WO1993000346A1 - Cephalosporin derivatives - Google Patents

Abstract

New antibacterially-active cephalosporins are disclosed having either two carboxyl groups, two protected carboxyl groups, or salts thereof, substituted at the carbon atom in the four position of the dihydrothiazine ring.

Description

CEPHALOSPORIN DERIVATIVES

Background of the Invention ^β-lactam antibiotics are a family of natural and synthetic products whose members are of medicinal interest as antibacterial agents. The β-lactam ring is a four-membered ring containing an amide bond, and it is the common structural feature of the antibiotics commonly known as penicillins and cephaiosporins. These antibiotics function by interfering with the integrity of bacterial cell walls by binding to one or more of a group of bacterial enzymes termed "penicillin-binding proteins" (PBPs) . These enzymes serve to complete bacterial cell wall synthesis and are essential to the survival of the bacteria. Most bacteria contain between 1.000 and 10,000 total PBPs per cell, and they comprise approximately one percent of the total membrane protein. Any given PBP varies greatly in its relative abundance. For example, in E. coli. PBP-2 accounts for approximately one percent of the organism's penicillin-binding activity, as compared to approximately 90% of the total penicillin-binding activity for PBP-5 of Bacillus s earothermophilus.

SUBSTITUTE SHEET -2-

The affinity of a PBP for a β-lactam antibiotic is usually expressed as the concentration of antibiotic required to reduce [¹⁴C] penicillin-G binding to the PBP by 50%.

While there are many penicillin and cephalosporin derivatives, both naturally and synthetically occurring, not all of these have sufficient efficacy to become important in medicine.

The β-lactam compounds produced by the Penicillium species are the penicillins. These compounds are bicyclic, with a β-lactam ring, having an acylamino side chain, fused to a 5-membered thiazolidine ring. The compounds produced by the Cephalosporium species, called cephaiosporins, also contain a bicyclic nucleus. In these compounds, the β-lactam ring, with its acylamino side chain, is fused to a 6-membered dihydrothiazine ring, which also has a peripheral chain which can be chemically modified, along with the acylamino side chain, to produce products that do not occur naturally. Thousands of new penicillin and cephalosporin variants have been synthesized by varying the acylamino side chain on the β-lactam ring or the peripheral chain on the dihydrothiazine ring.

Summary of the Invention

This invention pertains to new cephaiosporins having antibacterial activity and having two carboxyl groups, protected carboxyl groups, or salts thereof, at the carbon atom in the four position of the dihydrothiazine ring. The cephaiosporins are useful for therapy or prophylaxis of bacterial infection.

SUBSTITUTE SHEET -3-

Detailed Description of the Invention

The cephaiosporins of this invention are non-naturally occurring β-lactam antibiotics. The cephaiosporins have antibacterial activity and contain two carboxyl groups, protected carboxyl groups, or salts thereof, substituted at the carbon atom at the four position of the dihydrothiazine ring (according to the conventional numbering system for cephaiosporins). The compounds are useful antibacterial agents

In a preferred embodiment, the cephaiosporins have the following general formula:

where M and M* are the same or different and may be H, a carboxyl protecting group hydrolyzable in vivo or an alkali metal;

Rj is a β-lactam side chain having active antibiotic properties;

R₂ is H, OR₆, SR₆, or NHCOR,, where R₆ and R₆ are H or lower alkyls having from 1-5 carbons;

X may be S, 0, or CH₂;

R₃ is H, a lower alkyl having from 1-5 carbons, aryl, halogen, OH, OR₈, SH, SR_e, NH₂, NHCOR_j or CH₂R₇;

R„ is H, a lower alkyl having from 1-5 carbons, vinyl, substituted vinyl, aryl, halogen, OH, OR_$, SH, SR_S, NH₂, NHCORj, or CH₂R₇;

SUBSTITUTE SHEET -4-

R₇ is OCOR_g, pyridinium, substituted pyridinium or aryl; and

R₈ is selected from the group consisting of H, NH₂, and lower alkyls having from 1-5 carbons.

R_t represents any of the known β-lactam active side chains or pharmaceutically acceptable salts thereof, β-lactam active side chains are acylamino chains known to be active in β-lactam antibiotics. As used herein, the acceptable substituents in β-lactam antibiotics may be any of the wide range of substituents disclosed in the literature for penicillins and cephaiosporins. Such substituents may, for example, include a group of the formula -XQ where X represents oxygen or sulfur and Q represents C_x_₄ alkyl (e.g., methyl or ethyl), C₂„ alkenyl (e.g., vinyl or propenyl) or aryl C-*_ alkyl (e.g., phenyl C_x_₄ alkyl such as benzyl) groups.

Such substituents also may be an unsaturated organic group such as a group of the formula:

wherein R₉ and R₁₀ may be the same or different, and are each selected from hydrogen, carboxy, cyano, C₂_₇ alkoxycarbonyl (e.g., methoxycarbonyl or ethoxycarbonyl) , and substituted or unsubstituted aliphatic (e.g., alkyl, preferably C_j-Cg alkyl such as methyl, ethyl, isopropyl or n-propyl) groups. Specific substituted vinyl groups of the above formula include 2-carboxyvinyl, 2-methoxycarbonylvinyl, 2-ethoxycarbonylvinyl and 2-cyanovinyl.

SUBSTITUTE SHEET -5-

Alternatively, the β-lactam acceptable substituent may also be an unsubstituted or substituted methyl group depicted by the formula:

-CH₂Y

wherein Y is a hydrogen atom or a nucleophilic atom or group, e.g., the residue of a nucleophile or a derivative of a residue of nucleophile. Y may thus, for example, be derived from the wide range of nucleophilic substances possessing a nucleophilic nitrogen, carbon, sulfur or oxygen atom. Such nucleophiles have been widely described in the patent and technical literature respecting β-lactam chemistry and are exemplified by Foxton fii al.. U.S. Patent No.

4,385,177.

Particularly preferred cephaiosporins of this invention are represented by the following general formula :

where R_α is a benzyl, substituted benzyl, phenoxymethyl or substituted phenoxymethyl and M and W are H, Na+ or K+, R₂ is H or OCH, and R, is H or CH..

UBSTiTUTE -6-

Cephalosporins of this invention can be synthesized by conventional procedures. In a preferred procedure, a penicillin serves as the starting compound. The penicillin may be selected to provide a desired aminoacyl side chain (or the desired aminoacyl side chain may be added at a later step as shown below) . A preferred penicillin is penicillin V, shown in the formula below. The acyl side chain is a phenoxyacetyl group.

Penicillin V

Penicillin G is another suitable starting compound. A synthesis employing penicillin as a starting compound is outlined below. The selected penicillin is converted by standard techniques to compound I:

SUBSTITUTE SHEET -7-

A preferred method for the conversion is described by Cooper and Jose (1972) J. A er. Chem. Soc. £4:1021.

Compound I is then reacted with dimethyl bromomalonate R₂0₂CCHBrC0₂R₂, or an analog thereof/ to yield compound II:

The dimethyl bromomalonate reagent can be prepared from R₁₁0₂CCH₂C0₂R₁₁, where R_X1 is a standard carboxylic acid protecting group, such as CH,, capable of surviving the later step that generates an aldehyde (or ketone) group (compound IV). As shown below, removing R_xl in the final step generates the carbon atom bearing the two carboxylic acid groups.

Compound II can be allylated by reaction with BrCHR₃CH=CH₂ to form compound III (see Long, A.G. "Conversion of Penicillins into β-Lactam Antibiotics of New Types" in Recent Advances in the Chemistry of β-Lactam Antibiotics ed. J. Elks, Burlington House, London (1977)):

SUBSTITUTE SHEET R₃ can be H or groups such as CH,, lower alkyls, aryl, heteroaryl, vinyl, substituted vinyl, or CH₂R , where R₄ = OH, SH, OCOR_j, SCOR_j, NH₂, or a halogen.

Alternatively, compound III may be formed by reacting compound II with the reagent a) BrCH₂CR',CH₂ or b) BrCHR,CR',CH₂, where R*, is defined as is R,, and may or may not be the same as R_s. These alternative pathways lead to the following compounds:

OR

SUBSTITUTE SHEET Using structure Illb in the next step, the double bond is oxidized, such by ozonolysis, to yield compound IV:

The thiazoline ring is then hydrolyzed to form compound V:

SUBSTITUTE SHEET -10-

The dehydration of compound V leads to compound VI:

The Rn group can be removed from compound VI to form a biologically active pharmaceutically acceptable salt of a cephalosporin, compound VII:

o

where M is Na⁺ or K⁺ .

If desired, the side chain RjCO can be removed from compound VI, for example, as described by G.R. Fosker, K.D. Hardy, V.H.C. Nayler, P. Seggery and E.R, Stover, J. Chem. Soc. C.. 1917 (1971), to afford the compound VIII:

SUBSTITUTE ET - -

Any of the common β-lactam side chains (symbolized by RjCO) and known to be efficacious in β-lactam compounds, may be attached by methods commonly known in the art prior to removal of R_1:t, leading to compound IX:

The 7-ρosition of the amine VIII, or of the diester having the structure:

SUBSTITUTE SHEET -12-

may also be functionalized by methods known to those skilled in the art, for example as described by E.M. Gordon and R.B. Sykes, in Chemistry and Bioloσv of β-Lactam Antibiotics. Edited by R.B. Morin and M. Gorman, Academic Press, New York, 1982, vol. 1, pp. 218, to yield the compounds XI or XII:

OR

SUBSTITUTE SHEET -13-

where R₂ is OR₈, SR₆ or NHCORj.

If R₃ is CH₂-halogen or CH₂-OAc, compounds VI, X or XII can be converted to compound XIII using methods commonly known to those skilled in the art, for example, using the method as described by S. Kukolja and R.R. Chauvette, in Chemistry and Bioloσv of β-Lactam Antibiotics, edited by R.R. Morin and M.G. Forman, Academy Press, New York, 1982, vol. 1, pp. 95-170, which leads to compound XIII:

After ozonolysis, this compound is converted to XIV:

SUBSTITUTE SHEET -14-

which can be converted to :

There is an alternative route for forming compound IV from compound II which bypasses the ozonolysis step shown in the conversion of compound Illb to compound IV above. This involves a Michael addition to an olefin of type XVI:

where R₃ and R'₃ are as already defined, to give compound XVII:

followed by a Nef reaction, for example, as described by F. Urpf and J. Vilarrasa, Tetrahedron Letters 31, 7499 (1990) to form compound IV.

The cephaiosporins of this invention have antibacterial activity and, as antibiotics, they may be used with any of the standard pharmaceutical vehicles for administration to a host organism. The actual amounts administered will vary according to usual factors, e.g., the specific compound utilized, the particular compositions formulated, the mode of application, and the particular situs and organism being treated. Dosages for a given host can be determined using conventional pharmaceutical procedures. The carboxyl groups can be protected by appropriate protecting groups, e.g., esters, hydrolyzable in vivo.

The invention is illustrated further by the following examples:

EXAMPLES

Example I

Step 1. Preparation of Dimethyl Bromomalonate

Freshly distilled dimethyl malonate (b.p. 68-69°/12 torr) (39.6 g, 0.3 mole), in 45 mL carbon tetrachloride, was treated with a few drops of a solution of bromine (15.9 mL, 0.309 mole) in carbon tetrachloride (40 mL) . There was no discernible reaction and the solution was therefore illuminated with a small reading lamp. After 10 minutes, the solution suddenly decolorized and became warm. The remainder of the bromine solution was then added dropwise over 1.5 hours, with a steady evolution of

SUBSTITUTE SHEET HBr, to yield a red reaction mixture which turned gold when refluxed for 20 minutes. The solution was cooled and washed successively with water (2 x 100 mL the organic layer became colorless), saturated sodium bicarbonate (1 x 50 mL), water (1 x 100 mL) and saturated sodium chloride (1 x 40 mL) dried over anhydrous calcium chloride, and evaporated. The residue is distilled at 12 torr. The central fraction, which boiled at 100.5-107"C, is distilled at 14 torr. The fraction of that second distillation boiling at 106-109° is retained for use in Step 2. ⁱHmr (CDC1₃, δ) : 3.85 (6H, s), 4.87 (1H, s) .

Step 2. Reaction of the Thiazoline-Azetidinone 1 with Dimethyl Bromomalonate

The thiazoline-azetidinone (1) prepared from penicillin V by the procedure of Cooper and Jose J. Amer. Chem. Soc. 21 1021 (1972) (1.146 g, 4.9 mmoles) was dissolved in freshly dried dimethylformamide (distillation from calcium hydride under reduced pressure) (12.0 mL), cooled to -30°C, and stirred under nitrogen while a 40% methanolic solution of Triton B (4.5 mL, 2-equiv, from a freshly opened bottle) was added dropwise over 10 minutes. The orange solution was stirred for 25 minutes at -30° to -35°C, for 30 minutes at 2^βC, and then again at -30°C for 30 minutes while dimethyl bromomalonate (0.68 mL,

SUBSTITUTE SHEE i 1.088 g, 5.1 mmoles) prepared in Step 1 is added dropwise. Stirring was continued for 15 minutes at -30°C, and then for 130 minutes at 2^βC, glacial acetic acid (1 mL) was added. The reaction mixture was poured into 10% potassium bisulfate (50 mL), and extracted with ethyl acetate (3 z 50 mL) . The combined organic phase is washed with 5% sodium chloride (6 x 50 mL), saturated sodium chloride (1 x 40 mL) , dried over anhydrous sodium sulfate and evaporated to give 1.79 g of malonylazetidinone 2, as an amber syrup which shows only one spot on thin layer chro atography (tic) (silica gel, elution with 19/1 methylene chloride/ethyl acetate). ^xHmr (CDC1₃, δ) : 3.74 (3H, s, CH,), 3.84 (3H, S, CH,), 4.91 (1H, d, 13.2 Hz, CHH), 5.00 (1H, d, 13.2 Hz, CHH) , 6.02 (1H, d, 4Hz. CH), 6.11 (1H, d, 4Hz, CH), 6.94-7.05 (3H, m, Ar), 7.31 (2H, t, Ar).; m/z 364 (M+) .

SUBSTITUTE SHEET -18-

Step 3. Allylation of the Malonvlazetidinone

The malonylazetidinone 2 (1.23 g, 3.38 mmoles) in dry dimethylformamide (5.0 mL) was stirred in an icebath under a strong stream of nitrogen and 80% sodium hydride (135 mg, 4.5 mmoles) was added through a funnel. The nitrogen flow was turned off to observe hydrogen evolution, and stirring was continued for 10 minutes at 2°C, and then for 60 minutes at 20°C. Additional dimethylformamide (2 mL) was added, the mixture was cooled to 2°C, and freshly distilled allyl bromide (b.p. 68-69°C, 950 μL) was added, dropwise. The reaction was allowed to warm to room temperature overnight, with continued stirring. Additional sodium hydride (30 mg) was then added and stirred for 30 minutes at room temperature after which an additional 100 μL allyl bromide was added. After 5 hours at room temperature the reaction was complete (tic) . The mixture was partitioned between ethyl acetate (50 mL) and water (100 mL) , and the organic layer was washed successively with water (3 x 100 mL) , saturated with sodium chloride (50 mL) , dried over anhydrous sodium sulfate, and evaporated to form a golden syrup, 1.33 g. This was purified on silica gel (10 g); elution with 2:1 hexane:ethyl acetate afforded 1.23 g of the allylated malonylazetidinone (3). ¹Hmr (CDC1₃, δ) : 3.07 (2H, dq, CH₂ of allyl), 3.76 (3H, s, CH,), 3.79

SUBSTITUTE SHEET -19-

(3H, s, CH₃), 4.86 (IH, d, 13.2 Hz, CHH), 4.97 (IH, d, 13.2 Hz, CHH), 5.14 (2H, m, «CH₂), 5.72 (IH, m, -CH) , 5.91 (IH, d, 4 Hz, CH), 6.00 (IH, d, 4 Hz, CH) , 6.94 (2H, d, Ar), 7.00 (IH, t, Ar) , 7.29 (2H, t, Ar) ; m/z:

Step 4a. To a solution of the allylated malonylazetidinone 3 (0.919 g, 2.27 mmoles) in methylene chloride (30 mL) and water (15 mL)* was added iodine (0.590 g, 4.65 mmoles). The mixture was stirred for 2.5 hours at room temperature and then diluted with methylene chloride (50 mL) . The aqueous layer was separated and the organic layer washed successively with saturated sodium bicarbonate (20 mL) containing sodium bisulfite (1 g) , and saturated sodium chloride (20 mL), dried over magnesium sulfate and evaporated to a yellow foam (1.20 g) . This was purified by flash chromatography (silica gel; hexane-ethyl acetate 3:2) to yield to products, the iodocepha 4a (0.39 g, 31%), and the seven membered ring A (0.51 g, 41%). The cepham 4a shows ¹Hmr (CDCL₃, δ): 2.01 (IH, d, 12 Hz), 2.04 (IH, d, 12 Hz), 2.73 (IH, dd, 2, 14 Hz), 2.94 (IH, m) , 3.18 (IH, dd, 8, 10 Hz), 3.27 (IH, dd, 5, 10 Hz), 3.84 (3H, s), 3.86 (3H, s), 4.53 (2H, s) , 5.38 (IH, d, 4 Hz), 5.81 (IH,

SUBSTITUTE SHEET -20-

dd, 4, 9 Hz), 6.90-7/35 (5H, m) . A aJL. Calcd. for C₁₉H₂₁N₂0₇SI: C, 41.62; H, 3.86; N, 5.11. Found: C, 41.81; H, 3.86; N, 5.02.

(3) (4a) (A)

Step 4b. The iodocepham 4a (0.383 g, 0.698 mmoles) was dissolved in methylene chloride (15 mL) and treated with diazabicycloundecene (DBU) (0.30 mL, 2.0 mmoles). The solution was refluxed for 6.5 hours and then cooled, diluted with methylene chloride (50 mL) , washed successively with 1M HC1 (10 mL) , water (10 mL) , saturated sodium bicarbonate (10 mL) and saturated sodium chloride (10 mL), dried over magnesium sulfate and evaporated. The product was dissolved in trifluoroacetic acid (2 mL) . This solutin was evaporated after 10 minutes and the residue purified by chromatography on silica gel (hexane-ethyl acetate 1:1) to yield the 2-methyl-2- cephe as a 1:1 mixture of 5 and 6, which are epimers at C7. Colorless foam, ¹Hmr (CDC1,, δ) : 2.02, 2.07 (3H, 2 doublets, 1.2 Hz), 3.83 (3H, ε), 3.86 (3H, s), 4.57 (2H, s), 4.82 (H6 of 6, d, 2 Hz), 5.10 (H7 of 6, dd, 2, 7 Hz), 5.33 (H6 of 5, d, 4 Hz), 5.7-6.0 (H7 of 5 and vinyl CH, 2H, m) , 6.9-7.5 (6H, m) .

SUBSTITUTE SHEET

(5)

Step 4c. The diesters 5 and 6, (168 mg, 0.400 mmole), a 1:1 mixture of C7 epimers were dissolved in dry tetrahydrofuran (3.5 mL) and stirred under nitrogen at -78°C. Then 1M lithium methoxide in raethanol (1.4 mL, 1.4 mmoles) was added, followed immediately by t-butyl hypochlorite (0.070 mL, 0.59 mmole). Stirring was continued for 20 minutes and the reaction was then quenched by the dropwise addition of acetic acid (0.40 mL, 7 mmoles) during 1 minute. After a further 2 minute, trimethylphosphite (0.05 mL, 0.42 mmole) was added to reduce excess hypochlorite and the reaction mixture was allowed to warm to room temperature. The mixture was then diluted with methylene chloride (60 mL) and washed successively with water (10 mL), saturated sodium bicarbonate (10 mL) and saturated sodium chloride (10 mL), dried over magnesium sulfate and evaporated to a light yellow oil. This was chromatographed to give 5 and its 7-methoxylated derivative 7.

7: ^lHmr (CDC1,, δ) : 1.97 (3H, s), 3.55 (3H, s), 3.77 (6H, s), 4.60 (2H, s), 5.34 (IH, s), 5.79 (IH, br s), 6.9-7.5 (5H, m), 7.70 (IH, br s) .

SUBSTITUTE SHEET

Step 4d. The diester 5 (8.3 mg, 0.0197 mmole), in pyridine (0.3 mL) was treated with 1M potassium hydroxide (43 μL) . After 18 hours, bioassay on &_ lutβus showed antibacterial activity at a level of 100 μg/ The ¹Hmr spectrum (D₂0, δ) shows a vinyl proton at 5.77, and the β-lactam protons at 5.45 (d, 4 Hz) and 5.19 (d, 4 Hz). The biologically active material has structure 8.

S

Step 4e. The methoxylated diester 7 (3.2 mg, 0.0071 mmole), in pyridine (0.3 mL) was treated with lM potassium hydroxide (15 μL) . After 30 minutes, the solvent was removed. The residue, assigned structure

SUBSTITUTE SHEE 9, exhibitied antibacterial activity on &__ luteus plates at a level of 100 μg. Its ¹Hmr spectrum in D₂0 shows the vinyl proton at 5.72 Hz, and the C6 proton as a singlet at 5.32.

fs

Equivalents

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the following claims.

SUBSTITUTE SHEET

Claims

Claims

1. A cephalosporin having antibacterial activity and having two carboxyl groups, protected carboxyl groups, or salts thereof, at the carbon atom in the four position of the dihydrothiazine ring.

2. A cephalosporin, or isomer thereof, of the formula:

wherein M is H, -a carboxyl protecting group hydrolyzable in vivo or an alkali metal; _x is a β-lactam side chain having active antibiotic, properties;

R₂ is selected from the group consisting of H, OR₅, SR_S, and NHC0R₆, and where R₅ is a lower alkyl having 1-5 carbons, and R₆ is selected from the group consisting of H and lower alkyls having 1-5 carbons;

X is selected from the group consisting of S, 0, and CH₂;

R₃ is selected from the group consisting of H, lower alkyl having 1-5 carbons, aryl, halogen, OH, OR₅, SH, SR₅, NH₂, NHCORj. and CH₂R₇;

SUBSTITUTE SHEET -25-

R₄ is selected from the group consisting of H, lower alkyl having 1-5 carbons, vinyl, substituted vinyl, aryl, halogen, OH, OR_e, SH, SR_S, NH₂, NHCOR , and CH₂R₇;

R₇ is selected from the group consisting of OCOR,, pyridinium, substituted pyridinium and aryl; and

R, is selected from the group consisting of NH₂, H, and lower alkyls having from 1-5 carbons.

3. A cephalosporin of claim 2, wherein R_x is -XQ, wherein X is 0 or S and Q is a lower alkyl having from 1-4 carbon atoms, a lower alkenyl having from 2-4 carbon atoms, or an arylalkyl having from 1-4 carbon atoms.

4. A cephalosporin of claim 2, wherein _x is benzyl or phenoxyacetyl.

5. The cephalosporin of claim 2, wherein R_x is CH₂Y, wherein Y is H or a nucleophilic group.

6. A cephalosporin having the formula:

where R_α is phenyl, substituted phenyl, phenoxy or substituted phenoxy and M is H, Na⁺ or K⁺, R. is H or OCH, and R, is H or CH,.

SUBSTITUTE SHEET A method of therapy or prophylaxis of bacterial infection, comprising administering an antibacterial amount of a cephalosporin having two carboxyl groups, protected carboxyl groups, or salts thereof, at the carbon atom in the four position of the dihydrothiazine ring.

A method of therapy or prophylaxis of bacterial infection, comprising administering an antibacterial amount of a cephalosporin of the formula:

wherein M is H, a carboxyl protecting group or an alkali metal; _α is a β-lactam side chain having active antibiotic properties;

R₂ is selected from the group consisting of H, OR_s, SR_e, and NHCOR₍, and where R₈ is a lower alkyl having 1-5 carbons, and R_e is selected from the group consisting of H and lower alkyls having 1-5 carbons;

X is selected from the group consisting of S, O, and CH₂;

R₃ is selected from the group consisting of H, lower alkyl having 1-5 carbons, aryl, halogen, OH, OR₅, SH, SR₆, NH₂, NHCOR_j and CH₂R₇;

SUBSTITUTE SHEET R₄ is selected from the group consisting of H, lower alkyl having 1-5 carbons, vinyl, substituted vinyl, aryl, halogen, OH, OR₅, SH, SR₅, NH₂, NHCOR_j, and CH₂R₇;

R₇ is selected from the group consisting of OCOR,, pyridinium, substituted pyridinium and aryl; and

R_β is selected from the group consisting of NH₂, H, and lower alkyls having from 1-5 carbons.

9. A method of claim 8, wherein the R_x group of the cephalosporin is -XQ, wherein X is O or S and Q is a lower alkyl having from 1-4 carbon atoms, a lower alkenyl having from 2-4 carbon atoms, or an aryl alkyl having from 1-4 carbon atoms.

10. A method of claim 9, wherein the R_x group of the cephalosporin is benzyl or phenoxyacetyl.

11. A method of claim 8, wherein the R_x group of the cephalosporin is -CH₂Y, wherein Y is H or a nucleophilic group.

SUBSTITUTE SHEET -28-

12. A method of therapy or prophylaxis of bacterial infection, comprising administering an antibacterial amount of a cephalosporin having the formula:

where R_λ is phenyl or substituted phenyl and M is H, Na+ or K+, R₂ is H or OCH, and R, is H or "CH,.

SUBSTITUTE SHEET