appropriate 3-substituent leaving group with 4-mercaptopyridine followed by quaternization of the pyridyl nitrogen, followed by deprotection of the cephem carboxylate ester. For example, intermediate IV (X=Cl) may be converted to the corresponding iodide by treatment with sodium iodide in a solvent such as acetone at a temperature between -20.degree. and 50.degree. C. The iodide is typically used without purification. Reaction of the iodide with optionally-substituted 4-mercaptopyridine in an inert solvent such as tetrahydrofuran or dimethylformamide at a temperature between -20.degree. and 50.degree. C. then affords the thiopyridyl derivative II. Alternatively, cephem IV (X=Cl) is treated with optionally substituted 4-mercaptopyridine and sodium iodide in a one-pot reaction to give intermediate II. Reaction of thiopyridyl II with a reactive alkylating agent provides the quaternary cephem intermediate I'. Examples of alkylating agents are primary alkyl halides such as methyl iodide, allylic halides such as allyl bromide, halomethyl ethers such as chloromethyl methyl ether and .alpha.-halocarbonyl derivatives such as iodoacetamide and 1-bromoacetone. The alkylation reaction is carried out in an inert solvent such as acetone, dimethylformamide or tetrahydrofuran and is run at temperatures between -20.degree. and 100.degree. C. Removal of the cephem carboxylate ester protecting group to give I is then accomplished under acidic conditions. For example, when R is diphenylmethyl or 4-methoxybenzyl, I is obtained upon treatment of I' with trifluoroacetic acid neat or in an inert solvent such as methylene chloride. A reagent such as anisole may also be employed to scavenge the liberated ester protecting group. The deprotection may also be carried out by treatment with other protic acids such as hydrochloric acid in a solvent such as methanol. The final product is typically isolated by precipitation or crystallization. In some cases, cephem I is purified by column chromatography, for example on reversed-phase adsorbent.

In a second method of preparing quaternary cephems I, intermediate IV is deprotected under acidic conditions, followed by reaction of the resulting intermediate IV' with a thiopyridone derivative III. For example, when R is diphenylmethyl or 4-methoxybenzyl, treatment of cephem intermediate IV under acidic conditions as described above provides cephem acid IV'. Reaction of IV' with a thiopyridone derivative III in a solvent such as dimethylformamide, dimethyl sulfoxide, ethanol, methanol, or other appropriate solvents at a temperature between -20.degree. and 100.degree. C. affords target quaternary cephem I. Thiopyridones III are typically prepared according to a method analogous to that described in T. Takahashi et al., European Patent Application No. 209751 and I. E. El-Kholy et al., J. Heterocyclic Chem., Vol. 11, p. 487(1974). This procedure entails reaction of 4-thiopyrone (EP 209751) with an appropriate primary amine in a solvent such as aqueous methanol or ethanol at a temperature ranging between 0.degree. and 78.degree. C. The primary amine may be in the form of a zwitterion in cases where there is a free acid group present in the molecule. In these cases, a base such as sodium hydroxide, sodium bicarbonate or pyridine is added to form the free amine in situ. The product may be isolated as its sodium salt by evaporation of volatile solvents, followed by trituration with a solvent such as diethyl ether or ethyl acetate. Alternatively, the reaction mixture may be acidified and extracted with an organic solvent to afford the product as the free carboxylic acid. If the carboxylate group is protected as an ester, the amine may be free or present as an acid salt. In the latter case, a base such as sodium hydroxide, sodium bicarbonate or pyridine is added to form the free amine in situ. The product is typically isolated by precipitation or by reversed phase column chromatography following removal of volatile solvents.

Some of the thiopyridone derivatives of formula III are novel compounds and are intended to be a further aspect of the present invention. In particular, the following compounds are encompassed by the present invention: ##STR40##

It will be understood that where the substituent groups used in the above reactions contain certain reaction-sensitive functional groups such as amino or hydroxy groups which might result in undesirable side-reactions, such groups may be protected by conventional protecting groups known to those skilled in the art. Such protecting groups are removed by conventional procedures known in the art. Suitable protecting groups and methods for their removal are illustrated, for example, in the reference work cited above in connection with carboxyl-protecting groups.

The desired end-product of formula I may be recovered either as the zwitterion or in the form of a pharmaceutically acceptable acid addition salt, e.g. by addition of the appropriate acid such as HCl, HI or methanesulfonic acid to the zwitterion. Compounds of formula I where R.sup.11 is hydrogen or an anionic charge, or a pharmaceutically acceptable salt thereof, may be converted by conventional procedures to a corresponding compound where R.sup.11 is a physiologically hydrolyzable ester group.

The novel cephalosporin derivatives of general formula I wherein R.sup.11 is hydrogen, an anionic charge or a physiologically hydrolyzable carboxyl-protecting group, or the pharmaceutically acceptable salts or prodrugs thereof, are potent antibiotics active against many gram-positive bacteria. While they may be used, for example, as animal feed additives for promotion of growth, as preservatives for food, as bactericides in industrial applications, for example in waterbased paint and in the white water of paper mills to inhibit the growth of harmful bacteria, and as disinfectants for destroying or inhibiting the growth of harmful bacteria on medical and dental equipment, they are especially useful in the treatment of infectious disease in humans and other animals caused by the gram-positive bacteria sensitive to the new derivatives. Because of their excellent activity against MRSA organisms, they are particularly useful in the treatment of infections resulting from such bacteria.

The pharmaceutically active compounds of this invention may be used alone or formulated as pharmaceutical compositions comprising, in addition to the active cephem ingredient, a pharmaceutically acceptable carrier or diluent. The compounds may be administered by a variety of means, for example, orally, topically or parenterally (intravenous or intramuscular injection). The pharmaceutical compositions may be in solid form such as capsules, tablets, powders, etc. or in liquid form such as solutions, suspensions or emulsions. Compositions for injection, the preferred route of delivery, may be prepared in unit dose form in ampules or in multidose containers and may contain additives such as suspending, stabilizing and dispersing agents. The compositions may be in ready-to-use form or in powder form for reconstitution at the time of delivery with a suitable vehicle such as sterile water.

The dosage to be administered depends, to a large extent, on the particular compound being used, the particular composition formulated, the route of administration, the nature and condition of the host and the particular situs and organism being treated. Selection of the particular preferred dosage and route of application, then, is left to the discretion of the physician or veterinarian. In general, however, the compounds may be administered parenterally or orally to mammalian hosts in an amount of from about 50 mg/day to about 20 g/day. Administration is generally carried out in divided doses, e.g., three to four times a day, analogous to dosing with a cephalosporin such as cefotaxime.

To illustrate the antibacterial properties of the compounds of the present invention, the following biological data is presented below.

IN VITRO ACTIVITY

Samples of the compounds prepared below in Examples 1-36 after solution in water and dilution with Nutrient Broth were found to exhibit the following ranges of Minimum Inhibitory Concentrations (MIC) versus the indicated microorganisms as determined by tube dilution. The MICs were determined using a broth micro dilution assay in accordance with that recommended by the National Committee for Clinical Laboratory Standards (NCCLS). Mueller-Hinton medium was used except for Streptococci which was tested in Todd Hewitt broth. The final bacterial inoculate contained approximately 5.times.10.sup.5 cfu/ml and the plates were incubated at 35.degree. C. for 18 hours in ambient air (Streptococci in 5% CO.sub.2). The MIC was defined as the lowest drug concentration that prevented visible growth.

______________________________________ MIC range inMicroorganism mcg/ml______________________________________S. aureus methicillin resistant A27223 0.125-8S. pneumoniae A9585 0.0001-0.06S. pyogenes A9604 0.0001-0.06E. faecalis A20688 0.06-8E. faecium A24885 0.25-8S. aureus A9537, penicillinase negative 0.001-0.125S. aureus A15090, penicillinase positive 0.015-1S. epidermidis A24548 0.001-0.125S. epidermidis A25783, methicillin resistant 0.03-1S. hemolyticus A21638 0.001-0.5S. hemolyticus A27235, methicillin resistant 0.125-8______________________________________

IN VIVO ACTIVITY

The in vivo therapeutic efficacy of the compounds prepared in Examples 1-36 below after intramuscular injection to mice experimentally infected with the representative MRSA strain A27223 was also measured.

The determination of the effectiveness of antimicrobial agents in Staphylococcus aureus systemic infection in mice

Organisms:

The test organism, MRSA strain A27223 used to generate systemic infection in mice, is grown on two large Brain Heart Infusion Agar plates. On each plate, 0.5 ml of frozen stock culture is plated out. Plates are then incubated for 18 hours at 30.degree. C. The next day each plate is washed with 20 ml of Brain Heart Infusion Broth and then pooled together. A microscopic direct count of microorganism is done using a 1:1000 dilution of plate wash. After a direct count is obtained, the number of organisms per milliliter is calculated. The count is adjusted to the desired amount of inoculum by diluting in 4% hog mucin. The desired challenge (amount of organisms given to mice) is 2.4.times.10.sup.8 cfu/0.5 ml/mouse for MRSA strain A27223. The mice are infected intraperitoneally with 0.5 ml of challenge. Ten non-treated infected mice are used as controls.

Mice:

Mice used are male ICR mice. The average weight of the animals is from 20 to 26 grams.

Drug preparation and treatment:

Compounds are tested at 4 dose levels, (25, 6.25, 1.56, and 0.39 mg/kg) and prepared in 5% cremophor, unless otherwise specified. Vancomycin is used as the control compound, and is dosed at 6.25, 1.56, 0.39, and 0.098 mg/kg. It is prepared in 0.1M phosphate buffer. There are five infected mice per dose level, and they are treated with 0.2 ml of the test compound, preferably by intramuscular injection. Treatment begins 15 minutes and 2 hours post-infection.

Test duration:

A PD.sub.50 (the dose of drug given which protects 50% of mice from mortality) runs for 5 days. During this time, mortality of mice are checked every day and deaths are recorded. The cumulative mortality at each dose level is used to calculate a PD.sub.50 value for each compound. Surviving mice are sacrificed at the end of day 5 by CO.sub.2 inhalation.

Calculation:

Actual calculation of PD.sub.50 is performed with a computer program using the Spearman-Karber procedure.

Results:

The in vivo efficacy, expressed as the PD.sub.50 value, ranged from about 0.6 to about 22 mg/kg (for certain compounds, more than one test was carried out; the indicated range is for at least one test result when multiple tests were done).

ILLUSTRATIVE EXAMPLES

The following examples illustrate the invention, but are not intended as a limitation thereof. The abbreviations used in the examples are conventional abbreviations well-known to those skilled in the art. Some of the abbreviations used are as follows:

______________________________________h = hour(s)mol = mole(s)mmol = mmole(s)g = gram(s)THF = tetrahydrofuranL = liter(s)mL = milliliter(s)Et.sub.2 O = diethyl etherEtOAc = ethyl acetateMeOH = methanolDMF = dimethylformamide______________________________________

In the following examples, all temperatures are given in degrees Centigrade. Melting points were determined on an electrothermal apparatus and are not corrected. Proton and carbon-13 nuclear magnetic resonance (.sup.1 H and .sup.13 C NMR) spectra were recorded on a Bruker AM-300 or a Varian Gemini 300 spectrometer. All spectra were determined in CDCl.sub.3, DMSO-d.sub.6, CD.sub.3 OD, or D.sub.2 O unless otherwise indicated. Chemical shifts are reported in .delta. units relative to tetramethylsilane (TMS) or an internal solvent peak and interproton coupling constants are reported in Hertz (Hz). Splitting patterns are designated as follows: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br, broad peak; dd, doublet of doublets and dt, doublet of triplets. Infrared spectra were determined on a Perkin-Elmer 1800 FT-IR spectrometer from 4000 cm.sup.-1 to 400 cm.sup.-1, calibrated to 1601 cm.sup.-1 absorption of a polystyrene film, and are reported in reciprocal centimeters (cm.sup.-1). Mass spectra were recorded on a Kratos MS-50 or a Finnegan 4500 instrument utilizing direct chemical ionization (DCI, isobutene) or fast atom bombardment (FAB). Ultraviolet spectra were determined on a Hewlett Packard 8452 diode array spectrophotometer in the solvent indicated.

Analytical thin-layer chromatography (TLC) was carried out on precoated silica gel plates (60F-254) and visualized using UV light, iodine vapors, and/or staining by heating with methanolic phosphomolybdic acid. Column chromatography, also referred to as flash chromatography, was performed in a glass column using finely divided silica gel at pressures somewhat above atmospheric pressure with the indicated solvents. Reversed-phase analytical thin-layer chromatography was carried out on precoated reverse phase plates and visualized using UV light or iodine vapors. Reversed-phase column chromatography was performed in a glass column using Baker Octadecyl (C.sub.18), 40 .mu.m.

Example 1

1-Methyl-4-[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)aceta-mido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium chloride ##STR41## A. 2,5-Dichlorophenylthioacetic acid

A mixture of 2,5-dichlorothiophenol (10.3 g, 57.5 mmol) and bromoacetic acid (8.03 g, 57.8 mmol) in water (225 mL) was treated with 10N NaOH (13 mL, 130 mmol) and the mixture was heated at 100.degree. C. for 1 h. The reaction mixture was then cooled to 0.degree. C. and acidified to pH 1 with 6N HCl. The product precipitated and was collected by filtration to give 13.0 g (95% yield) of 2,5-dichlorophenylthioacetic acid as white crystals, m.p. 118.degree. C. .sup.1 H NMR (300 MHz, CDCl.sub.3) .delta.3.74 (s, 2 H), 7.15 (dd, J=2, 9 Hz, 1H), 7.32 (d, J=9 Hz, 1H), 7.36 (d, J=2 Hz, 1H). Anal. Calcd. for C.sub.8 H.sub.6 O.sub.2 SCl.sub.2 : C, 40.53; H, 2.55. Found: C, 40.46; H, 2.64.

B. (6R)-trans-3-Chloromethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester Method a:

A solution of 2,5-dichlorophenylthioacetic acid (13.0 g, 54.9 mmol) in methylene chloride (55 mL) and thionyl chloride (10 mL, 137 mmol) was heated at reflux for 3 h. The reaction mixture was allowed to cool to room temperature and was concentrated in vacuo. The residue was evaporated two times from toluene to give 14 g of 2,5-dichlorophenylthioacetyl chloride (100% yield) as a slightly colored product which was used in the next step without purification. .sup.1 H NMR (300 MHz, CDCl.sub.3) .delta.4.13 (s, 2H), 7.22 (dd, J=2, 9 Hz, 1H), 7.35 (d, J=9 Hz, 1H), 7.39 (d, J=2 Hz, 1H).

(6R)-trans-3-Chloromethyl-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester, HCl salt was stirred in a biphasic mixture of EtOAc and saturated NaHCO.sub.3 for 0.5 h. The layers were separated, and the organic solution was dried over anhydrous MgSO.sub.4, filtered, and concentrated to dryness. The free base (9.15 g, 22.0 mmol) was dissolved in THF (200 mL), cooled to 0.degree. C., and treated with N-methylmorpholine (3.34 g, 33.0 mmol) and 2,5-dichlorophenylthioacetyl chloride (6.75 g, 26.4 mmol). The reaction mixture was stirred for 1 h at 0.degree. C., diluted with EtOAc (1000 mL) and washed with water (1000 mL) and brine (100 mL). The organic solution was then dried (MgSO.sub.4) and the solvents were evaporated in vacuo. The residue was stirred with ether (100 mL). The product solidified and was collected by filtration to give 12.0 g (86% yield) of (6R)-trans-3-chloromethyl-7-[(2,5-dichlorophenyl)-thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester, m.p. 120.degree. C. .sup.1 H NMR (300 MHz, CDCl.sub.3) .delta.3.43 (d, J=18 Hz, 1H), 3.59 (d, J=18 Hz, 1H), 3.69 (d, J=17 Hz, 1H), 3.79 (d, J=17 Hz, 1H), 4.36 (d, J=12 Hz, 1H), 4.41 (d, J=12 Hz, 1H), 4.98 (d, J=5 Hz, 1H), 5.81 (dd, J=5, 9 Hz, 1H), 6.98 (s, 1H), 7.14-7.44 (m, 14H). Anal. Calcd for C.sub.29 H.sub.23 N.sub.2 O.sub.4 S.sub.2 Cl.sub.3 : C, 54.94; H, 3.66; N, 4.42. Found: C, 55.18; H, 3.84; N, 4.62.

Method b:

(6R)-trans-3-Chloromethyl-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester, HCl salt (Otsuka, 248 g, 0.55 mol) was treated with NaHCO.sub.3 (56 g, 0.66 mol) in water (1.6 L) at 0.degree. C. The mixture was stirred at 0.degree. C. for 0.5 h and then CH.sub.2 Cl.sub.2 (1.5 L) was added. The biphasic mixture was filtered through Celite and the Celite pad was washed with CH.sub.2 Cl.sub.2 (2 L total). The layers were separated and the organic solution was dried over anhydrous MgSO.sub.4, filtered, and concentrated to a volume of ca. 2 L. The free amine solution was then added to a mixture of 2,5-dichlorothiophenylacetic acid (130 g, 0.55 mol) and dicyclohexylcarbodiimide (144 g, 0.70 mol) in THF (1 L) at room temperature. The reaction mixture was stirred for 2.5 h and then was filtered through Celite, washing the Celite pad with several portions of acetone. The filtrate was concentrated in vacuo to give a solid mass. The solid was slurried in Et.sub.2 O and then collected by filtration, washing the solid with several portions of Et.sub.2 O. The solid was dried under high vacuum over P.sub.2 O.sub.5 to give 268 g (77% yield) of (6R)-trans-3-chloromethyl-7-[(2,5-dichlorophenyl)-thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester (see above for analytical data).

C. (6R)-trans-3-(4-Pyridylthiomethyl)-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester

A solution of (6R)-trans-3-chloromethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester (6.00 g, 9.46 mmol) in acetone (100 mL) was treated with sodium iodide (4.26 g, 28.4 mmol). The mixture was stirred at 20.degree. C. for 3 h and then condensed under reduced pressure to a volume of 50 mL. The concentrated solution was diluted with EtOAc (200 mL) and washed with ice water (100 mL). The organic solution was washed with saturated NaHSO.sub.4 (20 mL), dried (MgSO.sub.4), and evaporated under reduced pressure. The residue was stirred with ether (30 mL). The product solidified and was collected by filtration to give 6.40 g of (6R)-trans-3-iodomethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester (93% yield) as a buff solid, m.p. 124.degree. C. .sup.1 H NMR (300 MHz, CDCl.sub.3) .delta.3.43 (d, J=18 Hz, 1H), 3.69 (d, J=17 Hz, 1H), 3.70 (d, J=18 Hz, 1H), 3.78 (d, J=17 Hz, 1H), 4.27 (d, J=9 Hz, 1H), 4.33 (d, J=9 Hz, 1H), 4.96 (d, J=5 Hz, 1H), 5.75 (dd, J=5, 9 Hz, 1H), 7.00 (s, 1H), 7.20-7.46 (m, 14H). Anal. Calcd. for C.sub.29 H.sub.23 N.sub.2 O.sub.4 S.sub.2 Cl.sub.2 I: C, 8.01; H, 3.20; N, 3.86. Found: C, 48.00; H, 3.14; N, 3.76.

(6R)-trans-3-Iodomethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester (3.00 g, 4.14 mmol) was dissolved in THF (50 mL) at 0.degree. C. and treated with 4-mercaptopyridine (0.504 g, 4.54 mmol). A solution of 2,6-lutidine (0.576 g, 5.38 mmol) in THF (1 mL) was added next, and the reaction mixture was stirred at 0.degree. C. for 0.5 h and then at 20.degree. C. for 1 h. The mixture was diluted with ethyl acetate (500 mL) and the organic solution was washed with water (2.times.500 mL) and brine (100 mL). The solution was then dried (MgSO.sub.4) and evaporated under reduced pressure to give an oil which was treated with Et.sub.2 O (50 mL) to give a solid. The solid was collected by filtration and purified by column chromatography on silica gel (CH.sub.2 Cl.sub.2 to 30% EtOAc/CH.sub.2 Cl.sub.2) to give 1.50 g of (6R)-trans-3-[(4-pyridylthiomethyl]-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester as a tan solid (49% yield), m.p. 122.degree. C. .sup.1 H NMR (300 MHz, CDCl.sub.3) .delta.3.37 (d, J=18 Hz, 1H), 3.52 (d, J=18 Hz, 1H), 3.68 (d, J=17 Hz, 1H), 3.76 (d, J=17 Hz, 1H), 3.96 (d, J=13 Hz, 1H), 4.16 (d, J=13 Hz, 1H), 4.93 (d, J=5 Hz, 1H), 5.76 (dd, J=5, 9 Hz, 1H), 6.95-7.42 (m, 16H), 7.49 (d, J=9 Hz, 1H), 8.29 (d, J=6 Hz, 2H). Anal. Calcd. for C.sub.34 H.sub.27 N.sub.3 O.sub.4 S.sub.3 Cl.sub.2 : C, 57.62; H, 3.84; N, 5.93. Found: C, 57.27; H, 3.68; N, 5.79.

D. 1-Methyl-4-[(6R)-trans-2-(diphenylmethylcarboxy)-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium iodide

A solution of (6R)-trans-3-[(4-pyridylthiomethyl]-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester (0.50 g, 0.70 mmol) in dry acetone (50 mL) was treated with iodomethane (5 mL). The solution was stirred at 20.degree. C. for 5 h and the solvents were then evaporated under reduced pressure. The residue was treated with ethyl acetate (5 mL), and the resulting solid was collected by filtration to give 0.48 g of 1-methyl-4-[(6R)-trans-2-(diphenylmethylcarboxy)-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium iodide as a tan solid (80% yield), m.p. 110.degree. C. .sup.1 H NMR (300 MHz, CDCl.sub.3) .delta.3.55 (d, J=18 Hz, 1H), 3.80 (d, J=18 Hz, 1H), 3.93 (s, 2H), 4.17 (s, 3H), 4.22 (d, J=12 Hz, 1H), 4.29 (d, J=12 Hz, 1H), 5.21 (d, J=5 Hz, 1H), 5.80 (dd, J=5, 8 Hz, 1H), 6.95 (s, 1H). 7.21-7.48 (m, 13H), 7.84 (d, J=7 Hz, 2H), 8.63 (d, J=7 Hz, 2H), 9.32 (d, J=8 Hz, 1H).

E. 1-Methyl-4-[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium chloride

A solution of 1-methyl-4-[(6R)-trans-2-(diphenylmethylcarboxy)-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium iodide (0.48 g, 0.56 mmol) in methylene chloride (10 mL) was cooled to 0.degree. C. and treated with anisole (2 mL) and trifluoroacetic acid (7 mL). The solution was stirred at 0.degree. C. for 1 h and then the solvents were removed under reduced pressure. The residue was treated with Et.sub.2 O to afford a tan solid which was purified by treatment with activated charcoal and Amberlite IRA-400 (Cl) ion-exchange resin in 1:1 methanol-acetone followed by filtration and concentration of the filtrate to give 0.28 g of 1-methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium, HCl salt as a brown solid (85% yield). .sup.1 H NMR (300 MHz, DMSO-d.sub.6) .delta.3.49 (d, J=18 Hz, 1H), 3.73 (d, J=18 Hz, 1H), 3.91 (s, 2H), 4.17 (s, 3H), 4.37 (s, 2H), 5.13 (d, J=5 Hz, 1H), 5.68 (dd, J=5, 8 Hz, 1H), 7.23 (dd, J=2, 8 Hz, 1H), 7.46-7.49 (m, 2H), 7.98 (d, J=7 Hz, 2H), 8.70 (d, J=7 Hz, 2H), 9.28 (d, J=8 Hz, 1H). Anal. Calcd. for C.sub.22 H.sub.19 N.sub.3 O.sub.4 S.sub.3 Cl.sub.2.2.2 H.sub.2 O.HCl: C, 41.78; H, 3.89; N, 6.64. Found: C, 41.62; H, 3.62; N, 6.28.

Example 2

1-[2-Hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium chloride ##STR42## A. (6R)-trans-3-Chloromethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

A slurry of (6R)-trans-3-chloromethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate, diphenylmethyl ester (10.0 g, 15.8 mmol) in CH.sub.2 Cl.sub.2 (200 mL) at 0.degree. C. was treated with anisole (24 mL) and then trifluoroacetic acid (80 mL). The resulting solution was stirred for 1 h at 0.degree. C. and then concentrated under reduced pressure. The residue was stirred with Et.sub.2 O, and the resulting solid was collected by filtration to give 5.20 g of (6R)-trans-3-chloromethyl-7-[(2,5-dichlorophenyl)thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid as a white solid (70% yield), m.p. 125.degree. C. .sup.1 H NMR (300 MHz, DMSO-d.sub.6) .delta.3.51 (d, J=18 Hz, 1H), 3.70 (d, J=18 Hz, 1H), 3.91 (s, 2H), 4.52 (d, J=11 Hz, 1H), 4.58 (d, J=11 Hz, 1H), 5.13 (d, J=5 Hz, 1H), 5.70 (dd, J=5, 8 Hz, 1H), 7.24 (dd, J=2, 8 Hz, 1H), 7.47 (dd, J=2, 8 Hz, 1H), 9.28 (d, J=8 Hz, 1H).

B. 1-[2-Hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium chloride

A solution of 4-thiopyrone (0.500 g, 4.46 mmol) (ref: European Patent Application No. 209751) in absolute ethanol (15 mL) was placed under a nitrogen atmosphere and treated with tris(hydroxymethyl)aminomethane (0.541 g, 4.46 mmol). The reaction mixture was heated at reflux for 2 h, and then allowed to cool to room temperature. Upon cooling a precipitate was visible. Acetone (30 mL) was added, and the heterogeneous mixture was stirred for 1 min. The precipitate was collected by filtration, washed with acetone, and dried in vacuo to give 0.495 g (52% yield) of 1-[2-hydroxy-1,1-di(hydroxymethyl)ethyl]-4-thiopyridone as a golden solid. .sup.1 H NMR (300 MHz, DMSO-d.sub.6) .delta.3.78 (d, J=5 Hz, 6H), 5.17 (t, J=5 Hz, 3H), 7.13 (d, J=7 Hz, 2H), 7.76 (d, J=7 Hz, 2H); .sup.13 C NMR (75 MHz, DMSO-d.sub.6) .delta.60.91, 71.68, 129.59, 134.69, 188.48; IR (KBr) 3406, 1624, 1084 cm.sup.-1 ; FAB MS m/z 216 (MH.sup.+). Anal. Calcd. for C.sub.9 H.sub.13 NO.sub.3 S: C, 50.22; H, 6.09; N, 6.51. Found: C, 50.13; H, 6.15; N, 6.53.

A solution of 1-[2-hydroxy-1,1-di(hydroxymethyl)ethyl]-4-thiopyridone (0.344 g, 1.60 mmol) in DMF (6 mL) was added to (6R)-trans-3-chloromethyl-7-[(2,5-dichlorophenyl)-thioacetamido]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid (0.702 g, 1.50 mmol). The mixture was stirred for 4 h, and then the solvent was removed in vacuo, keeping the temperature below 30.degree. C. The tarry residue was stirred with 40 mL of Et.sub.2 O until a yellow powder resulted. The powder was collected by filtration, and then stirred with acetone for 30 min. The resulting gummy solid was collected by filtration and washed with Et.sub.2 O. The solid was slurried in acetone for 30 min., and then collected by filtration and washed with Et.sub.2 O to give 0.700 g of nearly pure product. This material was dissolved in 5-10 mL of methanol, filtered through a plug of cotton, and then diluted with Et.sub.2 O to precipitate a yellow solid. The solid was collected by filtration, washed with Et.sub.2 O, and dried in vacuo to give 0.499 g (49% yield) of 1-[2-hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium chloride as a yellow solid. .sup.1 H NMR (300 MHz, DMSO-d.sub.6) .delta.3.53 (d, J=18 Hz, 1H), 3.75 (d, J=18 Hz, 1H), 3.92-3.93 (m, 8H), 4.38 (d, J=13 Hz, 1H), 4.45 (d, J=13 Hz, 1H), 5.13 (d, J=5 Hz, 1H), 5.50-5.81 (br s, 3H), 5.67 (dd, J=5, 8 Hz, 1H), 7.23 (dd, J=2, 8 Hz, 1 H), 7.44-7.48 (m, 2H), 7.98 (d, J=7 Hz, 2H), 8.85 (d, J=7 Hz, 2H), 9.30 (d, J=8 Hz, 1H); .sup.13 C NMR (75 MHz, DMSO-d.sub.6) .delta.27.2, 33.5, 34.07, 57.49, 59.31, 60.71, 76.40, 122.28, 123.37, 126.15, 126.27, 127.18, 128.81, 130.69, 132.53, 137.88, 141.82, 161.56, 162.98, 164.16, 168.22; IR (KBr) 3290, 1776, 1676, 1624, 1540, 1094 cm.sup.-1 ; FAB MS m/z 646 (MH.sup.+). Anal. Calcd. For C.sub.25 H.sub.25 N.sub.3 O.sub.7 S.sub.3 Cl.sub.2.HCl.0.75 H.sub.2 O: C, 43.11; H, 3.98; N, 6.03. Found: C, 43.31; H, 4.06; N, 5.97.

Following the general procedures shown above, the following thiopyridone derivatives were prepared:

__________________________________________________________________________Compound .sup.1 H NMR DATA MS__________________________________________________________________________ DATA ##STR43## 3.35-3.42(m, 1H), 3.44-3.50(m, 2H), 3.52-3.65(m, 2H), 3.71-3.80(m, 1H), 3.82-3.90(m, 1H), 4.13(dd, J=11, 1, 1H), 4.37(t, J=5, 1H), 4.46 (d, J=6, 1H), 4.54(d, J=5, 1H), 4.59(d, J=6, 1H), 5.16(d, J=5, 1H), 7.13(d, J=7, 2H), 7.51(d, J=7, M+ = 275 ##STR44## 4.09-4.15(m, 2H), 4.32-4.36(m, 2H), 7.53(d, J=7, 2H), 7.82(d, J=7, 2H) MH = 234 ##STR45## 3.98, (t, J=5, 2H), 4.16(t, J=5, 2H), 7.13(d, J=7, 2H), 7.57(d, J=7, 2H) MH = 234__________________________________________________________________________

The following compounds were prepared according to the general procedures of Examples 1 and 2 by varying the thiol starting material and the pyridine or thiopyridone derivative: ##STR46##

__________________________________________________________________________Ex. No. Ar R.sup.1 R.sup.2 R.sup.3 Isolated__________________________________________________________________________ As 3 2,4,5-trichlorophenyl CH.sub.3 H H HCl salt 4 2,6-dichloropyridin-4-yl CH.sub.3 H H HI salt 5 2,4,5-trichlorophenyl CH.sub.2 CH.dbd.CH.sub.2 H H CF.sub.3 CO.sub.2 H salt 6 2,5-dichlorophenyl CH.sub.2 CONH.sub.2 H H CF.sub.3 CO.sub.2 H salt 7 2,4,5-trichlorophenyl CH.sub.2 CONH.sub.2 H H HCl salt 8 2,6-dichloropyridin-4-yl CH.sub.2 CONH.sub.2 H H HI salt 9 3-bromophenyl CH.sub.2 CONH.sub.2 H H HCl salt10 2-chloro-5-trifluoromethylphenyl CH.sub.2 CONH.sub.2 H H HCl salt11 1-naphthyl CH.sub.2 CONH.sub.2 H H HCl salt12 2-benzthiazolyl CH.sub.2 CONH.sub.2 H H HCl salt13 3,5,6-trichloropyridin-2-yl CH.sub.2 CONH.sub.2 H H HI salt14 2,4,5-trichlorophenyl CH.sub.2 C(O)CH.sub.3 H H HI salt15 2,5-dichlorophenyl CH.sub.2 CH.sub.2 OH H H HCl salt16 2,6-dichloropyridin-4-yl CH.sub.2 CH.sub.2 OH H H HCl salt17 2,5-dichlorophenyl CH.sub.2 CH.sub.2 CH.sub.2 OH H H HCl salt18 2,5-dichlorophenyl CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 OH H H HCl salt19 2,5-dichlorophenyl CH(CH.sub.2 OH).sub.2 H H HCl salt20 2,5-dichlorophenyl CH.sub.2 CON(CH.sub.2 CH.sub.2 OH).sub.2 H H HCl salt21 2,5-dichlorophenyl CH.sub.2 CONHCH(CH.sub.2 OH).sub.2 H H HI salt22 2,5-dichlorophenyl H H HBr salt23 2,5-dichlorophenyl ##STR47## H H CF.sub.3 CO.sub.2 H salt24 2,5-dichlorophenyl ##STR48## H H HCl salt25 2,5-dichlorophenyl ##STR49## H H HCl salt26 2,5-dichlorophenyl CH.sub.2 CH.sub.2 OPO.sub.3 H.sub.2 H H diNa salt27 2,6-dichloropyridin-4-yl CH.sub.2 CH.sub.2 OPO.sub.3 H.sub.2 H H diNa salt28 2,5-dichlorophenyl CH.sub.2 CH.sub.2 OSO.sub.3 H H H HCl salt29 2,6-dichloropyridin-4-yl CH.sub.2 CH.sub.2 OSO.sub.3 H H H HCl salt30 2,5-dichlorophenyl ##STR50## H H HCl salt31 2,5-dichlorophenyl ##STR51## H H HCl salt32 2,5-dichlorophenyl CH.sub.2 CH.sub.2 OH 2,6-dimethyl HCl salt33 2,5-dichlorophenyl ##STR52## H H HCl salt34 2,5-dichlorophenyl ##STR53## H H HCl salt35 2,5-dichlorophenyl ##STR54## H H HCl salt36 2,5-dichlorophenyl CH.sub.3 H NHCOCH.sub.2 NH.sub.2 zwitterion__________________________________________________________________________

The .sup.1 H NMR and FAB MS characterizing properties for the compounds of Examples 1-35 are shown below in Table I and II.

TABLE I______________________________________MS DATA MethodEx. No. MS for IV to I______________________________________ 1 MH.sup.+ = 556 1 3 M.sup.+ = 590 1 4 M.sup.+ = 556 1 5 M.sup.+ = 616 1 6 MH.sup.+ =599 1 7 M.sup.+ = 633 1 8 M.sup.+ = 600 1 9 MH.sup.+ = 609 110 MH.sup.+ = 633 111 MH.sup.+ = 582 112 M.sup.+ = 588 113 MH.sup.+ = 634 114 MH.sup.+ = 632 115 MH.sup.+ = 586 216 M.sup.+ = 587 217 MH.sup.+ = 600 218 MH.sup.+ = 614 219 MH.sup.+ = 616 22 MH.sup.+ = 646 220 M.sup.+ = 687 121 MH.sup.+ = 673 122 M.sup.+ = 761 123 MH.sup.+ = 761 124 M.sup.+ = 706 225 M.sup.+ = 662 226 (M.sup.+ + Na) = 688 227 M.sup.+ = 666 228 (MH.sup.+ - SO.sub.3) = 586 229 (M.sup.+ - H) = 665 230 M.sup.+ = 678 231 M.sup.+ = 646 232 MH.sup.+ = 614 233 M.sup.+ = 663 234 MH.sup.+ = 692 235 M.sup.+ = 772 236 MH.sup.+ = 628 1______________________________________ TABLE 2 - NMR DATA ##STR55## C pd. of Ex. No. H-2 H-6 H-7 H-3' H-7' NH ArH SPyrH R 1 3.49(d, J=18) 5.13(d, J=5) 5.68(dd, J=5, 8) 4.37(s) 3.91(s) 9.28(d, J=8) 7.23(dd, J=2, 8) 7.98(d, J=7) 4.17(s) 3.73(d, J=18) 7.46-7.49(m) 8.70(d, J=7) 3 3.48(d, J=18) 5.12(d, J=5) 5.66(dd, J=5, 8) 4.36(d, J=14) 3.94(s) 9.28(d, J=8) 7.67(s) 7.99(d, J=7) 4.17(s) 3.73(d, J=18) 4.40(d, J=14) 7.85(s) 8.69(d, J=7) 4 3.48(d, J=18) 5.13(d, J=5) 5.68(dd, J=5, 8) 4.38(t, J=13) 4.00(s) 9.29(d, J=8) 7.51(s) 7.98(d, J=7) 4.17(s) 3.74(d, J=18) 8.68(d, J=7) 5 3.50(d, J=18) 5.13(d, J=5) 5.68(dd, J=5, 8) 4.38(br s) 3.93(s) 9.25(d, J=8) 7.66(s) 8.02(d, J=6) 5.09(d, J=5) 3.74(d, J=18) 7.84(s) 8.71(d, J=6) 5.30-5.42(m) 6.10(m) 6 3.52(d, J=18) 5.14(d, J=5) 5.68(dd, J=5, 8) 4.36(d, J=13) 3.91(s) 9.28(d, J=8) 7.23(dd, J=2, 8) 8.03(d, J=7) 8.01(s) 3.75(d, J=18) 4.44(d, J=13) 7.46-7.49(m) 8.64(d, J=7) 7.66(s) 5.21(s) 7 3.49(d, J=18) 5.09(d, J=5) 5.62(dd, J=5, 8) 4.37(d, J=13) 3.93(s) 9.27(d, J=8) 7.67(s) 8.10(d, J=7) 5.23(s) 3.69(d, J=18) 4.50(d, J=13) 7.84(s) 8.64(d, J=7) 8 3.51(d, J=18) 5.13(d, J=5) 5.68(dd, J=5, 8) 4.35(d, J=10) 3.99(s) 9.29(d, J=8) 7.50(s) 8.03(d, J=7) 5.19(s) 3.74(d, J=18) 4.44(d, J=10) 8.63(d, J=7) 9 3.44(d, J=18) 5.03(d, J=5) 5.54(dd, J=5, 8) 4.32(d, J=13) 3.75(d, J=15) 9.12(d, J=8) 7.22(t, J=8) 8.25(d, J=7) 5.18(s, 2H) 3.61(d, J=18) 4.60(d, J=14) 3.82(d, J=15) 7.29-7.36(m) 8.59(d, J=7) 7.65(s, 1H) 7.54(t, J=2) 7.99(s, 1H) 10 3.52(d, J=18) 5.13(d, J=5) 5.67(dd, J=5, 8) 4.37(d, J=13) 3.98(s) 9.33(d, J=8) 7.52(dd, J=1, 8) 8.04(d, J=7) 5.28(s, 2H) 3.74(d, J=18) 4.44(d, J=13) 7.66-7.69(m) 8.69(d, J=7) 7.78(s, 1H) 8.19(s, 1H) 11 3.51(d, J=18) 5.09(d, J=5) 5.63(dd, J=5, 8) 4.35(d, J=13) 3.83(s) 9.20(d, J=8) 7.45(t, J=8) 8.10(d, J=8) 5.22(s) 3.69(d, J=18) 4.49(d, J=13) 7.58(m) 8.64(d, J=7) 7.64(s) 7.79(d, J=8) 8.08(m) 8.20(m) 8.93(m) 12 3.52(d, J=18) 5.12(d, J=5) 5.69(dd, J=5, 8) 4.35(d, J=13) 4.22(s) 9.35(d, J=8) 7.34(t, J=8) 8.07(d, J=7) 5.24(s) 3.72(d, J=18) 4.46(d, J=13) 7.44(t, J=8) 8.66(d, J=7) 7.65(s) 7.83(d, J=8) 8.12(s) 7.89(d, J=8) 13 3.54(d, J=18) 5.15(d, J=5) 5.70(dd, J=5, 8) 4.36(d, J=13) 4.02(s) 9.25(d, J=8) 8.35(s) 8.02(d, J=7, 5.21(s) 3.76(d, J=18) 4.43(d, J=13) overlaps with R) 8.01(s, overlaps 8.65(d, J=7) with SPyrH) 7.66(s) 14 3.53(d, J=18) 5.14(d, J=5) 5.69(dd, J=5, 8) 4.40(t, J=13) 3.93(s) 9.27(d, J=8) 7.66(s) 8.04(d, J=7) 2.27(s) 3.76(d, J=18) 7.85(s) 8.50(d, J=7) 5.54(s) 15 3.51(d, J=18) 5.14(d, J=5) 5.68(dd, J=5, 8) 4.36(d, J=13) 3.99(s) 9.29(d, J=8) 7.24(dd, J=2, 8) 8.01(d, J=7) 3.78(m) 3.68(d, J=18) 4.42(d, J=13) 7.47(m) 8.72(d, J=7) 4.50(m) 16 3.48(d, J=18) 5.11(d, J=5) 5.65(dd, J=5, 8) 4.35(d, J=13) 3.99(s) 9.30(d, J=8) 7.50(s) 8.02(d, J=7) 3.78(m) 3.72(d, J=18) 4.42(d, J=13) 8.69(d, J=7) 4.48(m) 17 3.50(d, J=18) 5.12(d, J=5) 5.67(dd, J=5, 8) 4.37(t, J=13) 3.92(s) 9.31(d, J=8) 7.22(dd, J=2, 8) 7.99(d, J=7) 2.00(m) 3.74(d, J=18) 7.43-7.47(m) 8.81(d, J=7) 3.41(m) 4.52(t, J=7) 18 3.50(d, J=18) 5.12(d, J=5) 5.67(dd, J=5, 8) 4.38(t, J=13) 3.92(s) 9.31(d, J=8) 7.22(dd, J=2, 8) 8.01(d, J=7) 1.38(m) 3.74(d, J=18) 7.43-7.47(m) 8.84(d, J=7) 1.88(m) 3.39(t, J=6) 4.47(t, J=7) 19 3.54(d, J=18) 5.15(d, J=5) 5.69(dd, J=5, 8) 4.38(d, J=13) 3.92(s) 9.31(d, J=8) 7.23(dd, J=2, 8) 8.03(d, J=7) 3.84(br s) 3.76(d, J=18) 4.45(d, J=13) 7.44-7.47(m) 8.81(d, J=7) 4.67-4.77(m) 5.43(br s) 2 3.53(d, J=18) 5.13(d, J=5) 5.67(dd, J=5, 8, 4.38(d, J=13) 3.92-3.93(m, 9.30(d, J=8) 7.23(dd, J=2, 8) 7.98(d, J=7) 3.92-3.93(m, 3.75(d, J=17) overlaps with R) 4.45(d, J=13) overlaps with R) 7.44-7.48(m) 8.85(d, J=7) overlaps with H-7') 5.50-5.81(br s, overlaps with H-7) 20 3.61(d, J=18) 5.15(d, J=5) 5.71-5.67(m, 4.38(d, J=13) 3.92(s) 9.29(d, J=8) 7.24(dd, J=2, 8) 8.04(d, J=7) 3.01(br s) 3.77(d, J=18) overlaps with R) 4.44(d, J=13) 7.46-7.49(m) 8.64(d, J=7) 3.27(br s) 3.36(m) 3.49(m) 3.63(m) 5.67(s, overlaps with H-7) 21 3.49(d, J=17) 5.10(d, J=5) 5.63(dd, J=5, 8) 4.37(d, J=13) 3.90(s) 9.26(d, J=8) 7.22(d, J=7) 8.07(d, J=6) 3.43-3.45(m, overlaps with R) 4.48(d, J=13) 7.43-7.46(m) 8.60(d, J=6) overlaps with H-2) 3.70(d, J=17, 3.67-3.72(m, overlaps with R) overlaps with H-2) 4.75(br s) 8.49(d, J=7) 22 3.36-3.50(m, 5.08(d, J=5) 5.61(dd, J=5, 8) 4.40(d, J=13) 3.88(s) 9.25(d, J=8) 7.23(dd, J=2, 8) 8.06(d, J=6) 3.50-3.36(m, overlaps with R) 4.46(d, J=13) 7.45(m) 8.62(br s) overlaps with H-2) 3.67(s) 4.66(t, J=9) 5.26(br s) 9.39(d, J=8) 23 3.45(d, J=18) 5.05(d, J=5) 5.32(m) 3.92(d, J=15) 3.90(s) 9.28(d, J=8) 7.23-7.19(m) 8.05(d, J=7, 3.67-3.42(m) 3.65(d, J=18) 5.59(dd, J=5, 8) 4.01(d, J=15) 7.51-7.43(m) from one anomer) 4.23-4.44(m) 7.98(d, J=7, 4.95(s), 5.16 (s) from one anomer) 4.95(br s), 6.64(s) 8.50-8.60(m) 9.48(d, J=8) 24 3.50-3.70(m, 5.13(d, J=5) 5.69(dd, J=5, 8) 4.37(br s) 3.91(br s) 9.28(d, J=8) 7.23(dd, J=2, 8) 7.97(d, J=7) 3.40-3.80(m, overlaps with R) 7.45(d, J=8) 8.68(d, J=7) overlaps with H-2) 7.47(d, J=2) 4.35(d, J=11) 4.67(d, J=11) 25 3.47(d, J=18) 5.13(d, J=5) 5.69(dd, J=5, 8) 4.37(m) 3.94(s) 9.27(d, J=8) 7.24(m) 8.00(d, J=7) 3.18(m) 3.73(d, J=18) 7.47(m) 8.65(d, J=7) 4.62(m) 6.68(d, J=7) 6.98(d, J=7) 26 3.28(d, J=18) 4.95(d, J=5) 5.46(d, J=5) 4.07(d, J=14) 3.76(d, J=16) Exchanged 7.16(dd, J=2, 8) 7.73(d, J=7) 4.09(m) 3.56(d, J=18) 4.32(d, J=14) 3.85(d, J=16) (D.sub.2 O) 7.29(d, J=2) 8.42(d, J=7) 4.55(m) 7.32-7.35(m) 27 3.35(d, J=18) 4.99(d, J=5) 5.50(d, J=5) 4.16(d, J=13) 3.93(d, J=10) Exchanged 7.29(d, J=2) 7.74(d, J=7) 4.08(m) 3.60(d, J=18) 4.33(d, J=13) 3.98(d, J=10) (D.sub.2 O) 8.43(d, J=7) 4.54(m) 28 3.52(d, J=18) 5.13(d, J=5) 5.69(dd, J=5, 8) 4.34(d, J=13) 3.90(s) 9.27(d, J=8) 7.23(dd, J=2, 8) 8.00(d, J=7) 4.16(m) 3.74(d, J=18) 4.40(d, J=13) 7.43-7.46(m) 8.71(d, J=7) 4.63(m) 29 3.52(d, J=18) 5.13(d, J=5) 5.68(dd, J=5, 8) 4.34(d, J=13) 3.99(s) 9.29(d, J=8) 7.49(s) 8.00(d, J=7) 4.16(m) 3.74(d, J=18) 4.40(d, J=13) 8.70(d, J=7) 4.64(m) 30 3.49(d, J=18) 5.13(d, J=5) 5.69(dd, J=5, 8) 4.36(br, s) 3.94(s) 9.30(d, J=8) 7.28-7.30(m) 8.00(d, J=7) 3.04(m) 3.71(d, J=18) 7.41-7.44(m) 8.63(d, J=7) 4.49(m) 6.62-6.65(m) 31 3.52(d, J=18) 5.13(d, J=5) 5.66(dd, J=5, 8) 4.38(br, s) 3.92(s) 9.30(d, J=8) 7.18-7.29(m, 8.00(d, J=7) 3.22(t, J=8) 3.61(d, J=18) overlaps with R) 8.66(d, J=7) 4.70(t, J=8) 7.45-7.51(m) 7.18-7.29(m, overlaps with ArH) 32 3.50(d, J=18) 5.13(d, J=5) 5.67(dd, J=5, 8) 4.33(d, J=13) 3.92(s) 9.31(d, J=8) 7.22(dd, J=2, 8) 2.75(s, PyrCH.sub.3) 3.69(m) 3.74(d, J=18) 4.39(d, J=13) 7.45(d, J=8) 7.79(s) 4.48(m) 7.47(d, J=2) 33 3.49(d, J=18) 5.13(d, J=5) 5.68(dd, J=5, 8) 4.38(br s) 39.2(s) 9.28(d, J=8) 7.24(dd, J=2, 8) 8.00(d, J=7) 3.08(m) 3.73(d, J=18) 7.49(m) 8.65(d, J=7) 7.00(m) 9.62(m) 34 3.45(s) 5.12(d, J=5) 5.67(m) 4.37(s) 3.93(s) 9.33(d, J=8) 7.23(dd, J=2, 8) 7.98(d, J=6) 3.06(t, J=7) 3.51(s) 7.46(d, J=8) 8.71(d, J=6) 3.70(s, 3H) 7.47(d, J=2) 4.67(t, J=7) 6.51(dd, J=2, 8) 6.67(d, J=8) 6.81(d, J=2) 35 3.42(d, J=18) 5.08(d, J=5) 5.62(dd, J=5, 8) 4.40(br s) 3.92(s) 9.28(d, J=8) 7.23(dd, J=2, 8) 8.06(d, J=7) 3.09(m) 3.65(d, J=18) 7.45-7.50(m) 8.64(d, J=7) 3.69(s) 4.63(m) 6.44(s) 36 3.33(d, J=17) 5.00(d, J=5) 5.54(dd, J=5, 8) 4.39(br s) 3.90(s) 9.19(d, J=8) 7.23(dd, J=2, 9) 8.22(d, J=6) 4.19(s) 3.56(d, J=17) 7.45-7.48(m) 8.53(d, J=6) 8.88(d, J=6) 3.80(s, NHCOCH.sub.2 NH.sub.2)

Claims

1. A compound having the formula ##STR56## wherein Ar is an aryl group selected from the group consisting of ##STR57## in which R.sup.4, R.sup.5, and R.sup.6 are each independently hydrogen, halogen, trihalomethyl, nitro, C.sub.1 -C.sub.6 alkyl, --(CH.sub.2).sub.n OR.sup.7 or --(CH.sub.2).sub.n SR.sup.7 ; n is an integer of from 1 to 6; R.sup.7 is hydrogen or C.sub.1 -C.sub.6 alkyl; R.sup.1 is selected from the group consisting of --CR.sup.8 R.sup.9 R.sup.10, --(CH.sub.2).sub.n CONR.sup.8 R.sup.9 and --(CH.sub.2).sub.n COR.sup.8 in which R.sup.8, R.sup.9 and R.sup.10 are each independently hydrogen, substituted or unsubstituted C.sub.1 -C.sub.15 alkyl, C.sub.2 -C.sub.15 alkenyl or C.sub.2 -C.sub.15 alkynyl, substituted or unsubstituted phenyl, phenyl(C.sub.1 -C.sub.6)alkyl, naphthyl or naphthyl(C.sub.1 -C.sub.6)alkyl or a sugar moiety of the formula ##STR58## in which said alkyl, alkenyl or alkynyl group, or the alkyl portion of said phenyl(C.sub.1 -C.sub.6)alkyl or naphthyl(C.sub.1 -C.sub.6)alkyl group can be substituted by one or more hydroxy groups and said phenyl or naphthyl group, or the phenyl or naphthyl portion of said phenyl(C.sub.1 -C.sub.6)alkyl or naphthyl(C.sub.1 -C.sub.6)alkyl group can be substituted by one or more hydroxy, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, halo or halo(C.sub.1 -C.sub.6)alkyl groups; n is as defined above; R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl, or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; and R.sup.11 is hydrogen, an anionic charge or a carboxyl-protecting group, provided that when R.sup.11 is hydrogen or a protecting group, there is also present a counter ion; or a pharmaceutically acceptable salt or prodrug thereof.

2. A compound of claim 1 wherein Ar is ##STR59## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

3. A compound having the formula ##STR60## wherein Ar is an aryl group selected from the group consisting of ##STR61## in which R.sup.4, R.sup.5, and R.sup.6 are each independently hydrogen, halogen, trihalomethyl, nitro, C.sub.1 -C.sub.6 alkyl, --(CH.sub.2).sub.n OR.sup.7 or --(CH.sub.2).sub.n SR.sup.7 ; n is an integer of from 1 to 6; R.sup.7 is hydrogen or C.sub.1 -C.sub.6 alkyl; R.sup.1 is --CR.sup.8 R.sup.9 R.sup.10 in which R.sup.8, R.sup.9 and R.sup.10 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl, hydroxy(C.sub.1 -C.sub.6)alkyl, C.sub.2 -C.sub.6 alkenyl, phenyl(C.sub.1 -C.sub.6)alkyl, hydroxyphenyl(C.sub.1 -C.sub.6)alkyl or dihydroxyphenyl(C.sub.1 -C.sub.6)alkyl; R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino (C.sub.1 -C.sub.6)alkylcarbonylamino; and R.sup.11 is hydrogen, an anionic charge or a carboxyl-protecting group, provided that when R.sup.11 is hydrogen or a protecting group, there is also present a counter ion; or a pharmaceutically acceptable salt or prodrug thereof.

4. A compound of claim 3 wherein Ar is ##STR62## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

5. A compound having the formula ##STR63## wherein Ar is an aryl group selected from the group consisting of ##STR64## in which R.sup.4, R.sup.5, and R.sup.6 are each independently hydrogen, halogen, trihalomethyl, nitro, C.sub.1 -C.sub.6 alkyl, --(CH.sub.2).sub.n OR.sup.7 or --(CH.sub.2).sub.n SR.sup.7 ; n is an integer of from 1 to 6; R.sup.7 is hydrogen or C.sub.1 -C.sub.6 alkyl; R.sup.1 is --(CH.sub.2).sub.n CONR.sup.8 R.sup.9 in which R.sup.8 and R.sup.9 are each independently hydrogen, hydroxy (C.sub.1 -C.sub.6)alkyl, ##STR65## n is as defined above; R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino (C.sub.1 -C.sub.6)alkylcarbonylamino; and R.sup.11 is hydrogen or a protecting group, provided that when R.sup.11 is hydrogen or a protecting group, there is also present a counter ion; or a pharmaceutically acceptable salt or prodrug thereof.

6. A compound of claim 5 wherein R.sup.1 is ##STR66##

7. A compound having the formula ##STR67## wherein Ar is an aryl group selected from the group consisting of ##STR68## in which R.sup.4, R.sup.5, and R.sup.6 are each independently hydrogen, halogen, trihalomethyl, nitro, C.sub.1 -C.sub.6 alkyl, --(CH.sub.2).sub.n OR.sup.7 or --(CH.sub.2).sub.n SR.sup.7 ; n is an integer of from 1 to 6; R.sup.7 is hydrogen or C.sub.1 -C.sub.6 alkyl; R.sup.1 is --(CH.sub.2).sub.n COR.sup.8 in which R.sup.8 is C.sub.1 -C.sub.6 alkyl; n is as defined above; R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; and R.sup.11 is hydrogen, an anionic charge or a carboxyl-protecting group, provided that when R.sup.11 is hydrogen or a protecting group, there is also present a counter ion; or a pharmaceutically acceptable salt or prodrug thereof.

8. A compound of claim 7 wherein Ar is ##STR69## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

9. A compound having the formula ##STR70## wherein Ar is an aryl group selected from the group consisting of ##STR71## in which R.sup.4, R.sup.5, and R.sup.6 are each independently hydrogen, halogen, trihalomethyl, nitro, C.sub.1 -C.sub.6 alkyl, --(CH.sub.2).sub.n OR.sup.7 or --(CH.sub.2).sub.n SR.sup.7 ; n is an integer of from 1 to 6; R.sup.7 is hydrogen or C.sub.1 -C.sub.6 alkyl; R.sup.1 is ##STR72## R.sup.2 and R.sup.3 are each independently hydrogen, C.sub.1 -C.sub.6 alkyl or amino(C.sub.1 -C.sub.6)alkylcarbonylamino; and R.sup.11 is hydrogen or a protecting group, provided that when R.sup.11 is hydrogen or a protecting group, there is also present a counter ion; or a pharmaceutically acceptable salt or prodrug thereof.

10. A compound of claim 9 wherein Ar is ##STR73## in which R.sup.4, R.sup.5 and R.sup.6 are each independently hydrogen, halogen, trifluoromethyl or C.sub.1 -C.sub.6 alkyl.

11. A compound selected from the group consisting of

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(1-Prop-2-enyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]-methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3-bromophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-chloro-5-trifluoromethylphenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(1-naphthylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-benzthiazolylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3,5,6-trichloropyridin-2-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Acetylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(3-Hydroxy-1-propyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(4-Hydroxy-1-butyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-Hydroxy-1-(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-Hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[(N,N-di-2-Hydroxyethyl)carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-[2-Hydroxy-1-(hydroxymethyl)ethyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-2-[2-Deoxy-D-galactopyranosyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-3-(3-Deoxy-D-glucopyranosyl)carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[1-(1-Deoxy-D-glucitolyl)]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-(4-Hydroxyphenyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Phosphorylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-(3,4-Dihydroxyphenyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-Phenylethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof; and

1-Methyl-3-amino methylcarbonylamino-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl)methylthio)]pyridinium inner salt or a pharmaceutically acceptable salt thereof.

12. A compound selected from the group consisting of

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]-methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3-bromophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-chloro-5-trifluoro-methylphenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(1-naphthylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2-benzthiazolylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Acetylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,4,5-trichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Hydroxy-1-ethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(3-Hydroxy-1-propyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenyl-thio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]-pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(4-Hydroxy-1-butyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-Hydroxy-1-(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-Hydroxy-1,1-di(hydroxymethyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[(N,N-di-2-Hydroxyethyl)carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-[2-Hydroxy-1-(hydroxymethyl)ethyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-2-[2-Deoxy-D-galactopyranosyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[1-(1-Deoxy-D-glucitolyl)]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichloro-phenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[2-(4-Hydroxyphenyl)ethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof; and

1-Methyl-3-aminomethylcarbonylamino-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl)methylthio)]pyridinium inner salt or a pharmaceutically acceptable salt thereof.

13. A compound selected from the group consisting of

1-Methyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-Carbamoylmethyl-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(3-bromophenylthio)-acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-[2-Hydroxy-1-(hydroxymethyl)ethyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo-[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[N-2-[2-Deoxy-D-galactopyranosyl]carbamoylmethyl]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof

1-[1-(1-Deoxy-D-glucitolyl)]-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,5-dichlorophenylthio)acetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methylthio]pyridinium inner salt or a pharmaceutically acceptable salt thereof; and

1-(2-Sulfonylhydroxyethyl)-4-[[(6R)-trans-2-carboxy-8-oxo-7-[(2,6-dichloropyridin-4-yl)thioacetamido]-5-thia-1-azabicyclo[4.2.0]-oct-2-en-3-yl]methyl-thio]pyridinium inner salt or a pharmaceutically acceptable salt thereof.

14. A pharmaceutical composition comprising an effective antibacterial amount of a compound of claim 1 and a pharmaceutically acceptable carrier or diluent.

15. A method of treating a bacterial infection which comprises administering to a host afflicted with such infection an effective antibacterial amount of a compound of claim 1.

16. A method of treating a bacterial infection caused by a strain of methicillin-resistant Staphylococcus aureus which comprises administering to a host afflicted with such infection an effective antibacterial amount of a compound of claim 1.