6-(SUBSTITUTED) METHYLENEPENICILLANIC AND 6-(SUBSTITUTED) HYDROXYMETHYLPENICILLANIC ACIDS AND DERIVATIVES THEREOF

Abstract: Beta-lactamase inhibiting compounds of the formula or a pharmaceutically acceptable acid addition or carboxylate salt thereof; where n is zero, 1 or 2; X₃ is H or Br, R¹ is H, the residue of certain carboxy-protecting groups or the residue of an ester group readily hydrolyzable in vivo; one of R¹² and R¹³ is H and the other is vinyl, certain aryl, arythio, alkylthio, alkyl­ sulfonyl or certain heterocyclyl, aminomethyl, thiocarbox­ amido or amidino groups; one of R² and R³ is H and the other is as diclosed for the other of R¹² and R¹³, or is Cl or CH₂OH, and R¹⁸ is H or certain acyl groups; intermediates useful in their production, methods for their preparation and use, and pharmaceutical compositions containing them.

Description: The invention relates to novel 6-(substituted) methylenepenicillanic acids, and novel 6-(substituted)hydroxymethylpenicillanic acids, certain esters and pharmaceutically acceptable salts thereof, pharmaceutical compositions containing them, methods for their preparation and their use as beta-lactamase inhibitors and intermediates therefor. One of the most well-known and widely used of the classes of antibacterial agents is the class known as the beta-lactam antibiotics. These compounds are characterized in that they have a nucleus consisting of a 2-azetidinone (beta-lactam) ring fused to either a thiazolidine or a dihydro-1,3-thiazine ring. When the nucleus contains a thiazolidine ring, the compounds are usually referred to generically as penicillins, whereas when the nucleus contains a dihydrothiazine ring, the compounds are referred to as cephalosporins. Typical examples of penicillins which are commonly used in clinical practice are benzylpenicillin (penicillin G), phenoxymethylpenicillin (penicillin V), ampicillin and carbenicillin; typical examples of common cephalosporins are cephalothin, cephalexin and cefazolin. However, despite the wide use and wide acceptance of the beta-lactam antibiotics as valuable chemotherapeutic agents, they suffer from the major drawback that certain members are not active against certain microorganism. It is thought that in many instances this resistance of a particular microorganism to a given beta-lactam antibiotic results because the microorganism produces a beta-lactamase. The latter substances are enzymes which cleave the beta-lactam ring of penicillins and cephalosporins to give products which are devoid of antibacterial activity. However, certain substances have the ability to inhibit beta-lactamases, and when a beta-lactamase inhibitor is used in combination with a penicillin or cephalosporin it can increase or enhance the antibacterial effectiveness of the penicillin or cephalosporin against certain microorganisms. It is considered that there is an enhancement of antibacterial effectiveness when the antibacterial activity of a combination of a beta-lactamase inhibiting substance and a beta-lactam antibiotic is significantly greater than the sum of the antibacterial activities of the individual components. Thus, according to the invention, there are provided new compounds which are 6-(substituted)methylenepencillanic acids, their 1-oxides, 1,1-dioxides and esters thereof readily hydrolyzable in vivo . These new penicillanic acids and their esters readily hydrolyzable in vivo are potent inhibitors of microbial beta-lactamases. Accordingly, there is also provided a method for enhancing the effectiveness of beta-lactam antibiotics, using these novel acids, their salts and certain readily hydrolyzable esters thereof. Still further, there are provided derivatives of 6-(substituted)methylenepenicillanic acids, their 1-oxides and 1,1-dioxides having a carboxy protecting group, said compounds being useful as chemical intermediates. Yet further, there are provided 6-(substituted)hydroxymethylpenicillanic acids, their 1-oxides, 1,1-dioxides and salts and esters thereof which are useful both as chemical intermediates and as beta-lactamase inhibitors. European Patent Application No. 50,805 discloses compounds of the formula wherein n is zero, 1 or 2, R₁ is CN or certain carbonyl moieties; R₂ is hydrogen, lower alkyl or halogen and R₃ is hydrogen or a readily hydrolyzable group, useful as beta-lactamase inhibitors. The same reference discloses 6-oxopenicillanic acid esters, the corresponding sulfoxides and sulfones as well as a method for their use in preparation of compounds of formula (III) by reaction with a phosphoran of formula R₁R₂C = P(C₆H₅)₃. United Kingdom Patent Application GB 2,053,220A discloses, inter alia , certain 6-methylene-1,1-dioxopenicillanic acids and esters of the above formula (III) where n is 2 and R₁ and R₂ independently denote hydrogen, an optionally substituted alkyl, aryl, optionally substituted cycloalkyl, an aralkyl or optionally substituted amino group, or together with the carbon atom to which they are attached, R₁ and R₂ form a 3 to 7-membered carbocyclic or heterocyclic ring. U.S. 4,287,181 discloses certain 6-substituted penicillanic acid 1,1-dioxides and esters thereof wherein the 6-substituent is and, inter alia , R₃ is H or alkanoyl and R₄ is H, (C₁-C₄)alkyl, phenyl, benzyl or pyridyl, which are useful as beta-lactamase inhibitors. European Patent Application 18305 claims, as intermediates for making β- lactamase inhibitors, compounds of formula where Ra² and Ra³ are aryl, hydrogen, halogen, amine or substituted amine or an unsubstituted or substituted straight or branched chain aliphatic group, R is a free or esterified carboxyl group, and R⁸ is derived from an organometallic reagent. The present invention provides novel 6-(substituted)methylenepenicillanates of the formula wherein n is zero, 1 or 2; R¹ is R a or R b where R a is the residue of a carboxy protecting group selected from tetrahydropyranyl, allyl, benzyl, 4-nitrobenzyl, benzhydryl, 2,2,2-trichloroethyl, t -butyl and phenacyl; and R b is hydrogen or the residue of an ester group readily hydrolyzable in vivo selected from 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, and R⁴ and R⁵ are each hydrogen or CH₃, R⁶ is (C₁-C₅)alkyl, and R¹⁴ is where X₂ is the 3-substituent of a known cephalosporin beta-lactam antibiotic and R¹⁵ is the 6- or 7-substituent, respectively, of a known penicillin or cephalosporin beta-lactam antibiotic. Especially preferred R¹⁴ are the above penicillin residues wherein R¹⁵ is 2-phenylacetamido, 2-phenoxyacetamido, D-2-amino-2-phenylacetamido, D-2-amino-2-(4-hydroxyphenyl)acetamido, 2-carboxy-2-phenylacetamido, 2-carboxy-2-(2-thienyl)acetamido, 2-carboxy-2-(3-thienylacetamido, D-2-(4-ethyl-2,3-dioxopiperazinocarbonylamino)-2-phenylacetamido, D-2-(4-ethyl-2,3-dioxopiperazinocarbonylamino)-2-(4-hydroxyphenyl)acetamido or 2,2-dimethyl-4-phenyl-5-imidazolidinone-1-yl; one of R² and R³ is hydrogen and the other is CH₂OH, vinyl, (C₁-C₄)alkylthio, (C₁-C₄)alkylsulfonyl, furyl, thienyl, N-methylpyrrolyl, N-acetylpyrrolyl, R⁷C₆H₄, R⁷C₆H₄S, -CH(R⁴)NR¹⁶R¹⁷, and m is 2 or 3, p is zero or 1, t is zero, 1 or 2, X₁ is S, O or NR¹¹, R⁷ is hydrogen, (C₁-C₄)alkyl, (C₁-C₄)alkoxy, allyloxy, hydroxyl, carboxyl, (C₂-C₅)alkoxycarbonyl, (C₁-C₅)alkylcarbonyl, phenyl, benzyl, naphthyl, pyridyl, NR⁸R⁹, CONR⁸R⁹, NHCOR¹⁰, NO₂, Cl, Br, CF₃ or SR⁸; R⁸ and R⁹ are each hydrogen, (C₁-C₄)alkyl, phenyl or benzyl; R¹⁰ is (C₁-C₄)alkyl, CF₃ or phenyl; R¹¹ is hydrogen, CH₃, C₂H₅ or CH₃CO; R¹⁶ and R¹⁷ are each H, (C₁-C₄)alkyl, (C₂-C₄)hydroxyalkyl, or taken together with the nitrogen atom to which they are attached R¹⁶ and R¹⁷ form a 5- to 7-membered heterocyclic group, especially preferred such heterocyclic groups are pyrrolidino, piperidino, morpholino, thiomorpholino, or 4-methylpiperazino; or a pharmaceutically acceptable acid addition salt of said compound where R² or R³ is a group which contains a basic nitrogen atom, or a pharmaceutically acceptable cationic salt of said compound wherein R¹ is hydrogen or R² or R³ contains a carboxy group. The above compounds wherein R¹ is R a are useful as intermediates for preparation of the compounds wherein R¹ is R b . The latter compounds are the active beta-lactamase inhibitors of the invention. The invention further provides 6-(R¹²R¹³-substituted)hydroxymethylpenicillanic acids, 1-oxides, 1,1-dioxides and esters thereof of the formula wherein n and R¹ are as defined above for compounds of formula (I), X₃ is H or Br, one of R¹² and R¹³ is hydrogen and the other is vinyl, (C₁-C₄)alkylsulfonyl, furyl, thienyl, N-methylpyrrolyl, N-acetylpyrrolyl, R⁷C₆H₄, CH(R⁴)NR¹⁶R¹⁷, R¹⁸ is H, (C₂-C₅) alkanoyl, (C₂-C₅) alkoxycarbonyl, pyrazinecarbonyl, benzoyl, CF₃CO or CONR⁸R⁹; and m, p, t, R⁷, R⁸, R⁹, R¹¹, R¹⁶, R¹⁷ and X₁ are as previously defined provided that when R¹² or R¹³ is and p is zero, then R⁷ is other than H or CH₃; provided further than when n is 2, R¹⁸ is H, (C₂-C₅) alkanoyl, (C₂-C₅) alkoxycarbonyl or benzoyl and R¹² or R¹³ is (R⁷) then t is not zero and R⁷ is other than H or CH₃; and provided further that when n is 2, R¹⁸ is H, (C₂-C₅) alkanoyl, (C₂-C₅) alkoxycarbonyl or benzoyl, then R¹² or R¹³ is not provided further that when n=0 and R¹ is hydrogen, allyl, benzyl, benzhydryl or t -butyl, R¹⁸ is hydrogen and one of R¹² and R¹³ is hydrogen then the other of R¹² and R¹³ is not thienyl, furyl, pyridyl, quinolinyl or indolyl, or pyridyl, quinolinyl, pyrrolyl or indolyl substituted by an alkyl group; or a pharmaceutically acceptable acid addition or carboxylate salt thereof. The compounds of formula (II) are all useful as chemical intermediates for preparation of the corresponding 6-(substituted)methylene-1,1-dioxopenicillanates of formula (I). In addition, however, the compounds of formula (II) wherein R¹ is hydrogen or the residue of an ester group readily hydrolyzable in vivo , R b , as defined above, are useful for their beta-lactamase inhibiting activity, especially when used in conjunction with a beta-lactam antibiotic. Particularly preferred compounds of formula (I) are those wherein n is zero or 2 and one of R² and R³ is hydrogen and the other is furyl, thienyl, CH₂OH, phenyl, methylsulfonyl, N-methylpyrrolyl, Particularly preferred compounds of the formula (II) are those wherein n is zero or 2, one of R₁₂ and R₁₃ is H and the other is vinyl, 2-furyl, 2-thienyl, N-methylpyrrol-2-yl, N-acetylpyrrol-2-yl, 3-hydroxy-2-pyridyl, 4-methoxy-2-pyridyl, and R¹⁸ is H or CH₃CO. Particularly preferred values for the carboxy protecting group, R a , are allyl, benzyl, t-butyl and 2,2,2-trichloroethyl and especially preferred is allyl because of the relative ease by which it is selectively prepared and removed. Particularly preferred as the residue of an ester group readily hydrolyzable in vivo , i.e. R b as defined above are and especially those wherein R⁴ and R⁵ are each hydrogen and R⁶ is as previously defined. In addition to providing procedures for making the compounds of formula (I) and (II), the invention further provides a method of treating a bacterial infection in a mammalian subject, including a human, which comprises administering to a mammal in need of such treatment an antibacterially effective amount of a compound of formula (I) wherein R¹ is R b as defined above. Also provided are pharmaceutical compositions for treating a bacterial infection in mammals, including humans, which comprises an antibacterially effective amount of a compound of formula (I) wherein R¹ is R b . The compounds of the formulae (I) and (II) wherein R¹ is R b as defined above are useful as inhibitors of beta-lactamase enzymes. By this mechanism, these compounds enhance the activity of beta-lactam antibiotics (penicillins and cephalosporins), particularly against those microorganisms which are resistant or partially resistant to the beta-lactam antibiotic through the production of enzymes (beta-lactamases) which would otherwise destroy or partially destroy the beta-lactam antibiotic. In this manner, the spectrum of activity of the beta-lactam antibiotic is increased. Still further this invention provides a method of treating a bacterial infection in a mammalian subject, including a human, which comprises administering to a mammal in need of such treatment an antibacterially effective amount of a penicillin or cephalosporin, especially those enumerated below, and a beta-lactamase inhibiting amount of a compound of formula (I) or (II). While the present compounds are effective in enhancing the activity of beta-lactam antibiotics in general, their preferred use is found in their combination with a penicillin or cephalosporin of established clinical utility, viz., amoxicillin, ampicillin, apalcillin, azlocillin, azthreonam, bacampicillin, carbenicillin, carbenicillin indanyl, carbenicillin phenyl, cefaclor, cefadroxil, cefaloram, cefamandole, cefamandole nafate, cefaparole, cefatrizine, cefazolin, cefbuperazone, cefonicid, cefmenoxime, cefodizime, cefoperazone, ceforanide, cefotaxime, cefotiam, cefoxitin, cefpiramide, cefpirome, cefsulodin, ceftazidime, ceftizoxime, ceftriaxone, cefuroxime, cephacetrile, cephalexin, cephaloglycin, cephaloridine, cephalothin, cephapirin, cephradine, cyclacillin, epicillin, furazlocillin, hetacillin, lenampicillin, levopropylcillin, mecillinam, mezlocillin, penicillin G, penicillin V, phenethicillin, piperacillin, pirbenicillin, pivampicillin, sarmoxicillin, sarpicillin, suncillin, talampicillin and ticarcillin, including the pharmaceutically acceptable salts thereof. The names employed for these beta-lactams are generally USAN, i.e., United States Adopted Names. Also included are combinations of the beta-lactamase inhibitors of the invention with 7-[2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-(5,6-dihydro-4-pyrindenium)methyl-3-cephem-4-carboxylate (HR-810); 7-[2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-(N-methylpyrrolidinium)methyl-3-cephem-4-carboxylate (BMY-28,142) and 7-[D-(2-[4-carboxy-5-imidazolcarboxamido])-2-phenylacetamido]-3-[4-(2-sulfonatoethyl)pyridinium]-3-cephem-4-carboxylic acid. Although the compounds of the present invention can be administered separately from the beta-lactam antibiotic, combination dosage forms are preferred. The pharmaceutical composition, whether for oral or parenteral use, comprises in a ratio of 1:3 to 3:1 by weight a beta-lactamase inhibitor of the formula (I) or (II) and a beta-lactam antibiotic, in total amounts sufficient to successfully treat a bacterial infection in a mammal in a single or, more usually, multiple doses. The invention compounds of formulae (I) and (II) wherein one of the groups R², R³, R¹² or R¹³ contain a basic nitrogen atom are capable of forming acid addition salts. Such salts with pharmaceutically acceptable acids are included in the invention. Examples of such acids are hydrochloric, hydrobromic, sulfuric, phosphoric, citric, malic, tartaric, maleic, fumaric, gluconic, saccharic, benzenesulfonic, p -toluenesulfonic, p-chlorobenzenesulfonic and 2-naphthalenesulfonic acids. Further, the compounds of formulae (I) and (II) wherein R¹ is hydrogen form cationic salts and such salts with pharmaceutically acceptable cations are included in the invention. Examples of such cations are sodium, potassium, ammonium, calcium, magnesium, zinc; and substituted ammonium salts formed with amines such as diethanolamine, choline, ethylenediamine, ethanolamine, N-methylglucamine and procaine. This invention relates to derivatives of penicillanic acid which is represented by the following structural formula: In derivatives of penicillanic acid, broken line attachment of a substituent to the bicyclic nucleus indicates that the substituent is below the plane of the nucleus. Such a substituent is said to be in the alpha-configuration. Conversely, broad line attachment of a substituent to the bicyclic nucleus indicates that the substituent is above the plane of the nucleus. This latter configuration is referred to as the beta-configuration. As used herein a solid line attachment (―) of a substituent to the bicyclic nucleus indicates that the substituent can be in either the alpha-configuration or the beta-configuration. The compounds of the invention are prepared for example, by one or more of the following general methods. The requisite Wittig salts of the formula employed in Method A, above, are either known compounds or are readily prepared from commercially available precursors by common synthetic methods, for example as illustrated below. The primary alcohols of the general formula R³CH₂OH are converted to the corresponding chloromethyl compounds, typically by reacting the alcohol with an equimolar amount of thionyl chloride in the presence or a reaction inert solvent, e.g. chloroform or methylene chloride at or about room temperature. The product is isolated, e.g., by neutralization of the reaction mixture and extraction. The chloromethyl compound, R³CH₂Cl is then converted to the desired Wittig salt e.g. by reaction with an equimolar amount of triphenylphosphine. Typically, this step is carried out in a solvent such as toluene at elevated temperature, preferably at the reflux temperature. The desired product forms a precipitate which is then collected by filtration. 6-Alpha-hydroxypenicillanic acid is a known compound, see e.g., Hauser et al., Helv . Chim . Acta , 50 , 1327 (1967). The acid is converted to a carboxy protected derivative of the formula (IV). The identity of the carboxy protecting group is not critical. The only requirements for the carboxy protecting group R a are that: (i) it must be stable to oxidation conditions employed to form the 6-oxopenicillanate ester (V) and its subsequent reaction with the Wittig reagent to form the 6-(substituted)methylenepenicillanate of formula (VI, R¹=R a ); (ii) it must be selectively removable from the compound of formula (VI, R¹=R a ) using conditions under which both the beta-lactam and the 6-(substituted)methylene groups remain substantially intact; (iii) it must be stable to oxidation of the compound (VI, R¹=R a ) to form the sulfones of formula (VII) or the corresponding sulfoxides. Typical such carboxy protecting groups which meet the above requirements are the tetrahydropyranyl group, the benzyl group, the benzhydryl group, the 2,2,2-trichloroethyl group, the allyl group, the t-butyl group and the phenacyl group. See further: United States Patents 3,632,850 and 3,197,466; British Patent No. 1,041,985, Woodward et al., Journal of the American Chemical Society, 88 , 852 (1966); Chauvette, Journal of Organic Chemistry, 36 , 1259 (1971); Sheehan et al., Journal of Organic Chemistry, 29 , 2006 (1964); and "Cephalosporin and Penicillins, Chemistry and Biology", edited by H. E. Flynn, Academic Press, Inc., 1972. Particularly preferred such groups are allyl, benzyl and 2,2,2-trichloroethyl and especially preferred is allyl because of its ease of preparation and selective removal. The oxidation of the carboxy protected 6-alpha-hydroxypenicillanate (IV) to the corresponding 6-oxopenicillanate ester (X) is typically carried out with an approximately equimolar amount of trifluoroacetic anhydride and a molar excess of dimethylsulfoxide in the presence of a reaction inert solvent, e.g., chloroform or methylene chloride. The reaction is preferably carried out at a temperature of from about -80° to -70° C. The reaction mixture is neutralized, e.g. by addition of a tertiary amine such as triethylamine, after which the mixture is isolated, e.g. by partitioning between water and a water immiscible solvent and evaporation of the organic layer. The 6-oxopenicillanate ester of formula (V) is then reacted with a Wittig reagent of formula This reaction is preferably carried out in the presence of a reaction inert organic solvent, for example, a hydrocarbon such as pentane, hexane, benzene, toluene or xylene; a halogenated hydrocarbon such as methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,2-dibromoethane or chlorobenzene; an ether such as tetrahydrofuran, dioxane, diethyl ether, 1,2-dimethoxyethane or t-butylmethylether. While this reaction can be carried out over a range of temperature of from about -100° to +50° C., a preferred temperature is in the range of about -78° to 25° C. The desired product of formula (VI, R¹=R a ) is isolated by known techniques, for example, the reaction is quenched by addition of aqueous ammonium chloride, extraction with a water immiscible solvent and the solvent evaporated. The resulting product is purified, if desired, by conventional methods known to those of skill in the art, for example, by column chromatography on silica gel. The ester of formula (VI, R¹=R a ) where R a is a carboxy protecting group as defined above can then be converted to the corresponding acid or ester of formula (VI, R¹=R b ) where R b is hydrogen or an ester forming residue readily hydrolyzable in vivo . Typically, the carboxy protecting group is removed from the intermediate compound of formula (VI, R¹=R a ) to form the corresponding carboxylic acid. The specific method chosen for removal of the carboxy protecting group will depend upon the precise nature of the ester residue R a , but an appropriate method will be readily recognized to one of skill in the art. As mentioned above, an especially preferred carboxy protecting group, R a , is allyl. While this group can be removed by mild acid or alkaline hydrolyses procedures with satisfactory results, an especially preferred method for its removal employs a soluble palladium (O) complex, tetrakis (triphenylphosphine)palladium (O) as a catalyst, a method previously reported by Jeffrey and McCombie, J . Org . Chem ., 47 , 587-590 (1982). In a typical procedure the allyl ester in reaction inert solvent, e.g. ethylene dichloride, chloroform, ethyl acetate, and a catalytic amount of tetrakis (triphenylphosphine)palladium (O), for example from about 1 to 5 mole percent based on the allyl ester, and an approximately equal weight of triphenylphosphine are combined under a nitrogen atmosphere. To this is added a sodium or potassium salt of 2-ethylhexanoate in an amount equimolar to the starting allyl ester and the resulting mixture is stirred at ambient temperature until precipitation of the desired salt, e.g. of formula (VI) where R¹ is Na or K, is complete. Usually the reaction is substantially complete in from about two to twenty hours. The salt is then collected, e.g. by filtration. When sulfoxides or sulfones of the invention are desired, for example those of the formulae (I) wherein n is 1 or 2, the sulfides of formula (VI) are oxidized employing any of a wide variety of oxidants known in the art for the oxidation of sulfoxides to sulfones. However, particularly convenient reagents are metal permanganates, such as the alkali metal permanganates and the alkaline earth metal permanganates, and organic peroxy acids, such as organic peroxycarboxylic acids. Convenient individual reagents are sodium permanganate, potassium permanganate, 3-chloroperbenzoic acid and peracetic acid. A particularly preferred group of oxidants are the organic peroxy acids and a preferred organic peroxy acid is 3-chloroperbenzoic acid. When the desired oxidation product is a sulfoxide of formula (I) wherein n is 1, approximately molar equivalents of the starting sulfide (n is zero) and oxidant are employed. When the desired product is a sulfone, e.g. of formula (I) where n is 2, the sulfide is contacted with two or more molar equivalents of oxidant. Alternately, of course, the sulfoxides can serve as starting materials for the preparation of the corresponding sulfone, in which case at least an approximately equimolar amount of oxidant is employed. When, for example, a compound of the formula (VI, R¹=R a ), wherein R a is as previously defined, is oxidized to the corresponding compound of the formula (VII), using an organic peroxy acid, e.g., a peroxycarboxylic acid, the reaction is usually carried out by treating the compound of the formula (VI, R¹=R a ) with from about 2 to about 4 molar equivalents of the oxidant in a reaction-inert organic solvent. Typical solvents are chlorinated hydrocarbons, such as dichloromethane, chloroform and 1,2-dichloroethane; and ethers, such as diethyl ether, tetrahydrofuran and 1,2-dimethoxyethane. The reaction is normally carried out at a temperature of from about -20° to about 50° C., and preferably at about 25° C. At about 25° C. reaction times of about 2 to about 16 hours are commonly used. The product is normally isolated by removal of the solvent by evaporation in vacuo . The product can be purified by conventional methods, well-known in the art. In the above-mentioned oxidation procedures it is preferred to employ a starting material wherein the carboxy group is protected by the above-mentioned carboxy protecting groups, R a . The removal of the carboxy protecting group from its product sulfoxide or sulfone is carried out in the normal manner for the particular protecting group being used, for example as described above for the compounds (VI, R¹=R a ). The compounds of the invention, e.g. of formula (I) or (II), wherein R¹ is an ester forming residue readily hydrolyzable in vivo can be prepared directly from the corresponding compound where R¹ is hydrogen, by conventional esterification techniques. The specific method chosen will depend upon the precise structure of the ester forming residue, but an appropriate method will be readily selected by one skilled in the art. In the case where R¹ is selected from 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl and groups of the formulae wherein R⁴, R⁵ and R⁶ are as previously defined, they can be prepared by alkylation of the appropriate invention compound wherein R¹ is hydrogen with a halide of the formula R b Q, that is a 3-phthalidyl halide, a 4-crotonolactonyl halide, a gamma-butyrolacton-4-yl halide or a compound of the formula wherein Q is halo and R⁴, R⁵ and R⁶ are as previously defined. The terms "halide" and "halo" are intended to mean derivatives of chlorine, bromine and iodine. The reaction is typically carried out by dissolving a salt of the compound of e.g., formula (I) or (II) wherein R¹ is hydrogen in a suitable polar organic solvent, for example, N,N-dimethylformamide, and then adding about one molar equivalent of the appropriate halide (R b Q). When the reaction has proceeded essentially to completion, the product is isolated by standard techniques. It is often sufficient simply to dilute the reaction medium with an excess of water, and then extract the product into a water-immiscible organic solvent and then recover same by solvent evaporation. Salts of the starting material which are commonly used are alkali metal salts, such as sodium and potassium salts, tertiary amine salts, such as triethylamine, N -ethylpiperidine, N , N -dimethylaniline and N-methylmorpholine salts and quaternary ammonium salts, such as tetramethylammonium and tetrabutylammonium salts. The reaction is run at a temperature in the range from about 0 to 100° C., and usually at about 25° C. The length of time needed to reach completion varies according to a variety of factors, such as the concentration of the reactants and the reactivity of the reagents. Thus, when considering the halo compound, the iodide reacts faster than the bromide, which in turn reacts faster than the chloride. In fact, it is sometimes advantageous, when utilizing a chloro compound, to add up to one molar equivalent of an alkali metal iodide. This has the effect of speeding up the reaction. With full regard for the foregoing factors, reaction times of from about 1 to about 24 hours are commonly used. When Method B as outlined above is employed to prepare the invention compounds of formula (II) where n is 2 and X₃ and R¹⁸ are each hydrogen or compounds of formula (VIII), the requisite 6-alpha-bromo-1,1-dioxopenicillanate ester starting material (IX) is converted to a Grignard reagent by reaction with an equimolar amount of a low molecular weight Grignard reagent, e.g., methylmagnesium bromide, ethylmagnesium chloride or n-butylmagnesium iodide, in an ethereal solvent, preferably tetrahydrofuran or ethyl ether, at a temperature of from -80 to 25° C., typically -78° C. After stirring for a few minutes, an equimolar amount of the appropriate aldehyde of formula R¹²R¹³C=O is added and stirring continued until the reaction is substantially complete, ordinarily from about 10 minutes to about four hours at the same temperature. The desired ester of formula (II), n = 2, is then isolated by standard methods. For example, the reaction is quenched with aqueous ammonium chloride and the product extracted with a water immiscible solvent. The resulting product, (II), is further purified, e.g., by silica gel chromatography. The secondary alcohol of formula (II), n = 2, X₃ = H, can then be dehydrated to provide the corresponding 6-(substituted)methylene-1,1-dioxopenicillanate compound of formula (VIII). While a variety of methods known in the art for dehydration of secondary alcohols to olefins may be employed to successfully carry out this step, a preferred method employs conversion of the alcohol to an acetate by reaction with at least equimolar amounts of acetic anhydride and pyridine followed by stirring at room temperature for from one to ten hours to allow for formation of olefin in substantial amounts. The reaction is ordinarily quenched with water and the desired product (II), n = 2, is isolated by extraction methods and purified, if desired. The products of formula (II), or (VIII) obtained as described above are esters wherein R¹ is either a carboxy protecting group, R a , as defined above or is the residue of an ester group readily hydrolyzable in vivo , R b , as defined above. These esters wherein R¹ is R a are converted into the corresponding carboxylic acids (R b is hydrogen) by methods described above. Of course, when desired, the carboxylic acids of formula (II) and (VIII) are converted to a corresponding compound wherein R¹ is the residue of an ester group readily hydrolyzable in vivo , by methods also described above. Typically, the starting 6-alpha-bromo-1,1-dioxopenicillanate esters (IX) are prepared from the 6,6-dibromo-1,1-dioxopenicillanic acid by treatment with sodium bicarbonate and sodium bisulfite followed by acidification. The resulting 6-alpha-bromo-1,1-dioxopenicillanic acid is then converted to an ester of formula (IX). The starting esters of formula (X) employed in Method C as outlined above, are known compounds, see, e.g. U.S. 4,234,579. In a typical procedure carried out by this method, the starting ester (X) in reaction inert solvent, e.g. toluene, xylene, pentane, tetrahydrofuran, ethyl ether or mixtures thereof, is contacted at low temperature with an equimolar amount of alkyl lithium reagent, e.g., n -butyl lithium, t -butyl lithium or methyl lithium, to form a lithiopenicillin intermediate. This is immediately contacted with an equimolar amount of aldehyde, R¹²R¹³CO, where R¹²R¹³ are as previously defined, and the fixture stirred at -100 to -50° C., preferable -78° C., for about 1-4 hours. The reaction is then quenched and the bromohydrin intermediate of formula (XI) isolated, for example, by partitioning between water and solvent and purification of the extract by column chromatography on silica gel or Florisil (magnesium silicate). Alternatively, the above starting dibromo ester of formula (X) is reacted with an equimolar amount of a low molecular weight Grignard reagent, employing the same reagents and conditions described above for Method B, to provide the bromohydrin of formula (XI). The bromohydrin (XI) can be acylated to provide the corresponding compound (XII) wherein R¹⁸ is other than hydrogen as defined above. Typically the acylation is carried out by reaction of equimolar amounts of acyl chloride, acyl bromide or the corresponding acid anhydride, the intermediate bromohydrin of formula (XI) and a tertiary amine, for example pyridine, N-methylmorpholine or the like, in the presence of a reaction inert organic solvent, preferably methylene chloride, tetrahydrofuran or ethyl acetate at or below room temperature. The desired diester of formula (XII) is then isolated by well-known methods such as extraction and evaporation of solvent and purified, if desired, e.g. by column chromatography. The bromohydrin ester intermediate (XI) or the bromo diester (XII) can then be subjected to hydrogenolysis conditions to remove the bromine atom. This is accomplished by employing any of a variety of the known reducing agents and conditions such as, e.g. subjecting the bromohydrin to hydrogen in the presence of a noble metal catalyst or to reduction by means of certain organotin hydrides. Preferred organotin hydride reducing agents are the dialkyltin dihydrides, trialkyltin hydrides, having from one to six carbon atoms in each of said alkyl groups, and the triaryltin hydrides wherein said aryl is phenyl, or phenyl substituted by nitro or alkyl or alkoxy having from one to three carbon atoms. Particularly preferred are triphenyltin hydride and tri- n -butyltin hydride, the latter being especially preferred for reasons of economy and efficiency. The reaction employing said tin hydrides is ordinarily carried out in the presence of a reaction inert solvent. Suitable solvents for use with the organotin hydride reducing agents are those which substantially dissolve the starting compound of formula (XI) or (XII) but do not themselves react with the hydride reducing agent. Examples of such solvents include the aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene and napthalene; and ethers such as ethyl ether, isopropyl ether, tetrahydrofuran, dioxane and 1,2-dimethoxyethane. Particularly preferred solvents for reasons of economy and efficiency are benzene and toluene. In carrying out the hydrogenolysis employing organotin hydride reducing agents, equimolar amounts of bromohydrin (XI) or bromodiester (XII) and hydride is required by theory. In practice an excess of hydride, e.g., 5-50% molar excess, is often employed to assure complete reaction. The hydrogenolysis by organotin hydrides proceeds to substantial completion under the preferred conditions disclosed above without use of a catalyst. However, the reaction is expedited by means of a source of free radicals such as, e.g, ultraviolet light, or a catalytic amount of azobisisobutyronitrile or peroxides such as benzoyl peroxide. A catalytic amount of azobisisobutyronitrile is a preferred source of free radicals for this reaction. Typically, the compound of formula (XI) or (XII) is dissolved in reaction inert solvent, the solution is maintained under an inert atmosphere, e.g. a nitrogen or argon atmosphere, and the appropriate amount of organotin hydride and, optionally, the source of free radicals, e.g. azobisisobutyronitrile, added and the resulting mixture stirred at a temperature within the preferred range of from about 0°C. up to the boiling point of the solvent. The reaction is ordinarily complete in from a few minutes to about a few hours, e.g., from 5 minutes at the boiling point of benzene to about 20 hours at 0°C. The product of formula (II, X₃ = H) is then isolated by methods known to those of skill in the art. For example, by evaporation of solvent and silica gel chromatography of the residue. The compounds of formula (II, X₃ = H) formed by organotin hydride debromination as described above, have been found to be predominantly the 6-beta isomers, that is, the 6-R¹²R¹³C(OR¹⁸) substituent is in the beta-configuration. When the hydrogenolysis step is carried out employing hydrogen in the presence of a noble metal catalyst, a convenient method for carrying out this transformation is to stir or shake a solution of a compound of the formula (XI) or (XII) under an atmosphere of hydrogen, or hydrogen mixed with an inert diluent such as nitrogen or argon, in the presence of a noble metal hydrogenolysis catalyst. Suitable solvents for this hydrogenolysis reaction are those which substantially dissolve the starting compound of the formula (XI) or (XII) but which do not themselves suffer hydrogenation or hydrogenolysis. Examples of such solvents include ethers such as diethyl ether, tetrahydrofuran, dioxane and 1,2-dimethoxyethane; low molecular weight esters such as ethyl acetate and butyl acetate; tertiary amides such as N , N -dimethylformamide, N , N -dimethylacetamide and N -methylpyrrolidone; water; and mixtures thereof. Additionally, it is often desirable to buffer the reaction mixture so as to operate at a pH in the range from about 4 to 9, and preferably from about 6 to 8. Borate, bicarbonate and phosphate buffers are commonly used. Introduction of the hydrogen gas into the reaction medium is usually accomplished by carrying out the reaction in a sealed vessel, containing the compound of formula (XI) or (XII), the solvent, the catalyst and the hydrogen. The pressure inside the reaction vessel can vary from about 1 to about 100 kg./cm.². The preferred pressure range, when the atmosphere inside the reaction vessel is substantially pure hydrogen, is from about 2 to about 5 kg./cm.². The hydrogenolysis is generally run at a temperature of from about 0° to about 60°C., and preferably from about 25° to about 50°C. Utilizing the preferred temperature and pressure values, hydrogenolysis generally takes place in a few hours, e.g., from about 2 hours to about 20 hours. The preferred noble metal catalysts used in this hydrogenolysis reaction are the type of agents known in the art for this kind of transformation, for example, nickel, palladium, platinum and rhodium. Palladium is particularly preferred. The catalyst is usually present in an amount from about 0.01 to about 25 weight-percent, and preferably from about 0.1 to about 10 weight-percent, based on the compound of formula (XI). It is often convenient to suspend the catalyst on an inert support; a particularly convenient catalyst is palladium suspended on an inert support such as carbon. When the hydrogenolysis is substantially complete, the desired product of formula (II, X₃ = H) is then isolated by standard methods, e.g., the catalyst is removed by filtration, the solvent evaporated and the product purified, if desired, by well known methods such as crystallization or by chromatography. When the starting compound of formula (XI) or (XII) is a benzyl ester (R¹ = R a = benzyl), the above catalytic hydrogenolysis procedure can also cause cleavage of the benzyl group, and the product is of formula (II) where X₃ and R¹ are each hydrogen. The 6-(substituted)hydroxymethylpenicillanic acid or ester of formula (XII) or (II, X₃ = H) where n is zero, can be oxidized by any of the methods known to convert sulfides to sulfoxides and sulfones, for example by means of 3-chloroperbenzoic acid as described above, to provide the corresponding sulfoxide or sulfone of formula (XII) OR (II, X₃ = H) and where in each n is 1 or 2, respectively. However, a preferred method for obtaining sulfones of formula (XI), (XII) or (II) is by employing the appropriate 6,6-dibromo-1,1-dioxopenicillanate ester (X) where n = 2 as starting material in the above described Method C. The starting aldehydes of formula R¹²R¹³CO wherein R¹² and R¹³ are as defined above are either available from a commercial source or are readily prepared from available starting materials by methods well known in the art, e.g. 1. Oxidation of the corresponding primary alcohols provided above as Wittig reagent precursors employing e.g. oxidants such as potassium dichromate, chromic acid/pyridine, catalytic oxidation in the presence of noble metals, manganese dioxide. 2. Reaction of the corresponding methyl substituted aromatic hydrocarbon with e.g. selenium dioxide. 3. Metal hydride reduction of the corresponding C₁-C₄alkoxycarbonyl compound at low temperature in the presence of ethereal solvents. Examples of suitable metal hydrides are lithium aluminum hydride and diisobutylaluminum hydride (DIBAL-H). 4. Reaction of an appropriate aromatic hydrocarbon precursor with n -butyl lithium and dimethylformamide. As indicated above, the compounds of the formulae (I) or (II) wherein R¹ is H, and salts thereof, in combinations with beta-lactam antibiotics, show synergistic activity in in vitro antibacterial tests. Such activity is demonstrated by measuring the minimum inhibitory concentrations (MIC's) in mcg/ml against a variety of microorganisms. The procedure which is followed is the one recommended by the International Collaborative Study on Antibiotic Sensitivity Testing (Ericcson and Sherris, Acta . Pathologica et Microbiologia Scandinav , Supp. 217, Section B: 64-68 [1971]), and employs brain heart infusion (BHI) agar and the inocula replicating device. Overnight growth tubes are diluted 100 fold for use as the standard inoculum (20,000-10,000 cells in approximately 0.002 ml are placed on the agar surface; 20 ml of BHI agar/dish). Twelve 2-fold dilutions of the test compound are employed, with initial concentration of the test drug being 200 mcg/ml. Single colonies are disregarded when reading plates after 18 hours at 37° C. The susceptibility (MIC) of the test organism is accepted as the lowest concentration of test compound or combination of compounds capable of producing complete inhibition of growth as judged by the naked eye. Those compounds of the formulae (I) and (II), where R¹ is H, and salts thereof, in combinations with known beta-lactam antibiotics are useful as industrial antimicrobials, for example in water treatment, slime control, paint preservation and wood preservation, as well as for topical application as disinfectants. In the case of use of these compounds for such an application, it is often convenient to admix the active ingredient with a non-toxic carrier, such as vegetable or mineral oil or an emollient cream. Similarly, they can be dissolved or dispersed in liquid diluents or solvents such as water, alkanols, glycols or mixtures thereof. In most instances it is appropriate to employ concentrations of the active ingredient of from about 0.1 percent to about 10 percent by weight, based on total composition. As also indicated above, the compounds of the formulae (I) and (II) wherein R¹ is R b are of more particular value as potent inhibitors of microbial beta-lactamases. By this mechanism they increase the antibacterial effectiveness of beta-lactam antibiotics (penicillins and cephalosporins) against many microorganisms, particularly those which produce a beta-lactamase. The ability of the said compounds of the formula (I) or (II) to increase the effectiveness of a beta-lactam antibiotic can be appreciated by reference to experiments in which the MIC values of the antibiotic alone, and a compound of the formula (I) or (II) having R¹ as hydrogen alone are determined. These MIC's are then compared with the MIC values obtained with a combination of the given antibiotic and the compound of the formula (I) or (II), wherein R¹ is hydrogen. When the antibacterial potency of the combination is significantly greater than would have been predicted from the potencies of the individual compounds, this is considered to constitute enhancement of activity. The MIC values of combinations are measured using the method described by Barry and Sabath in "Manual of Clinical Microbiology", edited by Lenette, Spaulding and Truant, 2nd Edition, 1974, American Society for Microbiology. The compounds of the formulae (I) and (II) wherein R¹ is hydrogen or the residue of an ester group readily hydrolyzable in vivo enhance the antibacterial effectiveness of beta-lactam antibiotics in vivo . That is, they lower the amount of the antibiotic which is needed to protect mice against an otherwise lethal inoculum of certain beta-lactamase producing bacteria. In determining such activity, acute experimental infections are produced in mice by the intraperitoneal inoculation of the mice with a standardized culture of the test organism suspended in 5 percent hog gastric mucin. Infection severity is standarized so that the mice receive a lethal dose of the organism (the lethal dose is the minimum inoculum of organism required to consistently kill 100 percent of the infected, non-treated control mice). The test compound in combination with the antibiotic is administered at various dosage levels, p . o . or i . p ., to groups of infected mice. At the end of the test, the activity of the mixture is assessed by counting the number of survivors among treated animals at a given dose. Activity is expressed as the percentage of animals which survive at a given dose, or calculated as a PD₅₀ (dose which protects 50% of the animals from infection). The ability of said compounds of formulae (I) and (II) to enhance the effectiveness of a beta-lactam antibiotic against beta-lactamase producing bacteria makes them valuable for co-administration with beta-lactam antibiotics in the treatment of bacterial infections in mammals, particularly man. In the treatment of a bacterial infection, the compound of the formula (I) or (II) can be co-mingled with the beta-lactam antibiotic, or in the case where R b is CH(R⁴)OCOR¹⁴ where R⁴ and R¹⁴ are as defined above, the beta-lactam antibiotic is chemically linked to the compound of formula (I) or (II), and the two agents thereby administered simultaneously. Alternatively, the compound of the formula (I) or (II) can be administered as a separate agent during a course of treatment with a beta-lactam antibiotic. In some instances it will be advantageous to pre-dose the subject with the compound of the formula (I) or (II) before initiating treatment with a beta-lactam antibiotic. When using a compound of formula (I) or (II) wherein R¹ is R b as defined above to enhance the effectiveness of a beta-lactam antibiotic, a mixture of said compound with the beta-lactam antibiotic, or the invention compound alone when R b is CH(R⁴)OCOR¹⁴, is administered preferably in formulation with standard pharmaceutical carriers or diluents. A pharmaceutical composition comprising a pharmaceutically acceptable carrier, a beta-lactam antibiotic and/or said compound of formula (I) or (II) will normally contain from about 5 to about 80 percent of the pharmaceutically acceptable carrier by weight. When using said compounds of formula (I) or (II) in combination with another beta-lactam antibiotic, said compounds can be administered orally or parenterally, i.e. intramuscularly, subcutaneously or intraperitoneally. Although the prescribing physician will ultimately decide the dosage to be used in a human subject, the ratio of the daily dosages of the compound of formula (I) or (II), wherein R¹ is R b , and the beta-lactam antibiotic will normally be in the range from about 1:3 to 3:1 by weight. Additionally, when using the compounds of formula (I) or (II) in combination with a beta-lactam antibiotic, the daily oral dosage of each component will normally be in the range from about 10 to about 200 mg per kilogram of body weight and the daily parenteral dosage of each component will normally be about 10 to about 40 mg per kilogram of body weight. These daily doses will usually be divided. In some instances, the prescribing physician will determine that dosages outside these limits are necessary. As will be appreciated by one skilled in the art, some beta-lactam compounds are effective when administered orally or parenterally, while others are effective only when administered by the parenteral route. When a compound of formula (I) or (II) is to be used simultaneously (i.e. co-mingled) with a beta-lactam antibiotic which is effective only on parenteral administration, a combination formulation suitable for parenteral use will be required. When a compound of formula (I) or (II) is to be used simultaneously (co-mingled) with a beta-lactam antibiotic which is effective orally or parenterally, combinations suitable for either oral or parenteral administration can be prepared. Additionally, it is possible to administer preparations of the active compounds of formula (I) or (II) orally, while at the same time administering a further beta-lactam antibiotic parenterally; and it is also possible to administer preparations of said compounds of formula (I) or (II) parenterally, while at the same time administering the further beta-lactam antibiotic orally. The present invention is illustrated by the following examples. However, it should be understood that the invention is not limited to the specific details of these examples. Proton and C¹³ nuclear magnetic resonance spectra were measured at 60, 90, 250 or 300 MHz for solutions in deuterochloroform (CDCl₃), deuterium oxide (D₂O), perdeutero acetone (CD₃COCD₃) or perdeutero dimethyl sulfoxide (DMSO-d₆) and peak positions are expressed in parts per million (ppm) downfield from tetramethylsilane. The following abbreviations are used: s, singlet; d, doublet; dd, doublet of doublets; t, triplet; q, quartet; m, multiplet; b, broad. EXAMPLE 1 6-alpha-Hydroxypenicillanate Esters A. Allyl ester A solution of 85 g 6-alpha-hydroxypenicillanic acid (0.39 mole) in 300 ml dimethylformamide was treated with 34 ml (0.39 mole) allyl bromide, 54 ml (0.39 mole) triethylamine and 2 g sodium bicarbonate and the mixture stirred at room temperature for 15 hours. After quenching the reaction with water and extraction with ethyl ether, the combined ether layers were washed with saturated sodium bicarbonate solution, water, dried (MgSO₄) and concentrated in vacuo to afford 43 g of crude product. The crude material was purified by silica gel column chromatography, eluting with 9:1 chloroform/ethyl acetate to yield 22.75 g (23%) of the allyl ester. ¹H-NMR(CDCl₃)ppm (delta): 1.42 (s, 3H), 1.60 (s, 3H), 4.45 (s; 1H), 4.5-5.0 (m, 3H), 5.2-6.2 (m, 4H). B. Pivaloyloxymethyl ester A mixture of 9 g (0.041 mole) 6-alpha-hydroxypenicillanic acid, 40 ml dimethylformamide, 7.4 ml (0.041 mole) diisopropylethylamine, 6 ml (0.041 mole) chloromethyl pivalate and 6.15 g (0.041 mole) sodium iodide was stirred at room temperature for 15 hours. Water was added, the mixture extracted with ethyl ether, the extracts dried and concentrated to give 9 g of crude ester which was purified on a silica gel golumn, eluting with chloroform/ethyl acetate (9:1). The combined product fractions amounted to 4.384 g (32%). C. Benzyl ester To a mixture of 20 g (0.092 mole) 6-alpha-hydroxypenicillanic acid, 12.9 ml, (0.092 mole) triethylamine, 1.105 g (0.013 mole) sodium bicarbonate and 200 ml dimethylformamide (DMF) was added 12.0 ml (0.101 mole) benzyl bromide. The mixture was stirred at room temperature for 20 hours, partitioned between ethyl ether and water and the aqueous phase adjusted to pH 2.0 with 6N hydrochloric acid. The layers were separated, the aqueous layer extracted twice again with ether, the combined ether layers washed with sodium bicarbonate solution, water, dried and the solvent evaporated. The residue was crystallized from hot chloroform/hexane to afford 9.1 g of colorless crystals, m.p. 165-167° C. D. (5-Methyl-2-oxo-1,3-dioxol-4-yl)methyl ester A mixture of 15 g (0.078 mole) (5-methyl-2-oxo-1,3-dioxol-4-yl)methyl bromide, 18.7 g (0.078 mole) sodium 6-alpha-hydroxypenicillanate in 225 ml DMF is stirred at room temperature for 4 hours, poured into ice and worked up as described above to provide the desired ester. EXAMPLE 2 6-Oxopenicillanate Esters A. Allyl 6-oxopenicillanate A mixture of 2.84 ml (0.04 mole) dimethylsulfoxide, 3.67 ml (0.026 mole) trifluoroacetic anhydride and 50 ml methylene chloride was stirred at -78° C. for ten minutes. A solution of 5.14 g (0.02 mole) allyl 6-alpha-hydroxypenicillanate in 10 ml methylene chloride was added at -78° C. and the resulting mixture stirred for 40 minutes. Triethylamine (7.24 ml, 0.052 mole) was added at this temperature and the mixture was gradually warmed to room temperature and quenched with water. After extracting with methylene chloride, the combined organic layers were washed with water (3x), dried and the solvent evaporated in vacuo to give the title compound as a yellow oil, 5.1 g (100%). ¹H-NMR(CDCl₃)ppm (delta): 1.60 (s, 6H), 4.75 (m, 2H), 4.82 (s, 1H), 5.1-6.3 (m, 3H), 5.82 (s, 1H). B. Pivaloyloxymethyl ester A mixture of 0.36 ml (5.06 mmole) dimethylsulfoxide, 0.47 ml (3.29 mmole) trifluoroacetic anhydride, 839 mg (2.53 mmole) pivaloyloxymethyl 6-alpha-hydroxypenicillanate and 5 ml methylene chloride was stirred at -78° C. for 30 minutes and 0.92 ml (6.58 mmole) of triethylamine was added. Work-up of the product as described in Part A, above, gave 788 mg (95%) of the desired ketone. ¹H-NMR(CDCl₃)ppm (delta): 1.3 (s, 9H), 1.65 (s, 6H), 4.85 (s, 1H), 5.8 (m, 3H). EXAMPLE 3 Allyl 6(E)-(2-pyridyl)methylenepenicillanate A mixture of 2.64 g (6.8 mmole) 2-picolyl triphenylphosphonium chloride and 0.265 g (6.8 mmole) sodium amide in 6 ml dry tetrahydrofuran (THF) was stirred at room temperature for 30 minutes. The resulting brown suspension was cooled to -78° C., a solution of 1.8 g (7.0 mole) allyl 6-oxopenicillanate in 4 ml dry THF was added in one portion and the mixture stirred at -78° C. for three minutes. The reaction was quenched by addition of saturated ammonium chloride solution, extracted with ethyl acetate and the combined organic layers were washed with water (3x), dried (MgSO₄) and concentrated in vacuo to give 3.3 g of red oil. The boil was purified by chromatography on a silica gel column to yield 1.35 g (60.7%) of the desired product as a yellow oil. ¹H-NMR(CDCl₃)ppm (delta): 1.50 (s, 3H), 1.58 (s, 3H), 4.57 (s, 1H), 4.65 (d, 2H), 5.15-6.15 (m, 3H), 6.17 (d, 1H, J=1Hz), 6.87 (d, 1H, J=1Hz), 7.2-7.4 (m, 2H), 7.60 (t of d, 1H), 8.62 (d of d); ¹³C-NMR(CDCl₃)ppm (delta): 26.04, 32.99, 62.77, 65.75, 70.01, 70.54, 119.10, 123.24, 124.02, 125.86, 131.06, 136.34, 144.66, 149.94, 152.13, 167.54, 168.73. EXAMPLE 5 Sodium 6(E)-(2-pyridyl)methylenepenicillanate A mixture of 0.120 g (0.38 mmole) allyl 6-(E)-(2-pyridyl)methylenepenicillanate, 20 mg tetrakis (triphenylphosphine)palladium (O) and 20 mg triphenylphosphine was dissolved in 3 ml ethyl acetate and to this, under a nitrogen atmosphere, was added 0.76 ml (0.38 mmole) 0.5 molar sodium 2-ethylhexanoate in ethyl acetate. The mixture is stirred at room temperature for two hours, the precipitate was collected by filtration, washed with ethyl acetate and dried in vacuo to obtain 57 mg (48%) of the title compound as a yellow solid. ¹H-NMR(D₂O)ppm (delta): 1.55 (s, 6H), 4.33 (s, 1H), 6.17 (d, 1H, J=0.5Hz), 7.03 (d, 1H, J=0.5Hz), 7.17-8.07 (m, 3H), 8.57 (m, 1H); infrared spectrum (KBr): 3433, 1756, 1605 cm⁻¹. EXAMPLE 6 Employing the appropriate starting material selected from the allyl esters provided in Example 4 in the procedure of Example 5 affords the following sodium salts in like manner. EXAMPLE 6A 6-Phenylthiomethylene penicillanic acid A mixture of 93 mg (0.26 mmole) allyl 6-phenylthiomethylenepenicillanate (mixed isomers) and 10 mg each of tetrakis (triphenylphosphine)palladium (O) and triphenylphosphene was dissolved in 1 ml ethyl acetate and 0.52 ml of 0.5M sodium 2-ethylhexanoate in ethyl acetate was added at room temperature and the resulting mixture was stirred for 10 hours under nitrogen. Since very little salt precipitated, the mixture was quenched with water and extracted with methylene chloride. The aqueous layer was acidified (pH 3.5) and extracted with methylene chloride. The dried extracts were concentrated in vacuo to afford 63 mg (75%) of the free acid as a mixture of isomers. ¹H-NMR(CDCl₃)ppm (delta): 1.5 (s, 2.1H), 1.53 (s, 0.9H), 1.6 (s, 2.1H), 1.65 (s, 0.9H), 4.4 (s, 0.7H), 4.5 (s, 0.3H), 5.38 (d, 0.7H). 5.7 (s, 0.3H), 6.7 (s, 0.3H), 7.1 (d, 0.7H), 7.5 (m, 5H). EXAMPLE 7 Allyl 1,1-Dioxo-6(E)-(2-pyridyl)methylenepenicillanate To a solution of 1.30 g (4.09 mmole) allyl 6(E)-(2-pyridyl)methylenepenicillanate in 15 ml methylene chloride was added 1.70 g (8.2 mmole) of 80-85% pure m-chloroperbenzoic acid and the mixture stirred under nitrogen for three hours at room temperature. After quenching with saturated sodium thiosulfate solution and water, the mixture was extracted with methylene chloride, the organic layer adjusted to pH 7.5 with saturated sodium bicarbonate solution, washed with water, dried (MgSO₄) and the solvent evaporated in vacuo to give 1.4 g (98%) of product as a yellow oil. The oil was purified by silica gel column chromatography, eluting with 7:3 hexane/ethyl acetate to yield 0.78 g (55%) of the title sulfone as colorless crystals. ¹H-NMR(CDCl₃)ppm (delta): 1.48 (s, 3H), 1.63 (s, 3H), 4.45 (s, 1H), 4.73 (d, 2H), 5.1-6.2 (m, 3H), 5.77 (d, 1H, J=0.5Hz), 7.27 (d, 1H, J=0.5Hz), 7.1-8.1 (m, 3H), 8.6 (m, 1H); ¹³C-NMR(CDCl₃)ppm (delta): 18.53, 20.43, 63.18, 64.25, 66.63, 72.04, 119.91, 124.64, 126.03, 130.68, 132.83, 136.77, 150.31, 166.86, 168.11. Infrared (KBr) cm⁻¹: 1323, 1586, 1759, 1783, 3437. EXAMPLE 8 Allyl 1,1-dioxo-6(E)-(2-hydroxyethylidene) penicillanate To a solution of 0.190 g (0.61 mmole) allyl 1,1-dioxo-6(E)-formylmethylenepenicillanate in 4 ml of dry tetrahydrofuran at -78° C. was added 0.61 ml (0.61 mmole) of 1M diisobutylaluminum hydride in hexane. The mixture was stirred at -78° C. for ten minutes, quenched with methanol, stirred at room temperature for 20 minutes and filtered. The filtrate was concentrated in vacuo to give 0.258 g of crude product which was diluted with water, extracted with chloroform and the organic layer dried (MgSO₄). Evaporation of chloroform afforded 160 mg of material which was further purified by silica gel column chromatography, eluting with 4:1 chloroform/ethyl acetate to yield 113 mg (60%) of the title compound. ¹H-NMR(CDCl₃)ppm (delta): 1.40 (s, 3H), 1.60 (s, 3H), 2.60 (bs, 1H), 4.3 (m, 2H), 4.4 (s, 1H), 4.7 (d, 2H), 5.1-6.0 (m, 3H), 5.25 (d, 1H), 6.38 (m, 1H). EXAMPLE 9A Allyl 6(E)-[(1-oxoquinolin-2-yl)methylene]-1,1-dioxopenicillanate Allyl 6(E)-[(quinolin-2-yl)methylene]-1-oxopenicillanate (obtained as byproduct from preparation of corresponding sulfone, see previous Example, asterisk) (124 mg, 0.313 mmole) was dissolved in 5 ml methylene chloride and 195 mg (0.904 mmole) off 80% m-chloroperbenzoic acid was added. The mixture was stirred at room temperature for 48 hours, quenched with water and extracted with methylene chloride. The extracts were washed with saturated sodium bicarbonate solution, water, dried and concentrated in vacuo to a yellow oil. The oil was purified by silica gel column chromatography to give 45 mg (35%) of the title N-oxide as a yellow solid. ¹H-NMR(CDCl₃)ppm (delta): 1.45 (s, 3H), 1.6 (s, 3H), 4.45 (s, 1H), 4.7 (m, 2H), 5.0-6.0 (m, 3H), 5.85 (d, 1H), 7.3-8.0 (m, 7H). EXAMPLE 10 Sodium 1,1-Dioxo-6(E)-(2-pyridyl)methylenepenicillanate A mixture of allyl 1,1-dioxo-6(E)-(2-pyridyl)methylenepenicillanate (0.14 g, 0.4 mmole), 20 mg tetrakis (triphenylphosphine)palladium (O) and 20 mg triphenylphosphine was dissolved in 2 ml ethyl acetate and under nigrogen was added 0.8 ml (0.4 mmole) of a 0.5M solution of sodium 2-ethyl hexanoate in ethyl acetate. The resulting mixture was stirred at room temperature for five minutes. The resulting precipitate was filtered, washed with ethyl acetate and dried to afford 0.13 g (95%) of the sodium salt as a yellow solid. ¹H-NMR(D₂O)ppm (delta): 1.50 (s, 3H), 1.60 (s, 3H), 4.23 (s, 1H), 5.90 (d, 1H, J=1Hz), 7.1-8.0 (m, 4H), 8.57 (m, 1H). Infrared spectrum (KBr) cm⁻¹: 1590, 1621, 1770, 3454. EXAMPLE 11 Allyl 1,1-Dioxo-6(E)-(1-oxo-2-pyridyl)methylenepenicillanate A solution of allyl 1,1-dioxo-6(E)-(2-pyridyl)methylenepenicillanate (100 mg, 0.286 mmole) in 5 ml of methylene chloride was treated with m-chloroperbenzoic acid (120 mg, 0.59 mmole) and stirred at room temperature for three days. The mixture was quenched with saturated sodium thiosulfate solution and extracted with methylene chloride. The organic layer was neutralized with saturated sodium bicarbonate solution, washed with water, dried and concentrated to give 82 mg of yellow oil. The yellow oil was purified by silica gel column chromatography using ethyl acetate as eluent to give 22 mg (21%) of title compound and 14 mg (13%) of a byproduct, 2,3-epoxypropanyl 1,1-dioxo-6(E)-(1-oxo-2-pyridyl)methylenepenicillanate. Allyl 1,1-dioxo-6(E)-(1-oxo-2-pyridyl)methylenepenicillanate: ¹H-NMR(CDCl₃)ppm (delta): 1.5 (s, 3H), 1.6 (s, 3H), 4.45 (d, 1H), 4.7 (d, 2H), 5.1-6.0 (m, 3H), 5.8 (s, 1H), 7.1-8.4 (m, 5H). EXAMPLE 13 Pivaloyloxymethyl 6(E)-(methylthio)methylenepenicillanate A mixture of 2.4 mmole (methylthiomethyl)triphenylphosphonium chloride, 2.4 mmole sodium amide in 5 ml dry tetrahydrofuran (THF) was stirred at room temperature for 20 minutes. To the resulting yellow solution at -78° C. was added a solution of 788 mg (2.4 mmole) pivaloyloxymethyl 6-oxopenicillanate in 10 ml of dry THF. The mixture was stirred at -78° C. for one minute, poured into saturated ammonium chloride solution and extracted with ethyl acetate. The organic layer was dried (Na₂SO₄) and the solvent evaporated in vacuo to afford 774 mg of crude product which was purified by silica gel column chromatography, eluting with chloroform to yield 220 mg (24.5%) of pure product. ¹H-NMR(CDCl₃)ppm (delta): 1.25 (s, 9H), 1.50 (s, 3H), 1.65 (s, 3H), 2.45 (s, 3H), 4.45 (s, 1H), 6.85 (m, 3H), 7.0 (d, 1H). EXAMPLE 14 Pivaloyloxymethyl 6-(E)methylsulfonylmethylene penicillanate 1-oxide (A) and the corresponding 1,1-dioxide (B) To a solution of 215 mg (0.58 mmole) pivaloyloxymethyl 6(E)-(methylthiomethyl)methylenepenicillanate in 5 ml methylene chloride was added 375 mg (1.74 mmole, 3 equivalents) 80% m-chloroperbenzoic acid. The mixture was stirred at room temperature four hours, quenched with water, saturated sodium thiosulfate solution, sodium bicarbonate and extracted with chloroform. The organic phase was washed three times with water, dried (MgSO₄) and concentrated in vacuo to give 200 mg of the mixed products. The crude mixture was purified by silica gel chromatography, eluting with chloroform/ethyl acetate (9:1) to yield 25 mg of the 1-oxide (A) and 45 mg of the 1,1-dioxide product (B). (A): ¹H-NMR(CDCl₃)ppm (delta): 1.21 (s, 9H), 1.3 (s, 3H), 1.7 (s, 3H), 3.1 (s, 3H), 4.7 (s, 1H), 5.8 (AB quartet, 2H), 5.85 (d, 1H), 7.1 (d, 1H); infrared spectrum (CHCl₃) cm⁻¹: 1333, 1759, 1807, 2927, 2960. (B): ¹H-NMR(CDCl₃)ppm (delta): 1.2 (s, 9H), 1.45 (s, 3H), 1.6 (s, 3H), 3.15 (s, 3H), 4.5 (s, 1H), 5.6 (d, 1H), 5.8 (AB quartet, 2H), 7.2 (d, 1H); infrared spectrum (CHCl₃) cm⁻¹: 1324, 1758, 1800, 2929, 2956. EXAMPLE 15 Allyl 6-alpha-(N-methylpyrrol-2-yl)hydroxymethyl-1,1-dioxopenicillanate Allyl 6-alpha-bromo-1,1-dioxopenicillanate (520 mg, 1.48 mmole) was dissolved in 10 ml dry tetrahydrofuran (THF) and cooled to -78° C. A solution of methylmagnesium bromide (0.52 ml, 2.85M in THF) was added and the mixture stirred for five minutes at -78° C. N-methylpyrrole-2-carboxaldehyde (162 mg, 0.16 ml) was added and stirring continued at -78° C. for 20 minutes. The mixture was poured into saturated ammonium chloride solution, extracted with ethyl acetate and the organic layer dried (MgSO₄). Evaporation of solvent in vacuo gave 466 mg of crude product which was purified by silica gel chromatography, eluting with chloroform/ethyl acetate (9:1) to give 180 mg (32%) of the pure title compound. ¹H-NMR(CDCl₃)ppm (delta): 1.4 (s, 3H), 1.62 (s, 3H), 3.68 (s, 3H), 4.0-4.4 (m, 1H), 4.42 (s, 1H), 4.5-4.8 (m, 3H), 5.0-6.0 (m, 4H), 6.0-6.7 (m, 3H). EXAMPLE 16 Allyl 6(E)-(N-methylpyrrol-2-yl)methylene-1,1-dioxopenicillanate Allyl 6-alpha-(N-methylpyrrol-2-yl)hydroxymethyl-1,1-dioxopenicillanate (180 mg, 0.47 mmole) was dissolved in 3 ml tetrahydrofuran and 0.15 ml acetic anhydride and 0.2 ml pyridine were added. The mixture was stirred at room temperature for one hour. The reaction was quenched with water and extracted with ethyl acetate. The organic layer was dried and solvent evaporated in vacuo to yield 162 mg of material still containing starting material. This was dissolved in methylene chloride (3 ml) and 0.15 ml acetyl chloride and 0.2 ml pyridine added. The mixture was stirred two hours at room temperature and worked up as before to give 140 mg of crude product which was purified by silica gel column chromatography to give 72 mg (42%) of pure product. Recrystallization from ethyl acetate gave colorless needles. ¹H-NMR(CDCl₃)ppm (delta): 1.45 (s, 3H), 1.65 (s, 3H), 3.7 (s, 3H), 4.4 (s, 3H), 4.6-4.9 (m, 2H), 5.1-6.4 (m, 4H), 6.6-7.0 (m, 2H), 7.5 (dd, 1H). EXAMPLE 17 Sodium 6(E)-(N-methylpyrrol-2-yl)methylene-1,1-dioxopenicillanate A solution of 46 mg allyl 6(E)-(N-methylpyrrol-2-yl)methylene-1,1-dioxopenicillanate, 5 mg tetrakis (triphenylphosphine)palladium (O), 4 mg triphenylphosphine and one ml methylene chloride was stirred under nitrogen for five minutes. The resulting mixture was diluted with one ml ethyl acetate and 0.25 ml sodium 2-ethyl hexanoate in ethyl acetate added. After stirring at room temperature for one hour, the mixture was filtered and the precipitate washed with ethyl acetate and ethyl ether to give 30 mg of yellow solid. ¹H-NMR(D₂O)ppm (delta): 1.50 (s, 3H), 1.60 (s, 3H), 3.65 (s, 3H), 4.10 (s, 1H), 5.4 (s, 1H), 6.1-6.5 (m, 1H), 7.0 (s, broad, 2H), 7.2-7.4 (m, 1H); infrared (KBr) cm⁻¹: 1568, 1616, 1660, 1745, 3465. EXAMPLE 18 Employing the appropriate aldehyde of formula R¹³CHO in the procedure of Example 15 affords the corresponding compounds of the formula below EXAMPLE 19 Allyl 6-(furan-2-yl)methylene-1,1-dioxopenicillanate, (E)- and (Z)-isomers To a solution of 310 mg (0.84 mmole) allyl 6-alpha-(furan-2-yl)hydroxymethyl-1,1-dioxopenicillanate in 5 ml methylene chloride was added 0.14 ml (1 mmole) triethylamine and 0.1 ml (0.924 mmole) trifluoromethylsulfonyl chloride and the mixture stirred under nitrogen at room temperature for two hours. The reaction was quenched with water, extracted with methylene chloride, the extracts dried (MgSO₄) and solvent evaporated in vacuo to give 330 mg of crude product. Purification by silica gel column chromatography eluting with chloroform afforded 130 mg of product which was estimated to be a 4:1 mixture of (E)- and (Z)-isomers by HPLC. ¹H-NMR(CDCl₃)ppm (delta): 1.47 (s, 3H), 1.61 (s, 3H), 4.47 (s, 1H), 4.75 (d, 2H), 5.1-6.2 (m, 4H), 5.52 (dd, 1H), 6.8 (m, 1H), 7.15 (d, 1H), 7.6 (d, 1H). EXAMPLE 20 Allyl 6(E)-(N-acetylpyrrol-2-yl)methylene-1,1-dioxopenicillanate A. Allyl 6-(N-acetylpyrrol-2-yl)acetoxymethyl-1,1-dioxopenicillanate Allyl 6-(N-acetylpyrroyl-2-yl)hydroxymethyl-1,1-dioxopenicillanate (210 mg, 0.51 mmole) was dissolved in 3 ml tetrahydrofuran and 0.16 ml acetic anhydride and 0.2 ml pyridine were added and the mixture stirred at room temperature for 24 hours. The reaction was quenched with water, extracted with methylene chloride, the extracts dried and concentrated to give 171 mg (75%) of yellow crystals, ¹H-NMR(CDCl₃)ppm (delta): 1.4 (s, 3H), 1.6 (s, 3H), 2.15 (s, 3H), 2.55 (s, 3H), 4.15-4.3 (dd, 1H), 4.4 (s, 1H), 4.6-4.8 (m, 3H), 5.1-6.0 (m, 3H), 6.1-6.6 (m, 2H), 6.6-7.4 (m, 2H). B. The N,O-diacetate product from Part A, 170 mg (0.38 mmole) was dissolved in methylene chloride and 47 mg (0.38 mmole) 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) was added. The mixture was stirred at room temperature for one hour. Water was added and the mixture extracted with methylene chloride. The extracts were dried and concentrated to yield 158 mg of oil which was purified by silica gel chromatography using 2% ethyl acetate in chloroform as eluant to give 108 mg of product as a pale yellow oil. ¹H-NMR(CDCl₃)ppm (delta): 1.5 (s, 3H), 1.6 (s, 3H), 2.55 (s, 3H), 4.4 (s, 1H), 4.65 (d, 2H), 5.0-6.0 (m, 4H), 6.3 (t, 1H), 6.8 (dd, 1H), 7.2 (m, 1H), 3.2 (d, 1H). EXAMPLE 21 Allyl 6(E)-phenylmethylene-1,1-dioxopenicillanate and Corresponding (Z)-isomer A. Employing 1.98 mmoles allyl 6-phenylhydroxymethyl-1,1-dioxopenicillanate, 4.2 mmoles acetyl chloride and 0.4 ml pyridine in the method of Part A of the preceding Example gave 0.7 g (84%) of allyl 6-phenylacetoxymethyl-1,1-dioxopenicillanate as a light yellow gum. ¹H-NMR(CDCl₃)ppm (delta): 1.3 and 1.4 (s, 3H), 1.62 (s, 3H), 2.08 and 2.2 (s, 3H), 4.2 (dd, 1H), 4.4 (s, 1H), 4.5 (d, 1H), 4.65 (d, 2H), 6.25 (m, 1H), 7.3 (m, 5H). B. To a solution of the product of Part A (0.7 g, 1.66 mmole) in methylene chloride was added 0.25 ml (1.67 mmole) 1,5-diazabicyclo[5.4.0]undec-5-ene (DBU) and the mixture stirred at room temperature for ten minutes. Water and methylene chloride were added, the layers separated and the organic extracts washed with 0.1N hydrochloric acid, brine and water. The extracts were dried (Na₂SO₄) and solvent evaporated to give 660 mg of crude product which was purified by column chromatography on 100 g silica gel, eluting with chloroform to provide 68 mg (11%) of the (Z)-isomer ¹H-NMR(CDCl₃)ppm (delta): 1.45 (s, 3H) 1.60 (s, 3H), 4.45 (s, 1H), 4.68 (d, 2H), 5.37 (d, 1H), 5.1-6.05 (m, 3H), 7.35 (d, 1H), 7.45 (s, 1H). Subsequent eluate fractions gave 100 mg (16.7%) of the (E)-isomer of the title compound as a colorless oil which formed crystals upon standing. ¹H-NMR(CDCl₃)ppm (delta): 1.45 (s, 3H), 1.53 (s, 3H), 4.45 (s, 1H), 4.75 (d, 2H), 5.45 (d, 1H), 5.2-6.2 (m, 3H), 7.36 (d, 1H), 7.45 (s, 5H). EXAMPLE 22 The following compounds were prepared from the appropriate hydroxy compound selected from those provided in Example 18 by the procedure of Example 19. EXAMPLE 24 6(E)-Phenylmethylenepenicillanic acid-1,1-dioxide To a solution of 0.1 g (0.28 mmole) allyl 6(E)-phenylmethylene-1,1-dioxopencillanate, 20 mg triphenylphosphine and 20 mg tetrakis (triphenylphosphine)palladium (O) in 3 ml ethyl acetate was added 0.57 ml of 0.5M sodium 2-ethylhexanoate and the mixture was stirred at room temperature for one hour. After standing for 65 hours in the refrigerator no precipitate had formed. The mixture was diluted with ethyl acetate and water, the separated aqueous layer was adjusted to pH 1.8 with dilute hydrochloric acid, extracted with fresh ethyl acetate, the extracts dried (Na₂SO₄) and solvent evaporated in vacuo to give 62 mg (69%) of product as yellow crystals (from acetone). ¹H-NMR(CD₃COCD₃)ppm (delta): 1.55 (s, 3H), 1.65 (s, 3H), 4.43 (s, 1H), 5.93 (d, 1H), 7.3-7.9 (m, 6H), 8.7 (bs, 1H); infrared spectrum (KBr) cm⁻¹: 1327, 1685, 1737, 1772, 2929, 2961, 3108, 3477. EXAMPLE 25 Potassium 6(E)-(1-Methylimidazol-2-yl)methylene-1,1-dioxopenicillanate A. Allyl 6-(1-Methylimidazol-2-yl)acetoxymethyl-1,1-dioxopenicillanate 6-(1-Methylimidazol-2-yl)hydroxymethyl-1,1-dioxopenicillanate (472 mg, 1.23 mmole) was acetylated by the method of Example 20, Part A, to provide 392 mg (75%) of the acetoxy compound as a mixture of two isomers. ¹H-NMR(CDCl₃)ppm (delta): 1.4 (s, 1.5H), 1.5 (s, 1.5), 1.6 (s, 1.5H), 1.7 (s, 1H), 2.2 (s, 3H), 3.7 (s, 1.5H), 3.75 (s, 1.5H), 4.0-6.0 (m, 8H), 6.3-6.5 (m, 1H), 6.8 (m, 1H), 7.0 (m, 1H). B. Allyl 6(E)-(1-Methylimidazol-2-yl)methylene-1,1-dioxopenicillanate The product obtained in Part A, above, (392 mg, 0.920 mmole), 5 ml methylene chloride and 0.115 ml 1,5-diazabicyclo[4,3.0]non-5-ene (DBN) was converted to the title ester by the method of Example 20, Part 3, in 53% yield. ¹H-NMR(CDCl₃)ppm (delta): 1.5 (s, 3H), 1.6 (s, 3H), 3.7 (s, 3H), 4.35 (s, 1H), 4.7 (m, 2H), 5.0-6.1 (m, 3H), 5.7 (d, 1H), 6.9 (m, 1H), 7.1 (d, 1H), 7.2 (m, 1H). C. The allyl ester obtained in Part B (163 mg, 0.45 mmole) was converted to the title potassium salt by the method of Example 17, but employing potassium 2-ethylhexanoate in place of the corresponding sodium salt. The product obtained amounted to 143 mg (87% yield) of the single (E) isomer. ¹H-NMR(DMSO)ppm (delta): 1.38 (s, 3H), 1.45 (s, 3H), 3.8 (s, 4H), 5.68 (s, 1H), 7.15 (s, 1H), 7.35 (m, 2H); ¹³C-NMR(DMSO)ppm (delta): 18.5, 20.2, 32.5, 64.4, 66.2, 70.35, 115.2, 124.6, 129.9, 130.6, 141.2, 167.9, 169.0. Infrared spectrum (KBr) cm⁻¹: 1614, 1762, 3428. EXAMPLE 26 The procedure of Example 10 was repeated with 50 mg (0.12 mmole) allyl 6-(3-allyloxy-2-pyridyl)methylene-1,1-dioxopenicillanate by employing 5.2 mg triphenylphosphine, 5.2 mg tetrakis (triphenylphosphine)palladium (O) and 0.24 mmoles of potassium 2-ethylhexanoate (2 molar equivalents of starting allyl ester) in 1.5 ml ethyl acetate and stirring the resulting mixture for 18 hours. The ethyl acetate was drawn off with a pipette and the residue washed twice with 1 ml portions of ethyl acetate to give a dark solid, 43 mg, which was found to be the dipotassium salt of 6-(E)-(3-hydroxy-2-pyridyl)methylene-1,1-dioxopenicillanic acid. ¹H-NMR(D₂O)ppm (delta): 1.56 (s, 3H), 1.62 (s, 3H), 4.27 (s, 1H), 6.00 (d, 1H), 7.29 (m, 2H), 7.80 (d, 1H), 8.04 (d, 1H). EXAMPLE 27 Allyl 6(E)-(2-pyrimidinyl)methylenepenicillanate A. 2-Hydroxymethylpyrimidine A slurry of sodium ethoxide, prepared, from 7.44 g (323 mmole) sodium metal and 300 ml absolute ethanol, was cooled to room temperature, 18 g (163 mmole) hydroxyacetamidine hydrochloride and 8.06 ml (81 mmole) 3-dimethylaminoacrolein were added and the mixture heated to reflux. Dimethylamine was distilled off slowly while periodically adding ethanol to maintain the solvent volume. After refluxing for nine hours, the mixture was then stirred at room temperature for 18 hours. The solvent was evaporated under reduced pressure and the residue placed on a silica gel column and eluted with 19:1 ethyl acetate/methanol to afford 4.1 g of product (46% yield). B. 2-Pyrimidinylmethyltriphenylphosphonium chloride 2-Hydroxymethylpyrimidine, 4.096 g (37.2 mmole) was dissolved in 80 ml methylene chloride and 8.6 ml (37.2 mmole) thionyl chloride was added dropwise (exothermic). The mixture was stirred for 15 minutes, neutralized with saturated sodium bicarbonate solution and extracted with methylene chloride. The extracts were dried and solvent evaporated to give 3.67 g of 2-chloromethylpyrimidine. ¹H-NMR(CDCl₃)ppm (delta): 4.82 (s, 2H), 7.3 (t, 1H), 8.9 (d, 2H). A mixture of 3.565 g (27.7 mmole) of 2-chloromethylpyrimidine in 30 ml toluene and 7.269 g (27.7 mmole) triphenylphosphine were heated at reflux for 18 hours. The resulting precipitate was collected by filtration and dried to yield 9.06 g (65% for two steps). C. A mixture of 2.187 g (5.6 mmole) of the Wittig reagent from Part B, above, 218.4 mg (5.32 mmole) sodium amide and 30 ml dry tetrahydrofuran (THF) was stirred at room temperature for 1.5 hours. A solution of 1.44 g (5.65 mmole) allyl 6-oxopenicillanate in 10 ml dry THF was added in one portion at -78° C., the resulting mixture stirred for five minutes, poured into saturated ammonium chloride solution and extracted with chloroform. The organic phase was washed with saturated ammonium chloride, brine, dried (MgSO₄) and the solvent evaporated in vacuo . The resulting oil was purified by column chromatography on silica gel, eluting with 9:1 chloroform/ethyl acetate to provide 560 mg of the pure product. ¹H-NMR(CDCl₃)ppm (delta): 1.5 (s, 3H), 1.6 (s, 3H), 4.6 (s, 1H), 4.7 (m, 2H), 5.1-6.3 (m, 3H), 6.2 (d, 1H), 7.0 (d, 1H), 7.0-7.35 (m, 1H), 8.8 (d, 2H). EXAMPLE 28 Allyl Ester of 1,1-Dioxo-6(E)-(2-pyrimidinyl-methylenepenicillanic Acid and Potassium Salt A. Allyl 6(E)-(2-pyrimidinyl)-methylenepenicillanate (560 mg, 1.69 mmole) and 3-chloroperbenzoic acid 730 mg (3.38 mmole) were dissolved in 10 ml methylene chloride and stirred under a nitrogen atmosphere four hours. The resulting mixture was quenched with water, extracted with methylene chloride, the extracts were washed with sodium thiosulfate, neutralized with sodium bicarbonate, washed with brine, dried and concentrated in vacuo to give 460 mg of crude oil. The oil was purified by silica gel column chromatography, eluting with 9:1 chloroform/ethyl acetate to afford 180 mg of the desired allyl ester as a pale yellow solid. ¹H-NMR(CDCl₃)ppm (delta): 1.45 (s, 3H), 1.65 (s, 3H), 4.5 (s, 1H), 4.75 (m, 2H), 5.2-6.3 (m, 3H), 5.75 (s, 1H), 7.1-7.5 (m, 2H), 8.9 (d, 2H). B. Reaction of the above allyl ester with triphenyl phosphine, tetrakis (triphenylphosphine)palladium (O) and potassium 2-ethyl hexanoate by the method of Example 10 gave the desired potassium salt in 89% yield as a pale pink solid. ¹H-NMR(D₂O)ppm (delta): 1.6 (s, 3H), 1.68 (s, 3H), 4.4 (s, 1H), 6.1 (s, 1H), 7.48 (s, 1H), 7.54 (t, 1H), 8.88 (d, 2H); ¹³C-NMR(D₂O)ppm (delta): 20.9, 22.7, 68.8, 68.9, 74.6, 124.5, 132.5, 139.9, 160.9, 163.2, 172.5, 175.5. Infrared spectrum (KBr) cm⁻¹: 1560, 1615, 1771, 3439. EXAMPLE 29 A. To 1.0 g 6-alpha-hydroxypenicillanic acid in 25 ml methylenechloride is added 50 mg diisopropylcarbodiimide and 0.5 ml 2,2,2-trichloroethanol. The mixture is stirred overnight, the solvent removed by evaporation in vacuo and the crude product purified by column chromatography on silica gel to afford 2,2,2-trichloroethyl 6-alpha-hydroxypenicillanate. B. To 1.0 g 6-alpha-hydroxypenicillanic acid in 50 ml dioxane is added 0.5 g p-toluene sulfonic acid and 0.4 g dihydropyran and the mixture warmed to 50° C., then stirred overnight at room temperature. Evaporation of solvent and purification by silica gel column chromatography affords 2-tetrahydropyranyl 6-alpha-hydroxypenicillanate. EXAMPLE 30 Benzyl 6-oxopenicillanate To a solution of 1.8 ml (0.025 mole) dimethylsulfoxide in 2 ml methylene chloride at -60° C. was added dropwise a solution of 2.12 ml (0.015 mole) trifluoroacetic anhydride in 5 ml methylene chloride. The mixture was stirred at -60° C. for 20 minutes, a solution of 350 mg (1.14 mmole) benzyl 6-alpha-hydroxypenicillanate in 5 ml methylene chloride added and stirring continued at -60° C. for 60 minutes. Triethylamine (0.50 ml) was added, the cooling bath removed, the mixture warmed to 0° C., poured into ice-water and extracted with methylene chloride. The organic layer was dried, concentrated in vacuo to a small volume which was diluted with benzene and washed three times with ice-water. The benzene layer was dried, solvent evaporated in vacuo to yield 230 mg (67%) of product as yellow crystals. The proton-NMR spectrum in CDCl₃ showed the product to be very pure. EXAMPLE 31 Benzyl 6-(2-Pyridyl)hydroxymethylpenicillanate A. Benzyl 6-bromo-6(2-pyridyl)hydroxymethylpenicillanate A solution of 9.0 g (0.02 mole) benzyl 6,6-dibromopenicillanate in 200 ml freshly distilled toluene is cooled to -78° C. and 9 ml of 2.2M t-butyllithium in pentane was added dropwise. The resulting mixture was stirred for 30 minutes, 2.14 g (0.02 mole) 2-pyridinecarboxaldehyde was added and stirring continued for another 40 minutes. The reaction was quenched by dropwise addition of acetic acid in toluene. After stirring for one hour the cooling bath was removed, the mixture warmed to -10° C., diluted with 200 ml toluene, washed with water (5 times) and dried (Na₂SO₄). The toluene solution was charged to a column of Florisil (1 Kg.) and eluted with 2:1 toluene/ethyl acetate. The product fractions were combined and evaporated in vacuo to a brown syrup, 4.2 g, which was used in the next step. B. The brown syrup from Part A (4.2 g) was dissolved in 50 ml benzene and 2.65 g tributyltin hydride was added. The mixture was heated at reflux for 2 hours, additional tributyltin hydride (1.65 g) was added and heating at reflux continued overnight. The solvent was evaporated in vacuo , the residue washed with hexane and charged to a column containing 500 g silica gel, and eluted with 2:1 toluene/ethyl acetate to obtain 425 mg of the title compound. ¹H-NMR(CDCl₃)ppm (delta): 1.35 (s, 3H), 1.7 (s, 3H), 4.0 (dd, 1H), 4.5 (s, 1H), 5.1 (s, 2H), 5.2 (d, 1H), 5.4 (d, 1H), 7.0-7.8 (m, 3H), 8.5 (m, 1H). EXAMPLE 32 6-(2-Pyridyl)hydroxymethylpenicillanic acid 1,1-dioxide A. Benzyl 6-(2-pyridyl)hydroxymethyl-1,1-dioxopenicillanate To a solution of 0.40 g benzyl 6-(2-pyridyl)hydroxymethylpenicillanate in 5 ml methylene chloride was added 0.20 g m -chloroperbenzoic acid and the mixture stirred at room temperature for one hour. Thin-layer chromatography indicated the mixture to contain some sulfoxide. An additional 0.2 g m -chloroperbenzoic acid was added and the mixture stirred overnight. The mixture was diluted with methylene chloride, washed in turn with saturated sodium thiosulfate solution, water, saturated sodium bicarbonate solution and the organic layer was concentrated in vacuo . The residue was taken up in ethyl acetate, washed with sodium bicarbonate solution, water, brine, and dried (Na₂SO₄). Evaporation of solvent gave 330 mg of the desired benzyl ester as a brown oil which was purified by silica gel column chromatography, eluting with 11:9 ethyl acetate/hexane to afford 60 mg of yellow oil. ¹H-NMR(CDCl₃)ppm (delta): 1.25 (s, 3H), 1.52 (s, 3H), 4.1 (dd, 1H), 4.5 (s, 1H), 4.72 (d, 1H), 5.5 (d, 2H), 5.8 (d, 1H), 7.1-8.0 (m, 3H), 8.5 (m, 1H). B. A suspension of 118 mg 10% Pd/C catalyst in 10 ml tetrahydrofuran (THF) and 4 ml water was prehydrogenated for 20 minutes at 3 atmospheres hydrogen pressure. To this was added 130 mg of the benzyl ester obtained in Part A, above, in 4 ml of the same THF/water mixture. This was hydrogenated at 50 psi (3.5 km/cm²) for 30 minutes. An additional 129 mg of 10% Pd/C was added and hydrogenation continued at 50 psi for two hours. The catalyst was removed by filtration, the solvent evaporated in vacuo and the residue partitioned between water and ethyl acetate. The aqueous layer was freeze dried to give 85 mg of the desired acid. ¹H-NMR(D₂O)ppm (delta): 1.3 (s, 3H), 1.5 (s, 3H), 4.4 (s, 1H), 5.0-5.35 (m, 2H), 5.9 (d, 1H); infrared spectrum (KBr) cm⁻¹: 1620, 1731, 3407. C. When the above procedure is carried out, but employing only a total of 175 mg of m -chloroperbenzoic acid (an equimolar amount) in Part A, the product isolated is a mixture of corresponding alpha- and beta-sulfoxides. EXAMPLE 33 The following materials are blended to obtain a powder of uniform composition in the proportions by weight indicated below: Blend (1375 mg) is filled into suitably sized hard gelatin capsules to obtain capsules of 250 mg potency of each active ingredient. Higher or lower potency capsules are prepared by appropriate adjustment of capsule size and fill weight. The relative weights of active ingredients are adjusted to obtain capsules wherein the weight ratio of active ingredients is other than one, e.g., the ingredients are blended in a weight ratio of 0.75, 1.5, 0.5 and 3.0, respectively, with a 1700 mg fill weight/capsule to obtain capsules having 225 mg potency of (a) and 450 mg potency of (b). In like manner, the other beta-lactamase inhibitors of the present invention are formulated with other conventional beta-lactam antibiotics for oral use. Alternatively, ingredients (a) and (b) in the above formulation are replaced by 2 parts by weight of 6-[D-(2-amino-2-phenylacetamido)]penicillanoyloxymethyl 6-(2-pyridyl)methylene-1,1-dioxopenicillanate hydrochloride. EXAMPLE 34 Injectable Preparation Equal parts by weight of cefoperazone sodium and potassium 1,1-dioxo-6(E)-(2-pyrazinyl)methylenepenicillanate are combined with 20 parts by weight of water. Using methods standard in the pharmaceutical art, the solution is sterile filtered, filled into vials, the vials loosely rubber stoppered, and the vials freeze dried on trays. The fill volume is such that each freeze dried vial, now sealed under vacuum, will contain 500 mg of each active ingredient. Prior to injection, each vial is made up by injection of 10 ml of sterile water for injection, through the rubber plug, and shaken to dissolve. The solution to be injected 1-10 ml is removed through the rubber plug via hypodermic needle. EXAMPLE 35 Allyl 6-(2-thiazolyl)acetoxymethyl-1,1-dioxopenicillanate Acetylation of 0.5 g (1.29 mmole) allyl 6-(2-thiazolyl)hydroxymethyl-1,1-dioxopenicillanate (provided in Example 18) with 0.396 g (3.88 mmole) acetic anhydride and 0.307 g (3.88 mmole) pyridine in 5 ml tetrahydrofuran was carried out by the method of Example 20, Part A, stirring at room temperature four hours. The mixture was then diluted with methylene chloride, washed with water until neutral (pH 6.0-6.5), the organic phase dried (Na₂SO₄) and the solvent evaporated to afford 0.688 g of the desired acetate. ¹H-NMR(CDCl₃)ppm(delta): 1.52 (s, 3H), 1.70 (s, 3H), 2.35 (s, 3H), 4.4-4.6 (m, 2H), 4.6-5.0 (m, 3H), 5.2-6.4 (m, 3H), 6.65 (d, 1H), 7.4 (d, 1H), 7.8 (d, 1H). EXAMPLE 36 Allyl 6-(2-thiazolyl)methylene-1,1-dioxopenicillanate and its Hydrolysis to Potassium Salt A. The above acetoxy ester (0.688 g, 1.29 mmole) was mixed with 0.16 g (1.29 mmole) 1,5-diazabicyclo[4.3.0]-non-5-ene (DBN) and 5 ml methylene chloride and stirred for one hour at room temperature. The resulting mixture was diluted with methylene chloride, washed with water (2 x 50 ml), dried (Na₂SO₄) and the solvent evaporated to give an oil. This was chromatographed on a silica gel column, eluting with 1:1 ethyl acetate/hexane to yield 0.189 g (39%) of light yellow oil. ¹H-NMR(CDCl₃)ppm(delta): 1.53 (s, 3H), 1.65 (s, 3H), 4.33 (s, 1H), 4.55 (d, 2H), 5.0-5.4 (m, 2H), 5.45 (s, 1H), 5.4-6.0 (m, 1H), 7.1 (m, 1H), 7.75 (m, 1H), 7.65 (d, 1H). B. Hydrolysis of the allyl ester obtained above by the method of Example 25, Part C afforded potassium 6-(2-thiazolyl)methylene-1,1-dioxopenicillanate in 84.7% step yield as a yellow solid. ¹H-NMR 250MHz (DMSO-D₆)ppm(delta): 1.40 (s, 3H), 1.45 (s, 3H), 3.80 (s, 1H), 5.83 (s, 1H), 7.66 (s, 1H), 8.04 (m, 2H). EXAMPLE 37 Tetrabutylammonium 6-[D-(2-[1-methyl-2-methoxycarbonylvinylamino]-2-phenylacetamido)]penicillanate To 300 ml chloroform was added 39.3 g 6-[D-(2-amino-2-phenylacetamido)]penicillanic acid trihydrate, 50 ml of water was added and the pH of the mixture adjusted to 8.5 by addition of 40% aqueous tetrabutylammonium hydroxide. The layers were separated, the aqueous layer was saturated with sodium sulfate and extracted with fresh chloroform. The extracts and initial lower layer were combined and the solvent was evaporated to about 250 ml total volume. To this was added 150 ml methyl acetoacetate and 30 g of anhydrous magnesium sulfate. The mixture was heated at reflux for three hours, the mixture allowed to settle and the warm organic layer decanted. The clear chloroform solution was allowed to cool to obtain crystals of the title compound in 52% yield, m.p. 182-184° C. (decomp.). ¹H-NMR(CDCl₃)ppm(delta): 0.8-2.0 (m, 4H), 1.88 (s, 3H), 3.1-3.6 (m, 8H), 3.6 (s, 3H), 4.17 (s, 1H), 4.58 (s, 1H), 5.05 (d, 1H), 5.38-5.6 (m, 2H), 6.78 (d, 1H), 7.35 (s, 5H), 9.4 (d, 1H). EXAMPLE 38 Tetrabutylammonium 6-[D-(2-[1-methyl-2-methoxycarbonylvinylamino]-2-[4-hydroxyphenyl]acetamido)]penicillanate To 300 ml of dichloromethane is added 41.9 g of 6-(2-amino-2-[4-hydroxyphenyl]acetamido)penicillanic acid trihydrate and 50 ml of water, and then the pH is adjusted to 8.5 using 40% aqueous tetrabutylammonium hydroxide. Three layers are obtained. The upper layer is removed, saturated with sodium sulfate and then it is extracted with dichloromethane. The extracts are combined with the middle layer and the lower layer, and the resulting mixture is evaporated in vacuo to give an oil which crystallized on trituration with acetone. This affords 44.6 g of tetrabutylammonium 6-(2-amino-2-[4-hydroxyphenyl]acetamido)penicillanate. The above salt is added to 150 ml of methyl acetoacetate and the suspension is heated at ca . 65° C. until a clear solution is obtained (8 minutes). The mixture is allowed to cool, and then the solid is recovered by filtration. The solid is washed with methyl acetoacetate, followed by diethyl ether, to give 49.25 g of tetrabutylammonium 6-(2-[1-methyl-2-methoxycarbonylvinylamino]-2-[4-hydroxyphenyl]acetamido)penicillanate crystals. EXAMPLE 39 A. Potassium (6-alpha, 8S)-6-pyrimidin-2-yl)hydroxymethyl-1,1-dioxopenicillanate To a solution of 300 mg (0.79 mmole) of the first eluted isomer of allyl 6-alpha-(pyrimidin-2-yl)hydroxymethyl-1,1-dioxopenicillanate (obtained in Example 18) in 4 ml ethyl acetate was added 30 mg tetrakis (triphenylphosphine)palladium (O) and 30 mg triphenylphosphine. The mixture was stirred under nitrogen to solvate the reagents (5-10 minutes) and 1.57 ml (0.79 mmole) potassium 2-ethylhexanoate in ethyl acetate was added. After stirring at room temperature for 20 minutes, the mixture was filtered and the cake washed with ethyl acetate and dried to afford 53 mg of yellow solid. The filtrate was treated with ethyl ether to precipitate a second crop, 152 mg; total yield 69%. ¹H-NMR, 250 MHz, (DMSO-d₆)ppm (delta): 1.33 (s, 3H), 1.44 (s, 3H), 3.77 (s, 1H), 3.95 (d or d, J=2, J=6, 1H), 4.89 (d, J=2, 1H), 5.1 (d, J=6, 1H), 6.33 (s, 1H), 7.48 (t, J=4, 1H), 8.84 (d, J=4, 2H). B. Potassium (6-alpha, 8R)-6-(pyrimidin-2-yl)hydroxymethyl-1,1-dioxopenicillanate A solution of 300 mg (0.79 mmole) of the second eluted isomer of allyl 6-alpha-(pyrimidin-2-yl)hydroxymethyl-1,1-dioxopenicillanate (obtained in Example 18) was converted to its potassium salt by the above procedure to afford 236 mg (79%). ¹H-NMR, 250 MHz, (DMSO-d₆)ppm (delta): 1.30 (s, 3H), 1.42 (s, 3H), 3.65 (s, 1H), 4.60 (dd, J=2, J=8, 1H), 4.75 (d, J=2, 1H), 5.15 (d, J=8, 1H), 7.47 (t, J=4, 1H), 8.85 (d, J=4, 2H). EXAMPLE 40 A. Allyl (6-alpha, 8S)-6-(pyrimidin-2-yl)acetoxymethyl-1,1-dioxopenicillanate To a solution of 785 mg (2.1 mmole) of the first eluted isomer of allyl 6-alpha-(pyrimidin-2-yl)hydroxymethyl-1,1-dioxopenicillanate (obtained in Example 18) in 4 ml methylene chloride was added 0.45 ml (5.6 mmole) pyridine and 0.53 ml (5.6 mmole) acetic anhydride and the mixture was stirred at room temperature for 2.5 hours. The mixture was diluted with 30 ml methylene chloride, extracted with water (7 x 60 ml), dried over anhydrous magnesium sulfate and filtered. Evaporation in vacuo gave 813 mg (92%) of the title compound. ¹H-NMR(CDCl₃)ppm (delta): 1.4 (s, 3H), 1.6 (s, 3H), 2.2 (s, 3H), 4.45 (s, 3H), 4.45 (dd, 1H), 4.75 (m, 2H), 4.95 (d, 1H), 5.2-5.6 (m, 2H), 5.7-6.3 (m, 1H), 6.45 (d, 1H), 7.35 (t, 1H), 8.85 (d, 1H). B. Allyl (6-alpha, 8R)-6-pyrimidin-2-yl)acetoxymethyl-1,1-dioxopenicillanate Acetylation of the second, eluted isomer of allyl 6-alpha-(pyrimidin-2-yl)hydroxymethyl-1,1-dioxopenicillanate (obtained in Example 18) by the above method gave an 88% yield of the title compound. ¹H-NMR(CDCl₃) ppm (delta): 1.4 (s, 3H), 1.6 (s, 3H), 4.45 (s, 1H), 4.50 (dd, J=1, J=8, 1H), 4.75 (m, 2H), 4.8 (d, J=1, 1H), 5.25-5.6 (m, 2H), 5.7-6.3 (m, 1H), 6.4 (d, J=8, 1H), 7.35 (t, J=6, 1H), 8.8 (d, J=6, 1H). EXAMPLE 41 A. Potassium (6-alpha, 8S)-6-(pyrimidin-2-yl)acetoxymethyl-1,1-dioxopenicillanate A solution of 789 mg (1.86 mmole) allyl (6-alpha, 8S)-6-(pyrimidin-2-yl)acetoxymethyl-1,1-dioxopenicillanate in 4 ml ethyl acetate was reacted by the procedure of Example 39 to give 342 mg (43%) of the desired potassium salt which was purified by preparative MPLC eluting with 9:1 water/acetonitrile to give 105 mg of product (85% pure by HPLC analysis). B. Potassium (6-alpha, 8R)-6-(pyrimidin-2-yl)acetoxymethyl-1,1-dioxopenicillanate A solution of 666 mg (1.57 mmole) allyl (6-alpha, 8R)-6-(pyrimidin-2-yl)acetoxymethyl-1,1-dioxopenicillanate was reacted by the same procedure to give 339 mg (51%) of crude product which was purified by preparative MPLC with 9:1 water/acetonitrile to yield 162 mg of pure isomer. ¹H-NMR, 250 MHz, (DMSO-d₆)ppm (delta): 1.34 (s, 3H), 1.44 (s, 3H), 2.17 (s, 3H), 3.65 (s, 1H), 4.15 (dd, J=2, J=8, 1H), 4.97 (d, J=2, 1H), 6.27 (d, J=8, 1H), 7.50 (t, J=5, 1H), 8.85 (d, J=5, 2H). EXAMPLE 42 Employing the appropriate starting 6-R¹³CHOH-substituted-1,1-dioxopenicillanate ester provided in Example 18, the following acetate esters are prepared by the method of Examples 20 or 40. EXAMPLE 43 The 8-acetoxy-3-carbonyloxyallyl esters provided in Example 25A and 42 are converted to the potassium salt of the formula below by the method of Example 39 EXAMPLE 45 Potassium 6-(Imidazol-2-yl)hydroxymethyl-1,1-dioxopenicillanate A mixture of 141 mg (0.38 mmole) allyl 6-(imidazol-2-yl)hydroxmethyl-1,1-dioxopenicillanate [mixed isomers obtained in Example 18], 12 mg tetrakis (triphenylphosphine)palladium (O), 12 mg triphenylphosphine, 0.76 ml (0.38 mmole) potassium 2-ethylhexanoate and 2 ml ethyl acetate was stirred under nitrogen for one hour. The precipitated product was recovered by filtration to give 143 mg (100%) of yellow solid which was found to contain two isomers by high pressure liquid chromatography analysis. Infrared (KBr): 3382, 1780, 1728 and 1615 cm⁻¹. EXAMPLE 46 A. Benzyl 6-(2-thiazolyl)hydroxymethyl-1,1-dioxopenicillanate A solution of 17.79 g (44 mmole) benzyl 6-alpha-bromo-1,1-dioxopenicillanate in 250 ml dry tetrahydrofuran was reacted with an equimolar amount of methylmagnesium bromide at -78° C., then after stirring for one minute, an equimolar amount of thiazol-2-carboxaldehyde added and stirring continued for 10 minutes. An equimolar amount of acetic acid was then added, and after stirring five minutes, the mixture was poured into 500 ml water. Extraction with ethyl acetate, washing of the extracts with water, drying (MgSO₄), and evaporation of solvent in vacuo gave 16.93 g (89%) of crude product which showed two spots on TLC. The crude product was purified by silica gel column chromatography, eluting with chloroform/ethyl acetate, 96:4, to afford 4.72 g of a more polar isomer, 2.98 g of a less polar isomer and 0.5 g of mixed isomers; (total yield 43%). More polar isomer: ¹H-NMR(CDCl₃)ppm (delta): 1.25 (s, 3H), 1.55 (s, 3H), 4.3 (dd, 1H), 4.45 (s, 1H), 4.65 (bs, 1H), 4.9 (d, 1H), 5.2 (m, 2H), 5.55 (d, 1H), 7.35 (m, 6H), 7.75 (d, 1H). Less polar isomer: ¹H-NMR(CDCl₃)ppm (delta): 1.2 (s, 3H), 1.5 (s, 3H), 4.35 (m, 2H), 4.75 (d, 1H), 5.1 (m, 2H), 5.55 (d, 1H), 7.2 (m, 6H), 7.6 (d, 1H). B. Diphenylmethyl 6-(2-thiazolyl)hydroxymethyl-1,1-dioxopenicillanate Repeating the above procedure with diphenylmethyl 6-alpha-bromo-1,1-dioxopenicillanate on a 20 millimolar scale and purification by silica gel chromatography eluting with 9:1 chloroform/ethyl acetate gave 2.464 g of a less polar (LP) isomer and 3.029 g of a more polar (MP) isomer. More polar isomer: ¹H-NMR(CDCl₃)ppm (delta): 1.06 (s, 3H), 1.52 (s, 3H), 4.1-4.3 (m, 1H), 4.42 (s, 1H), 4.76 (d, 1H), 5.45 (d, 1H), 6.82 (s, 1H), 7.05-7.3 (m, 11H), 7.56 (d, 1H). Less polar isomer: ¹H-NMR(CDCl₃)ppm (delta): 1.2 (s, 3H), 1.65 (s, 3H), 4.35 (dd, 1H), 4.55 (s, 1H), 4.83 (d, 1H), 5.65 (dd, 1H), 6.95 (s, 1H), 7.2-7.4 (m, 11H), 7.75 (d, 1H). EXAMPLE 48 A. (6-alpha, 8R)-6-(Thiazol-2-yl)propionyloxymethyl-1,1-dioxopenicillanic Acid A mixture of 1.89 g of 10% palladium-on-carbon catalyst in 20 ml of a 9:7 (v/v) mixture of tetrahydrofuran (THF) and water was saturated with hydrogen and a solution of 689 mg (1.4 mmole) benzyl (6-alpha, 8R)-6-(thiazol-2-yl)propionyloxymethyl-1,1-dioxopenicillanate in 13 ml THF and 7 ml water was added. The resulting mixture was hydrogenated at 3 bars pressure for 20 minutes, the catalyst was then removed by filtration, the filtrate extracted with ethyl acetate (3 x 200 ml) and the extracts dried (MgSO₄). Evaporation of solvent in vacuo gave 330 mg yellow solid. B. (6-alpha, 8R)-6-(Thiazol-2-yl)benzoyloxymethyl-1,1-dioxopenicillanic Acid The title compound was obtained by the above procedure from the corresponding benzyl ester in 57% yield. ¹H-NMR(D₂O)pm (delta): 1.38 (s, 3H), 1.55 (s, 3H), 4.25 (s, 1H), 4.44 (dd, 1H), 5.05, (d, 1H), 6.68 (d, 1H), 7.4 (t, 7H), 7.55 (t, 1H), 7.58 (d, 1H), 7.7 (d, 1H), 7.95 (d, 1H). Infrared (KBr): 3473, 1782, 1729, 1622 cm⁻¹. EXAMPLE 49 A. (6-alpha, 8S)-6-(Thiazol-2-yl)ethoxycarbonyloxymethyl-1,1-dioxopenicillanic Acid To a solution of 557 mg (0.954 mmole) diphenylmethyl (6-alpha, 8S)-6-(thiazol-2-yl)ethoxycarbonyloxymethyl-1,1-dioxopenicillanate in 5 ml methylene chloride was added 0.62 ml (5.72 mmole) anisole. The mixture was cooled to -5° and a mixture of 382 mg (2.86 mmole) anhydrous aluminum chloride and 2 ml nitromethane was added slowly over 15 minutes. The reaction mixture was diluted with 50 ml ethyl acetate, water added and the pH adjusted to pH 7.5. The aqueous layer was separated, acidified to pH 3 and extracted with ethyl acetate. Evaporation of solvent gave a residual glass which was dissolved in ethyl ether, filtered and hexane added to the filtrate to effect precipitation. After filtering to recover solid and drying, 211 mg (53%) of product was obtained. ¹H-NMR, 300 MHz, (CDCl₃)ppm (delta): 1.40 (t, 3H), 1.53 (s, 3H), 1.67 (s, 3H), 4.28-4.42 (m, 3H), 4.50 (s, 1H), 4.92 (s, 1H), 6.58 (d, 1H), 7.53 (d, 1H), 7.93 (d, 1H). Infrared (KBr): 3443, 1797, 1754 cm⁻¹. B. Employing the (6-alpha, 8R)-isomer of the starting diphenylmethyl ester provided in Example 47 in the above procedure affords the corresponding (6-alpha, 8R)-isomer of 6-(thiazol-2-yl)ethoxycarbonyloxymethyl-1,1-dioxopenicillanic acid. ¹H-NMR, 300 MHz, (CDCl₃)ppm (delta): 1.34 (t, 3H), 1.53 (s, 3H), 1.65 (s, 3H), 4.2-4.4 (m, 3H), 4.44 (s, 1H), 5.04 (s, 1H), 6.67 (d, 1H), 7.53 (d, 1H), 7.90 (d, 1H). Infrared (KBr): 3418, 1803, 1750 cm⁻¹. EXAMPLE 51 A. Allyl 6-bromo-6-(2-thiazolyl)hydroxymethyl-1,1-dioxopenicillanate A solution of 8.84 g (20 mmole) allyl 6,6-dibromo-1,1-dioxopenicillanate in 100 ml dry tetrahydrofuran was cooled to -78° C., 7.02 ml (20 mmole) methylmagnesium bromide was added and the mixture stirred for 5 minutes. A solution of 2.26 g (20 mmole) thiazole-2-carboxaldehyde in 10 ml of the same solvent was added at -78° C. and the resulting mixture stirred for 20 minutes. Acetic acid (1.2 ml) was added, the mixture was poured into water and extracted with ethyl acetate and chloroform. The combined organic layers were dried (Na₂SO₄) and the solvent evaporated in vacuo to yield 8.5 g crude product as a glass. The crude glass was purified by column chromatography on silica gel, eluting with 89:11 chloroform/ethyl acetate to afford 6.2 g (72%) of pure product which was found to be a single isomer. ¹H-NMR (CDCl₃)ppm (delta): 1.4 (s, 3H), 1.6 (s, 3H), 4.0 (bs, 1H), 4.42 (s, 1H), 4.6 (d, 2H), 5.3 (s, 1H), 5.55 (s, 1H), 5.1-6.3 (m, 3H), 7.35 (d, 1H), 7.75 (d, 1H). B. Benzyl 6-bromo-6-(2-thiazolyl)hydroxymethyl-1,1-dioxopenicillanate Employing benzyl 6,6-dibromo-1,1-dioxopenicillanate in place of the allyl ester in the above procedure provided the title compound as an orange foam in quantitative yield. ¹H-NMR(CDCl₃)ppm (delta): 1.32 (s, 3H), 1.60 (s, 3H), 4.5 (s, 2H), 5.2-5.8 (m, 4H), 7.3 (d, 1H), 7.4 (s, 5H), 7.9 (d, 1H). C. The following compounds were prepared in like manner by the procedure of Part A. EXAMPLE 52 A. Acylation of the compounds provided in the previous Example by the method of Example 42 or 47 provided the following compounds in like manner. A. Where R a is allyl and R¹⁸ is CH₃CO: B. Where R a is benzyl and R¹⁸ is CH₃CO: C. Alternatively the compounds of the above formula are prepared upon carrying out the method of Example 51 with acylation of the reaction mixture prior to isolation of product by the following general method: To a solution of 1.0 equivalent of 6,6-dibromopenicillanate ester in tetrahydrofuran at -78° C. was added 1.3 equivalents of methylmagnesium bromide dissolved in the same solvent and the mixture stirred for 5-10 minutes. The appropriate aldehyde (R¹³CHO), 1.3 equivalents in the same solvent was added at -78° C. to -68° C. and the reaction mixture stirred for 30 to 60 minutes. Then, 1.3 equivalents of acetyl chloride was added, stirring at -78° C. continued for 10 minutes and the product then isolated by pouring into ice/water, extracting with ethyl acetate, drying and evaporation of solvent in vacuo . Where R¹⁸ is CH₃CO: EXAMPLE 53 A. Benzyl 6-beta-(thiazol-2-yl)acetoxymethyl-1,1-dioxopenicillanate To a solution of 74.6 g (134 mmole) benzyl 6-bromo-6-(thiazol-2-yl)acetoxymethyl-1,1-dioxopenicillanate in 850 ml benzene was added 43.99 g (151.2 mmole) tri-n-butyltin hydride. The mixture was heated at reflux for 5.5 hours and allowed to stand overnight. The solvent was evaporated in vacuo , the residue taken up in hexane and extracted with acetonitrile (2 x 250 ml). The acetonitrile layer was evaporated, the residue slurried in ethyl ether, filtered and the cake washed with ether to give 33.28 g of colorless crystals. Another 2.8 g was obtained by evaporation of the filtrate to dryness. The residue was taken up in benzene and 10 g tri-n-butyltin hydride was added. The mixture was refluxed for one hour and worked up as for the first crop; combined yield 56.3%. The first crop, above, was purified by column chromatography on silica gel, eluting with 9:1 chloroform/ethyl acetate. The product fractions were concentrated, slurried with 4:1 ethyl ether/ethyl acetate, filtered, washed with ether to afford 22.6 g white solid. ¹H-NMR(CDCl₃)ppm (delta): 1.25 (s, 3H), 1.53 (s, 3H), 2.1 (s, 3H), 4.58 (s, 1H), 4.80 (d, 1H), 5.2 (dd, 1H), 5.22 (q, 2H), 6.75 (d, 1H), 7.35 (s, 5H), 7.4 (d, 1H), 7.8 (d, 1H). ¹³C-NMR(CDCl₃)ppm (delta): 17.7, 19.9, 20.5, 54.5, 63.06, 63.6, 63.8, 64.5, 68.1, 121.8, 128.8, 128.9, 134.3, 142.6, 164.6, 166.5, 169.2, 170.5. B. The following compounds were obtained in a similar manner by debromination of the remaining compounds provided in Example 52. B. 6-beta-(Thiazol-2-yl)acetoxymethyl-1,1-dioxopenicillanic acid obtained in Part A, above, was converted to the corresponding potassium salt by treatment of an aqueous slurry of the acid with an equimolar amount of potassium bicarbonate in water and purification by medium pressure liquid chromatography on a C₁₈ column , eluting with 9:1 water/acetonitrile to obtain the corresponding potassium salt in 60% yield. ¹H-NMR (DMSO-d₆)ppm (delta): 1.37 (s, 3H), 1.48 (s, 3H), 2.07 (s, 3H), 3.80 (s, 1H), 4.92 (dd, 1H), 5.12 (d, 1H), 6.55 (d, 1H), 7.89 (m, 2H). Infrared (KBr): 3454, 1788, 1630 cm⁻¹. EXAMPLE 55 A. 6-(Benzothiazol-2-yl)methylene-1,1-dioxopenicillanic acid, mixture of E and Z isomers To a solution of 400 mg (0.91 mmole) 6-(benzothiazol-2-yl)acetoxymethyl-1,1-dioxopenicillanic acid in 5 ml water was added a solution of 0.15 g (1.82 mmole) sodium bicarbonate in 2 ml water and the resulting mixture was stirred for two hours. The reaction mixture (pH 7.55) was freeze dried. The lyophilate was taken up in 8 ml water, adjusted to pH 3.5 with dilute hydrochloric acid, extracted with ethyl acetate, the organic layers dried (MgSO₄) and the solvent evaporated in vacuo . The resulting product was shown to be a 60:40 mixture of (E) and (Z) isomers by its NMR spectrum. ¹H-NMR(CDCl₃) ppm (delta): 1.55 (s, 1.2H), 1.6 (s, 1.8H), 1.65 (s, 1.2H), 1.67 (s, 1.8H), 4.55 (s, 0.6H), 4.58 (s, 0.4H), 5.38 (s, 0.4H), 5.74 (s, 0.6H), 7.44 (s, 0.4H), 7.48 (s, 0.6H), 7.5 (m, 4H), 7.89 (d, 1H), 8.07 (d, 0.4H), 8.15 (d, 0.6H). B. Similar treatment of the appropriate 6-R¹³-CH(OAc)-substituted-1,1-dioxopenicillanic acid, provided above, afforded the compound of the formula below as a mixture of (E) and (Z) isomers. EXAMPLE 56 A. Potassium 6-bromo-6-(thiazol-2-yl)acetoxymethyl-1,1-dioxopenicillanate Reaction of 96 mg (0.2 mmole) allyl 6-bromo-6-(thiazol-2-yl)acetoxymethyl-1,1-dioxopenicillanate (provided in Example 52) by the method of Example 45 for 10 minutes and worked up as described to provide 46 mg (48%) of yellow solid product. ¹H-NMR(D₂O)ppm (delta): 1.45 (s, 3H), 1.6 (s, 3H), 4.4 (s, 1H), 5.55 (s, 1H), 6.85 (s, 1H), 7.72 (d, 1H), 7.86 (d, 1H). B. Potassium 6-bromo-6-(thiazol-2-yl)hydroxymethyl-1,1-dioxopenicillanate Similarly, reaction of 220 mg allyl 6-bromo-6-(thiazol-2-yl)hydroxymethyl-1,1-dioxopenicillanate (provided in Example 51) by the above method for 20 minutes gave a 52% yield of the title salt as a pale yellow solid. ¹H-NMR(DMSO-d₆)ppm (delta): 1.35 (s, 3H), 1.47 (s, 3H), 3.75 (s, 0.4H), 3.83 (s, 0.6H), 5.3 (d, 0.4H), 5.32 (d, 0.6H), 5.45 (s, 0.6H), 5.5 (s, 0.4H), 7.6-8.0 (m, 2H). Infrared (KBr): 3442, 1794, 1633 cm⁻¹. EXAMPLE 57 Potassium (6-beta, 8S)-6-(thiazol-2-yl)hydroxymethylpenicillanate A. Allyl 6-bromo-6-(thiazol-2-yl)hydroxymethylpenicillanate To a solution of 9.971 g (24.99 mmole) allyl 6,6-dibromopenicillanate in 150 ml dry tetrahydrofuran cooled to -78° C. under nitrogen, was added 8.77 ml of 2.85M (24.99 mmole) methylmagnesium bromide in THF and the mixture stirred for 15 minutes. A solution of 2.824 g (24.99 mmole) thiazol-2-carboxaldehyde in 5 ml THF was added and the mixture was stirred again for 20 minutes at -78° C. The reaction was quenched by addition of 1.43 ml (24.99 mmole) glacial acetic acid, the mixture stirred for 10 minutes, then allowed to warm to room temperature. It was then poured into water, extracted with 2 x 250 ml ethyl acetate, the extracts washed with water (2 x 250 ml), dried (MgSO₄) and the solvent evaporated in vacuo to give 10.36 g orange oil. The oil was purified by column chromatography on silica gel eluting with 9:1 chloroform/ethyl acetate to yield 4.54 g yellow solid (mixture of isomers) and 0.443 g yellow foam, more polar isomer only, (total yield 46%). For the yellow foam: ¹H-NMR(CDCl₃)ppm(delta): 1.56 (s, 3H), 1.76 (s, 3H), 4.60 (s, 1H), 4.7 (m, 2H), 4.9-6.4 (m, 6H), 7.45 (m, 1H), 7.8 (m, 1H). B. Allyl 6-beta-(thiazol-2-yl)hydroxymethylpenicillanate The more polar isomer from Part A, 200 mg (0.462 mmole) was dissolved in 1 ml benzene and 0.183 ml (0.693 mmole, 1.5 equivalents) tri- n -butyltin hydride in benzene was added. The mixture was heated at reflux for three hours and allowed to stand overnight at room temperature. The solvent was evaporated in vacuo , the residue taken up in acetonitrile, washed with hexane and evaporated to a small volume which was placed on a silica gel column and eluted with chloroform to yield 73 mg (45%) of the desired product. ¹H-NMR(CDCl₃)ppm (delta): 1.65 (s, 3H), 1.87 (s, 3H), 3.8-4.4 (m, 1H), 4.05-4.3 (dd, 1H), 4.65 (s, 1H), 4.78 (m, 2H), 5.3-5.6 (m, 2H), 5.6-6.3 (m, 3H), 7.45 (m, 1H), 7.85 (m, 1H). C. The product obtained in Part B, 73 mg (0.206 mmole), was converted to potassium salt by the method of Example 45 to provide 58 mg (80%) of the title compound as a yellow solid. ¹H-NMR, 300 MHz, (D₂O)ppm (delta): 1.36 (s, 3H), 1.55 (s, 3H), 4.13 (dd, 1H), 4.18 (s, 1H), 5.32 (d, 1H), 5.41 (d, 1H), 7.56 (d, 1H), 7.60 (d, 1H). EXAMPLE 58 A. By employing the appropriate aldehyde, R¹³CHO in place of thiazol-2-carboxaldehyde in the procedure of Example 57, Part A, afforded the corresponding compounds of the formula below in like manner. B. Debromination of the above compounds by the method of Example 57, Part B, gave the following compounds. C. Reaction of the allyl esters provided above by the method of Example 45 provided the following potassium salts PREPARATION A 6-Chloropyridin-2-ylmethyltriphenylphosphonium Chloride (i) 6-Chloro-2-methylpyridine-1-oxide To a solution of 5.1 g (40 mmole) 6-chloro-2-picoline in 50 ml methylene chloride was added 8.625 g (40 mmole) of 80% m-chloroperbenzoic acid and the mixture was stirred at room temperature for 15 hours. The reaction was quenched with 0.5 ml saturated sodium thiosulfate and adjusted to pH 7.5 with sodium bicarbonate solution. The organic layer was washed with water, dried (Na₂SO₄) and solvent evaporated to give 4.84 g of N-oxide. ¹H-NMR(CDCl₃)ppm (delta): 2.6 (s, 3H), 7.0-8.0 (m, 3H). (ii) 6-Chloro-2-acetoxymethylpyridine A solution of 4.8 g (0.035 mole) of the above N-oxide in 15 ml acetic anhydride was heated at 100° C. for one hour and distilled in vacuo to give 2.39 g of the desired product, b.p. 125-128°/0.7mm, as a colorless oil. ¹H-NMR(CDCl₃)ppm (delta): 2.1 (s, 3H), 5.1 (s, 2H), 7.0-7.8 (m, 3H). (iii) 6-Chloro-2-pyridylmethanol Hydrolysis of the product obtained in Part (ii) in 10 ml 2N hydrochloric acid at 70° C. for one hour, followed by neutralization (K₂CO₃), extraction with chloroform and evaporation of solvent from the dried extract gave 1.87 g of crude alcohol which was purified by column chromatography on silica gel to yield 0.982 g pure material. ¹H-NMR(CDCl₃)ppm (delta): 4.8 (s, 2H), 5.3 (bs, 1H), 7.0-7.8 (m, 3H). (iv) 6-Chloro-2-chloromethylpyridine 6-Chloro-2-pyridylmethanol, 0.982 g (6.84 mmole) in 10 ml methylene chloride was treated with 0.814 g thionyl chloride at room temperature for one hour. The mixture was neutralized with saturated sodium bicarbonate solution, extracted with methylene chloride, the extracts dried and solvent evaporated to give 815 mg of product as colorless crystals. ¹H-NMR(CDCl₃)ppm (delta): 4.7 (s, 2H), 7.1-8.0 (m, 3H). (v) The Wittig reagent was prepared by dissolving 815 mg (5 mmole) of the product obtained in Part (iv) and 1.318 g (5 mmole) triphenylphosphine in toluene (10 ml) and heating the mixture at reflux for six hours. The precipitated product was collected by filtration to give 1.368 g (65%) of the title compount. ¹H-NMR(DMSO)ppm (delta): 5.5 (s, 1H), 5.8 (s, 1H), 7.2-8.2 (m, 18H). (vi) 4-Methoxypyridin-2-ylmethyltriphenylphosphonium chloride Starting with 2-methyl-4-methoxypyridine-1-oxide (2.1 g) in the procedure of Part (ii) afforded 2.5 g of 2-acetoxymethyl-4-methoxypyridine which was contaminated with about 25% of 5-acetoxy-2-methyl-4-methoxypyridine. This mixture was dissolved in methanol (10 ml) containing 1.118 g (20.7 mmole) sodium methoxide and stirred at reflux for one hour. The methanol was evaporated in vacuo , the residue diluted with water, neutralized with dilute hydrochloric acid and extracted with chloroform. The organic layers was washed with brine, dried (MgSO₄) and concentrated in vacuo to give 853 mg (41%) 2-hydroxymethyl-4-methoxypyridine. ¹H-NMR(CDCl₃)ppm (delta): 3.9 (s, 3H), 4.72 (s, 2H), 5.35 (bs, 1H), 6.7 (dd, 1H), 6.95 (d, 1H), 8.3 (d, 1H). The hydroxymethyl compound obtained above was converted to 2-chloromethyl-4-methoxypyridine by the method of Part (iv), above, to provide 0.895 g (5.68 mmole). This was reacted with an equimolar amount of triphenylphosphine in toluene (10 ml) at reflux for 20 hours. The precipitated product was filtered to give 860 mg of the title compound as a yellow solid. PREPARATION B 2-Quinolinylmethyltriphenylphosphonium Chloride A solution of 2-chloromethylquinoline, 6.25 g (0.035 mole), and 9.20 g (0.035 mole) triphenylphosphine in 80 ml toluene was heated at reflux for three hours. The precipitated solid was collected on a filter and dried in vacuo to give 3.5 g (23%) of product as a brown solid. PREPARATION C 3-Allyloxy-2-pyridylmethyltriphenylphosphonium Chloride (i) 3-Allyloxy-2-hydroxymethylpyridine To a sodium methoxide, methanol mixture made from 1.43 g (62 mmole) sodium metal and 100 ml methanol was added 5.9 g (31 mmole) 3-hydroxy-2-hydroxymethylpyridine and the methanol removed in vacuo . The resulting residue was dissolved in 80 ml dimethylsulfoxide (DMSO) and 3.0 ml (34.7 mmole) allyl bromide in 20 ml DMSO was added over 20 minutes at room temperature. The mixture was stirred for two hours, the DMSO distilled in vacuo and the residue partitioned between chloroform/water. The aqueous phase was adjusted to pH 7.5 and extracted three times with chloroform. The combined organic layers were washed with water, brine, dried (Na₂SO₄) and concentrated to give 3.48 g (68%) of the desired ether. (ii) 3-Allyloxy-2-chloromethylpyridine The product from Part (i) (3.43 g, 20.8 mmole) in 20 ml methylene chloride was treated with 1.5 equivlents (2.5 ml) thionyl chloride and the mixture stirred under nitrogen for two hours. The volatiles were removed in vacuo and the residue partitioned between methylene chloride and water. The aqueous layer was adjusted to pH 7.5 and extracted with fresh methylene chloride. The combined extracts were washed with water, brine, dried (Na₂SO₄) and solvent evaporated in vacuo to yield 3.28 g (86%) of the desired product which was used in the next step. (iii) The product from Part (ii) (3.28 g, 17.9 mmole) was dissolved in 30 ml toluene and 4.69 g (17.9 mmole) triphenylphosphine was added. The mixture was stirred at reflux for three hours, then at room temperature for 12 hours. The product was isolated by filtration, washing with toluene to afford 3.89 g (49%) of the desired Wittig reagent. PREPARATION D Allyl 6-alpha-bromo-1,1-dioxopenicillanate (i) 6-alpha-Bromopenicillanic acid 1,1-dioxide A suspension of 20.26 g (0.0517 mole) 6,6-dibromopenicillanic acid 1,1-dioxide in 80 ml water was treated in portions with 13 g (0.155 mole) of solid sodium bicarbonate. The vigorous gas evolution was controlled by addition of ethyl acetate. Solid sodium bisulfite 6.76 g (0.062 mole) was then added in portions, the resulting mixture stirred for 35 minutes and adjusted to pH 1.0 with concentrated hydrochloric acid. The acidified mixture was diluted with ethyl acetate, the organic phase washed with brine, dried (Na₂SO₄) and solvent evaporated in vacuo . The residue was triturated with chloroform and filtered to give 6.72 g pale yellow solid. Another 3.2 g of product was obtained by concentrating the filtrate and treating the residue with chloroform. (ii) To 6.352 g of the first crop material from above in 20 ml dimethylformamide was added 1.76 ml (20.3 mmole) allyl bromide, 2.83 ml (20.3 mmole) triethylamine and 0.2 g sodium bicarbonate and the mixture stirred under nitrogen at room temperature for 15 hours. Water was added, the mixture extracted with ethyl ether, the extracts washed with water, dried (Na₂SO₄) and solvent evaporated in vacuo to yield 4.60 g (64%) of the desired ester as an oil. ¹H-NMR(CDCl₃)ppm (delta): 1.4 (s, 3H), 1.6 (s, 3H), 4.4 (s, 1H), 4.6 (d, 1H), 4.7 (d, 2H), 5.15 (d, 1H), 5.1-5.95 (m, 3H). (iii) Allyl 6,6-dibromopenicillanate Esterification of 6,6-dibromopenicillanic acid by the above procedure on a 0.417 molar scale gave 140 g (84%) of allyl ester as an oil. ¹H-NMR(CDCl₃)ppm (delta): 1.5 (s, 3H), 1.65 (s, 3H), 4.6 (s, 1H), 4.75 (m, 2H), 5.3-5.6 (m, 2H), 5.85 (s, 1H), 5.8-6.3 (m, 1H). PREPARATION E 2-Formyl-1-methylimidazole (i) 2-Hydroxymethyl-1-methylimidazole A mixture of 50 g 1-methylimidazole and 100 ml 37% formaldehyde (sp. gr. 1.08) was placed in a stainless steel bomb (300 ml) and heated at 150° C. (bath temperature) for 17 hours. The bomb was then cooled in ice and the mixture removed, concentrated in vacuo and the residue stored at 4° C. overnight. The resulting mixture of crystals and oil was filtered, washing with ethyl acetate. The colorless crystals were dried in vacuo to afford 14.60 g of product. A second crop amounting to 6.48 g was obtained by reworking the mother liquor. Total yield 21.08 g (31%). (ii) To a solution of 4.96 g (43.9 mmole) 2-hydroxymethyl-1-methylimidazole in 50 ml dioxane was added 4.90 g (44.1 mmole) selenium dioxide and the mixture stirred at 85-90° C. for five hours, at room temperature for 36 hours, at 85° C. for eight hours and finally at room temperature for 15 hours. The reaction mixture was filtered, the solvent evaporated in vacuo to yield 4.81 g of crude aldehyde which was distilled to give 2.11 g of product as colorless crystals, b.p. 65° C. at 2.8 mm Hg. PREPARATION F 6-Methyl-2-pyridylmethyltriphenylphosphonium Chloride (i) 6-Methyl-2-hydroxymethylpyridine 6-Methylpyridine-2-carboxaldehyde (0.44 mmole) in 50 ml methanol was reduced with 20.6 mmole sodium borohydride at 0-5° C. After reduction was complete, the mixture was neutralized (pH 7.5) with 2N sulfuric acid, filtered, the filtrate concentrated band partitioned between chloroform and water. Evaporation of solvent from the organic layer gave 3.32 g of red-black oil which was used in the next step. (ii) 2-Chloromethyl-6-methylpyridine The above product 3.32 g (0.27 mmole) in 20 ml methylene chloride was treated with 1.94 ml (27 mmole) thionyl chloride at room temperature for one hour. The mixture was neutralized (NaHCO₃) and extracted with chloroform. Evaporation of solvent gave 3.22 g of product as an oil which was used in the next step. (iii) A solution of 3.22 g of the oil from Part (ii), 5.96 g triphenylphosphine in 30 ml toluene was heated at reflux for four hours. Filtration of the precipitate gave 3.93 g of the Wittig reagent as a brown solid. PREPARATION G 2-Pyrazinylmethyltriphenylphosphonium Chloride (i) 2-Hydroxymethylpyrazine To a solution of 11.29 g (79.2 mmole) 2-pyrazinecarbonyl chloride (prepared by treating the corresponding 2-carboxylic acid with a molar excess of thionyl chloride at the reflux temperature) in 100 ml tetrahydrofuran at -78° C. was added in portions over 20 minutes, 2.0 g 52.6 mmole of lithium aluminum hydride (95% pure). The mixture was stirred 10 minutes and allowed to warm to room temperature. The reaction was quenched with 2M sodium hydroxide, filtered, washing with methanol. Concentration of the filtrate in vacuo gave 4.12 g of dark solid which was used in the next step. (ii) The above dark solid (4.12 g, 37.8 mmole) was dissolved in methylene chloride and 2.8 ml of thionyl chloride added at 0° C. The mixture was warmed to room temperature, stirred for 30 minutes, water added, the mixture neutralized and extracted with methylene chloride to afford 2.29 g of yellow oil which was used in the next step. (iii) To the above oil, 2.29 g, in 40 ml toluene was added 4.70 g triphenylphosphine and the mixture refluxed for three hours. Work up in the usual manner gave 1.995 g Wittig reagent as a brown solid. PREPARATION H 4-Formylpyrimidine A solution of 4-methylpyrimidine (10 g, 0.106 mole) in 100 ml dioxane was treated with 11.8 g selenium dioxide at room temperature and the mixture was heated at 100° C. for 15 hours. After adding 2.5 g selenium dioxide, heating was continued one hour, the mixture cooled, filtered, and the cake washed with ethyl acetate. The filtrate and washings were evaporated to dryness in vacuo . The residual dark oil was taken up in methylene chloride, filtered and the solvent evaporated. The residue was crystallized from a small amount of methylene chloride to provide the title aldehyde. ¹H-NMR(CDCl₃)ppm (delta): 7.87 (dd, 1H), 9.06 (d, 1H), 9.43 (d, 1H), 10.0 (s, 1H) PREPARATION I Diphenylmethyl 6-alpha-bromo-1,1-dioxopenicillanate To a solution of 21.557 g (0.1 mole) diphenyldiazomethane in 400 ml dry tetrahydrofuran was added in portions over 30 minutes 31.2 g (0.1 mole) 6-alpha-bromo-1,1-dioxopenicillanic acid. The reaction was slightly exothermic. The mixture was stirred one hour, the solvent evaporated and the residue dissolved in ethyl acetate (50 ml). Ethyl ether (400 ml) was added and the resulting mixture was stored at 4° C. No crystal formed after 18 hours. The mixture was then concentrated in vacuo to yield 51.2 g yellow solid which was chromatographed on silica gel, eluting with chloroform to yield 14.86 g colorless product as a glass. ¹H-NMR(CDCl₃)ppm (delta): 1.26 (s, 3H), 1.57 (s, 3H), 4.55 (s, 1H), 4.70 (d, 1H), 5.13 (d, 1H), 6.9 (s, 1H), 7.27 (s, 10H). PREPARATION K Pyrazine-2-carboxaldehyde Pyrazine-2-carboxylic acid was esterified with methanolic sulfuric acid at reflux for five hours. The methanol was evaporated in vacuo , diluted with methylene chloride and neutralized with sodium bicarbonate (pH 7.5). The dried organic layer was concentrated to afford methyl pyrazine-2-carboxylate as an off-white solid in 84% yield which was recrystallized from isopropanol, ethyl ether to give yellow needles. ¹H-NMR(CDCl₃)ppm (delta): 4.1 (s, 3H), 8.93 (m, 2H), 9.47 (m, 1H). The methyl ester, 20 g (0.145 mole) was dissolved in 600 ml dry tetrahydrofuran, cooled to -78° C. and a solution of 5.8 g of 98% lithium aluminum hydride in THF was added dropwise over 15 minutes. The mixture was stirred for 30 minutes at -78° C., 20 ml acetic acid added and the mixture concentrated under reduced pressure. The residue was partitioned between 2N hydrochloric acid (30 ml) and chloroform, the combined organic layers washed with water, dried and evaporated to afford 8.53 g of crude product which was purified by passing it through a silica gel column, eluting with 4:1 methylene chloride/ethyl acetate to yield 5.02 g of light yellow needles. ¹H-NMR(CDCl₃)ppm (delta): 8.38 (m, 2H), 8.7 (bs, 1H), 9.7 (s, 1H). PREPARATION L 2-Phenyl-1,2,3-triazole-4-carboxaldehyde (i) Reaction of 0.34 mole acetone dicarboxylic acid in 100 ml water with 0.58 mole sodium nitrite at 0-10° C. and subsequent addition of dilute nitric acid to precipitate the product gave a 46% yield of the dioxime, 1,3-dioximino-2-oxopropane as tan crystals. (ii) The dioxime, (0.158 mole) in ethanol (170 ml) was reacted with equimolar amounts of phenylhydrazine hydrochloride and sodium acetate at 70° C. for 30 minutes. Water (170 ml) was added, the mixture heated to 85° C. reduced in volume to 250 ml and cooled to yield 24.7 g of the phenylhydrazone. ¹H-NMR(CD₃COCD₃)ppm (delta): 7.3 (m, 5H), 7.9 (s, 1H), 8.6 (s, 1H), 10.5 (bs, 1H), 11.4 (bs, 1H), 12.3 (s, 1H). (iii) The above dioximephenylhydrazone, 24.7 g (0.119 mole) was stirred at room temperature with 500 ml of acetic anhydride for 30 minutes and the mixture poured into water, stirred 20 minutes and filtered. The resulting crude solid was recrystallized from benzene/ethyl acetate to afford 15.47 g (52%) of the monoacetate, HON=CH-C(=NNHC₆H₅)CH=NOCOCH₃, as a yellow powder. ¹H-NMR(CDCl₃, acetone): 1.85 (s, 3H), 7.09 (m, 5H), 7.95 (s, 1H), 8.3 (s, 1H), 10.9 (bs, 1H), 12.25 (s, 1H). (iv) A solution of 15.40 g (0.062 mole) of the monoacetate, obtained above, and 22.16 g (0.068 mole) cesium carbonate in 400 ml tetrahydrofuran was stirred at room temperature for one hour, filtered and the filtrate concentrated to afford a yellow residue. The residue was dissolved in 700 ml hot 1:2 isopropyl ether/cyclohexane and concentrated to 200 ml to afford 9.41 g (80%) of 2-phenyl-1,2,3-triazole-4-carboxaldehyde oxime as a yellow powder which was used in the next step. (v) A mixture of the oxime, 9.41 g (0.0497 mole), 4.48 g s-trioxane and 300 ml 2N hydrochloric acid was heated at reflux for 3.5 hours. The aqueous phase was extracted with ethyl ether, the combined ether layers washed with water, dried (MgSO₄) and the ether evaporated in vacuo to yield 6 g of crystalline aldehyde. ¹H-NMR (CDCl₃)ppm (delta): 7.6 (m, 3H), 8.25 (m, 3H), 10.25 (s, 1H); m.p. 66-67° C. PREPARATION M 5-Methylisoxazol-3-carboxaldehyde (i) Ethyl 5-methylisoxazol-3-carboxylate A mixture of 0.16 mole ethyl 2,4-dioxovalerate and 0.08 mole hydroxylamine sulfate, 50 ml ethanol and 70 ml toluene was stirred at 40° C. for four hours. The mixture was cooled to 15-20° C., 1.8 g of concentrated ammonium hydroxide added and stirring continued at room temperature for 60 hours. The mixture was poured into water/toluene, the aqueous layer extracted with toluene, the organic layers combined, washed with brine and dried (Na₂SO₄). Evaporation of solvent in vacuo gave a yellow liquid which was distilled to afford 14.68 g of product, b.p. 120-124° C. at 30 torr which crystallized upon standing. (ii) The ethyl ester obtained above, 2.0 g (14.4 mmole), in 75 ml toluene was reduced with an equimolar amount of 1M diisobutylaluminum hydride in hexane under nitrogen at -75 to -70° C. After stirring for 30 minutes, the reaction was quenched with ammonium chloride solution, warmed to room temperature and the solvent evaporated in vacuo . The residue was triturated with hot methanol, evaporated to afford 0.85 g of product as a colorless oil. ¹H-NMR(CDCl₃)ppm (delta): 2.4 (s, 3H), 6.3 (d, 1H), 9.0 (s, 1H).

Claims: Claims for the following Contracting States: BE, CH, DE, FR, GB, IT, LI, LU, NL, SE A compound of the formula wherein n is zero, 1 or 2; R¹ is R a or R b where R a is the residue of a carboxy protecting group selected from tetrahydropyranyl, allyl, benzyl, 4-nitrobenzyl, benzhydryl, 2,2,2-trichloroethyl, t -butyl and phenacyl; and R b is hydrogen or the residue of an ester group readily hydrolyzable in vivo selected from 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, where R⁴ and R⁵ are each hydrogen or CH₃, R⁶ is (C₁-C₅)alkyl, and R¹⁴ is where R¹⁵ is 2-phenylacetamido, 2-phenoxyacetamido, D-2-amino-2-phenylacetamido, D-2-amino-2-(4-hydroxyphenyl)acetamido, 2-carboxy-2-phenylacetamido, 2-carboxy-2-(2-thienyl)acetamido, 2-carboxy-2-(3-thienyl)acetamido, D-2-(4-ethyl-2,3-dioxopiperazinocarbonylamino)-2-phenylacetamido or 2,2-dimethyl-4-phenyl-5-imidazolidinone-1-yl; one of R² and R³ is hydrogen and the other is CH₂OH, vinyl, (C₁-C₄)alkylthio, (C₁-C₄)alkylsulfonyl, furyl, thienyl, N-methylpyrrolyl, N-acetylpyrrolyl, R⁷C₆H₄, R⁷C₆H₄S, -CH(R⁴)NR¹⁶R¹⁷, and m is 2 or 3, p is zero or 1, t is zero, 1 or 2, X₁ is S, O or NR¹¹, R⁷ is hydrogen, (C₁-C₄)alkyl, (C₁-C₄)alkoxy, allyloxy, hydroxyl, carboxyl, (C₂-C₅)alkoxycarbonyl, (C₁-C₅)alkylcarbonyl, phenyl, benzyl, naphthyl, pyridyl, NR⁸R⁹, CONR⁸R⁹, NHCOR¹⁰, NO₂, Cl, Br, CF₃ or SR⁸; R⁸ and R⁹ are each hydrogen, (C₁-C₄)alkyl, phenyl or benzyl; R¹⁰ is (C₁-C₄)alkyl, CF₃ or phenyl; and R¹¹ is hydrogen, CH₃, C₂H₅ or CH₃CO; R¹⁶ and R¹⁷ are each H, (C₁-C₄)alkyl, (C₂-C₄)hydroxyalkyl, or taken together with the nitrogen atom to which they are attached R¹⁶ and R¹⁷ form a pyrrolidino, piperidino, morpholino, thiomorpholino or 4-methylpiperazino group; or a pharmaceutically acceptable acid addition salt of said compound where R² or R³ contains a basic nitrogen atom, or a pharmaceutically acceptable cationic salt of said compound wherein R¹ is hydrogen or R² or R³ contains a carboxyl group. A compound according to claim 1 wherein n is 2, one of R² and R³ is H and the other is 2-pyridyl, 2-quinolyl, 3-allyloxy-2-pyridyl, 3-methoxy-2-pyridyl, 4-methoxy-2-pyridyl, 3-hydroxy-2-pyridyl, 6-methyl-2-pyridyl, 1-methyl-2-imidazolyl, 2-thiazolyl, 4,5-dimethyl-2-thiazolyl, 4-methyl-2-thiazolyl, 4-pyrimidinyl, 2-pyrimidinyl, 4,6-dimethyl-2-pyrimidinyl, 2-pyrazinyl, 2-methyl-1,2,4-triazol-3-yl or benzothiazol-2-yl. A compound according to claim 2 wherein one of R² and R³ is H and the other is 2-pyridyl, 3-allyl-oxy-2-pyridyl, 2-pyrazinyl, 2-pyrimidinyl, 3-hydroxy-2-pyridyl, 4-methoxy-2-pyridyl or 2-thiazolyl. A compound of the formula wherein n is zero, 1 or 2; X₃ is H or Br, R¹ is R a or R b where R a is the residue of a carboxy protecting group selected from tetrahydropyranyl, allyl, benzyl, 4-nitrobenzyl, benzhydryl, 2,2,2-trichloroethyl, t-butyl and phenacyl; and R b is H or the residue of an ester group readily hydrolyzable in vivo selected from 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, where R⁴ and R⁵ are each hydrogen or CH₃, R⁶ is (C₁-C₅)alkyl, R¹⁴ is where R¹⁵ is 2-phenylacetamido, 2-phenoxyacetamido, D-2-amino-2-phenylacetamido, D-2-amino-2-(4-hydroxyphenyl)acetamido, 2-carboxy-2-phenylacetamido, 2-carboxy-2-(2-thienyl)acetamido, 2-carboxy-2-(3-thienyl)acetamido, D-2-(4-ethyl-2,3-dioxopiperazinocarbonylamino)-2-phenylacetamido or 2,2-dimethyl-4-phenyl-5-imidazolidinone-1-yl; and R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl, pyrazinecarbonyl, benzoyl, CF₃CO or CONR⁸R⁹; one of R¹² and R¹³ is hydrogen and the other is vinyl, (C₁-C₄)alkylsulfonyl, furyl, thienyl, N-methylpyrrolyl, N-acetylpyrrolyl, CH(R⁴)NR¹⁶R¹⁷, and m is 2 or 3, p is zero or 1, t is zero, 1 or 2, X₁ is S, O or NR¹¹; R⁷ is hydrogen, (C₁-C₄) alkyl, (C₁-C₄) alkoxy, allyloxy, hydroxy, carboxyl, (C₂-C₅) alkoxycarbonyl, (C₁-C₅) alkylcarbonyl, phenyl, benzyl, napthyl, pyridyl, NR⁸R⁹, CONR⁸R⁹, NCHOR¹⁰, NO₂, Cl, Br, CF₃ or SR⁸; and R⁸ and R⁹ are each H, (C₁-C₄)alkyl; phenyl or benzyl; R¹⁰ is (C₁-C₄)alkyl, CF₃ or phenyl; and R¹¹ is H, CH₃, C₂H₅ or CH₃CO; R¹⁶ and R¹⁷ are each H, (C₁-C₄)alkyl, (C₂-C₄)-hydroxyalkyl or taken together with the nitrogen atom to which they are attached R¹⁶ and R¹⁷ form a pyrrolidino, piperidino, morpholino, thiormorpholino or 4-methyl-piperazino group; or a pharmaceutically acceptable acid addition salt of said compound where R¹² or R¹³ contains a basic nitrogen atom or a pharmaceutically acceptable cationic salt of said compound wherein R¹ is H or R¹² or R¹³ contains a carboxyl group, provided that when R¹² or R¹³ is and p is zero, then R⁷ is other than H or CH₃; provided further that when n is 2, R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl or benzoyl and R¹² or R¹³ is then t is not zero, R⁷ is other than H or CH₃; and provided further that when n is 2, R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl or benzoyl, then R¹² or R¹³ is not provided further that when n=0 and R¹ is hydrogen, allyl, benzyl, benzhydryl or t -butyl, R¹⁸ is hydrogen and one of R¹² and R¹³ is hydrogen then the other of R¹² and R¹³ is not thienyl, furyl, pyridyl, quinolinyl or indolyl, or pyridyl, quinolinyl, pyrrolyl or indolyl substituted by an alkyl group. A compound according to claim 4 wherein n is zero or 2, one of R¹² and R¹³ is H and the other is 2-thiazolyl, 3-isothiazolyl, 5-methyl-3-oxazolyl, 1,3,4-thiadiazol-2-yl, pyridazin-3-yl, 1,2,3-thiadiazin-4-yl, 1,2,4-oxadiazin-3-yl, 1,2,4-oxadiazin-5-yl, 1,3,4-oxadiazin-2-yl 1-phenyl-5-methyl-1,2,3-triazin-4-yl, N-methyl-1,2,3,4-tetrazine-5-yl, 1-methyl-1,2-diazin-3-yl, 4-pyrimidiinyl, 4,5-dimethylthiazol-2-yl, benzothiazol-2-yl or 1-benzylbenzimidazol-2-yl; and R¹⁸ is H or CH₃CO. A compound according to claim 5 wherein X₃ is H, one of R¹² and R¹³ is H and the other is 2-thiazolyl or benzothiazol-2-yl. A compound according to claim 1 or claim 4 wherein R a is allyl or benzyl. A compound according to claim 1 or claim 4 wherein R b is H, a pharmaceutically acceptable cationic salt thereof, A pharmaceutical composition for treating bacterial infections which comprises in a weight ratio of 1:3 to 3:1 a compound of claim 8 and a beta-lactam antibiotic. A pharmaceutical composition for treating bacterial infections which comprises a pharmaceutically acceptable carrier and a compound according to claim 1 or claim 4 wherein R¹ is R b and R b is Claims for the following Contracting State: AT A process for preparation of a compound of the formula wherein n is zero, 1 or 2; R¹ is R a or R b where R a is the residue of a carboxy protecting group selected from tetrahydropyranyl, allyl, benzyl, 4-nitrobenzyl, benzhydryl, 2,2,2-trichloroethyl, t -butyl and phenacyl; and R b is hydrogen or the residue of an ester group readily hydrolyzable in vivo selected from 3-phthalidyl, 4-crotonolactonyl, gamma-butyrolacton-4-yl, where R⁴ and R⁵ are each hydrogen or CH₃, R⁶ is (C₁-C₅)alkyl, and R¹⁴ is where R¹⁵ is 2-phenylacetamido, 2-phenoxyacetamido, D-2-amino-2-phenylacetamido, D-2-amino-2-(4-hydroxyphenyl)acetamido, 2-carboxy-2-phenylacetamido, 2-carboxy-2-(2-thienyl)acetamido, 2-carboxy-2-(3-thienyl)acetamido, D-2-(4-ethyl-2,3-dioxopiperazinocarbonylamino)-2-phenylacetamido or 2,2-dimethyl-4-phenyl-5-imidazolidinone-1-yl; one of R² and R³ is hydrogen and the other is CH₂OH, vinyl, (C₁-C₄)alkylthio, (C₁-C₄)alkylsulfonyl, furyl, thienyl, N-methylpyrrolyl, N-acetylpyrrolyl, R⁷C₆H₄, R⁷C₆H₄S, -CH(R⁴)NR¹⁶R¹⁷, and m is 2 or 3, p is zero or 1, t is zero, 1 or 2, X₁ is S, O or NR¹¹, R⁷ is hydrogen, (C₁-C₄)alkyl, (C₁-C₄)alkoxy, allyloxy, hydroxyl, carboxyl, (C₂-C₅)alkoxycarbonyl, (C₁-C₅)alkylcarbonyl, phenyl, benzyl, naphthyl, pyridyl, NR⁸R⁹, CONR⁸R⁹, NHCOR¹⁰, NO₂, Cl, Br, CF₃ or SR⁸; R⁸ and R⁹ are each hydrogen, (C₁-C₄)alkyl, phenyl or benzyl; R¹⁰ is (C₁-C₄)alkyl, CF₃ or phenyl; and R¹¹ is hydrogen, CH₃, C₂H₅ or CH₃CO; R¹⁶ and R¹⁷ are each H, (C₁-C₄)alkyl, (C₂-C₄)hydroxyalkyl, or taken together with the nitrogen atom to which they are attached R¹⁶ and R¹⁷ form a pyrrolidino, piperidino, morpholino, thiomorpholino or 4-methylpiperazino group; or a pharmaceutically acceptable acid addition salt of said compound where R² or R³ contains a basic nitrogen atom, or a pharmaceutically acceptable cationic salt of said compound wherein R¹ is hydrogen or R² or R³ contains a carboxyl group; characterized in that a starting compound of the formula wherein R¹ is as defined above, preferably R a , is reacted with a Wittig reagent of the formula R²R³C=P(C₆H₅)₃ in the presence of a reaction inert organic solvent, at a temperature in the range of from -100 to +50° C. to provide a compound of formula (I) wherein n is zero; and when compounds of formula (I) wherein n is 1 or 2 are desired, oxidation of said compound wherein n is zero, preferably by means of an alkali metal or alkaline earth permanganate, 3-chloroperbenzoic acid or peracetic acid; and when compounds of formula (I) wherein R¹ is R b are desired, removal of said carboxy protecting group, R a , to provide a compound of formula (I) wherein R¹ is H and, if desired, subsequent reaction with a compound of the formula R b Q, wherein R b is other than hydrogen as defined above and Q is chloro, bromo or iodo, in the presence of a polar organic solvent. A process for preparation of a compound of the formula wherein n is zero or 2, X³ is H or Br, R¹ is as defined in claim 1, R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl, pyrazinecarbonyl, benzoyl, CF₃CO or CONR⁸R⁹; one of R¹² and R¹³ is hydrogen and the other is vinyl, (C₁-C₄)alkylsulfonyl, furyl, thienyl, N-methylpyrrolyl, N-acetylpyrrolyl, CH(R⁴)NR¹⁶R¹⁷, and m is 2 or 3, p is zero or 1, t is zero, 1 or 2, X₁ is S, O or NR¹¹; R⁷ is hydrogen, (C₁-C₄) alkyl, (C₁-C₄) alkoxy, allyloxy, hydroxy, carboxyl, (C₂-C₅) alkoxycarbonyl, (C₁-C₅) alkylcarbonyl, phenyl, benzyl, naphthyl, pyridyl, NR⁸R⁹, CONR⁸R⁹, NHCOR¹⁰, NO₂, Cl, Br, CF₃ or SR⁸; and R⁸ and R⁹ are each H, (C₁-C₄)alkyl; phenyl or benzyl; R¹⁰ is (C₁-C₄)alkyl, CF₃ or phenyl; and R¹¹ is H, CH₃, C₂H₅ or CH₃CO; R¹⁶ and R¹⁷ are each H, (C₁-C₄)alkyl, (C₂-C₄)hydroxyalkyl or taken together with the nitrogen atom to which they are attached R¹⁶ and R¹⁷ form a pyrrolidino, piperidino, morpholino, thiomorpholino or 4-methylpiperazino group; or a pharmaceutically acceptable acid addition salt of said compound where R¹² or R¹³ contains a basic nitrogen atom or a pharmaceutically acceptable cationic salt of said compound wherein R¹ is H or R¹² or R¹³ contains a carboxyl group; provided that when the compound is of formula (I') R¹² or R¹³ is not a substituted or unsubstituted N-oxypyrrolyl or N-oxoquinolyl, provided that when n is 2, R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl or benzoyl, R¹² or R¹³ is and p is zero, then R⁷ is other than H or CH₃; provided further that when n is 2, R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl or benzoyl and R¹² or R¹³ is then t is not zero, R⁷ is other than H or CH₃; and provided further that when n is 2, R¹⁸ is H, (C₂-C₅)alkanoyl, (C₂-C₅)alkoxycarbonyl or benzoyl, then R¹² or R¹³ is not provided further that when n=0 and R¹ is hydrogen, allyl, benzyl, benzhydryl or t -butyl, R¹⁸ is hydrogen and one of R¹² and R¹³ is hydrogen then the other of R¹² and R¹³ is not thienyl, furyl, pyridyl, quinolinyl or indolyl, or pyridyl, quinolinyl, pyrrolyl or indolyl substituted by an alkyl group; characterized in that a compound of the formula wherein R¹ is other than H and n is zero or 2, is contacted with equimolar amounts of a (C₁-C₄)alkyl-magnesium halide or a (C₁-C₄)alkyl-lithium reagent, and an aldehyde of the formula R¹²R¹³CO, wherein said halide is Cl, Br or I and R¹² and R¹³ are as defined above, in the presence of a reaction inert solvent at a temperature of from -100 to +25° C., to provide a compound of the formula and when compounds of the formula (II) wherein R¹⁸ is other that H and X₃ is Br are desired, conversion of said compound (XI) to a carboxy protected derivative wherein R¹ is R a as defined above, and acylation with an acyl chloride or acyl bromide of the formula R¹⁸Cl or R¹⁸Br or a corresponding acid anhydride in the presence of an equimolar amount of tertiary amine, and in the presence of a reaction inert organic solvent; and when compounds of the formula (II) wherein X₃ is H are desired, hydrogenolysis of a compound of formula (II), X₃ is Br, in the presence of a reaction inert solvent with an organotin hydride or with hydrogen in the presence of a noble metal catalyst; and when compounds of formula (I') are desired, dehydration or deacetylation of a compound of formula (II), where X₃ is H and R¹⁸ is H or acetyl. A process for preparation of a compound of the formula wherein R¹, R¹², R¹³ and R¹⁸ are as defined in claim 2, characterized in that a compound of the formula wherein R¹ is other than H, is reacted with an equimolar amount of a (C₁-C₄)alkylmagnesium halide in an ethereal solvent at a temperature of from -80 to 25° C., to provide a first product of the formula and when compounds of formula (II') wherein R¹⁸ is other than H are desired, reaction of said first product with an acyl chloride, acyl bromide of the formula R¹⁸Cl or R¹⁸Br or a corresponding acid anhydride, in the presence of an equimolar amount of tertiary amine and in the presence of a reaction inert organic solvent; and when compounds of the formula (VIII) are desired, dehydration of said first product, or deacetylation of a compound of formula (II') wherein R¹⁸ is acetyl. A process according to claim 1 wherein in said starting compound, R¹ is R a , preferably allyl or benzyl, said reaction inert solvent is tetrahydrofuran, said temperature is from -78 to 25° C., one of R² and R³ is H and the other is 2-pyridyl, 2-quinolyl, 3-allyloxy-2-pyridyl, 3-methoxy-2-pyridyl, 4-methoxy-2-pyridyl, 3-hydroxy-2-pyridyl, 6-methyl-2-pyridyl, 1-methyl-2-imidazolyl, 2-thiazolyl, 4,5-dimethyl-2-thiazolyl, 4-methyl-2-thiazolyl, 4-pyrimidinyl, 2-pyrimidinyl, 4,6-dimethyl-2-pyrimidinyl, 2-pyrazinyl, 2-methyl-1,2,4-triazol-3-yl or benzothiazol-2-yl; and said compound of formula (I) wherein n is zero is oxidized to a corresponding compound where n is 2 by oxidation with 3-chloroperbenzoic acid or potassium permanganate. A process according to claim 2 or claim 3 wherein said reaction with aldehyde, R¹²R¹³CO, is carried out at -78° C. in the presence of tetrahydrofuran or ethyl ether. A process according to claim 5 wherein one of R¹² and R¹³ is H and the other is 2-thiazolyl, 3-isothiazolyl, 5-methyl-3-oxazolyl, 1,3,4-thiadiazol-2-yl, pyridazin-3-yl, 1,2,3-thiadiazin-4-yl, 1,2,4-oxadiazin-3-yl, 1,2,4-oxadiazin-5-yl, 1,3,4-oxadiazin-2-yl, 1-phenyl-5-methyl-1,2,3-triazin-4-yl, N-methyl-1,2,3,4-tetrazine-5-yl, 1-methyl-1,2-diazin-3-yl, 4-pyrimidinyl, 4,5-dimethylthiazol-2-yl, benzothiazol-2-yl or 1-benzylbenzimidazol-2-yl. A process according to claim 2 or claim 6 wherein a compound of formula (X) where in R¹ is allyl or benzyl is reacted with methylmagnesium bromide and an aldehyde of formula R¹²R¹³CO, and a product of formula (II) wherein X₃ is H is obtained by hydrogenolysis with tri-n-butyltin hydride in benzene or toluene as solvent at a temperature of from 0° C. up to the boiling point of the solvent. A process according to claim 1 wherein one of R² and R³ is H and the other is 2-pyridyl, 3-allyloxy-2-pyridyl, 2-pyrazinyl, 2-pyrimidinyl, 3-hydroxy-2-pyridyl, 4-methoxy-2-pyridyl or 2-thiazolyl. A process according to claim 6 wherein one of R¹² and R¹³ is H and the other is 2-thiazolyl or benzothiazol-2-yl. A process according to any of the preceding claims wherein in said starting compound R¹ is allyl and said allyl group is converted to a corresponding compound wherein R¹ is H, Na or K by reacting the allyl ester product obtained in the presence of a reaction inert solvent with catalytic amounts of tetrakis (triphenylphosphine)palladium(O) and triphenylphosphine and an equimolar amount of the sodium or potassium salt of 2-ethylhexanoic acid.

Inventors: CHEN, YUHPYNG LIANG
Applicants: PFIZER INC.
Application year: 1985
Main classification: C07D499
IPC codes: C07D261, C07D249, C07D241, C07D213, C07F9, C07D277, C07D499, C07D233, C07D239