GB1568385A - (7-(a-(2-oxo-imidazolidin-1-yl-carbonylamino)-phenylacetamido-cephalosporins process for their preparation and their use as medicaments - Google Patents

Abstract

Novel cephalosporins of the formula <IMAGE> in which R1 represents methyl or methylsulphonyl and R2 represents 2-methyl-1,3,4-thiadiazol-5-yl or 1-methyl-1,2,3,4-tetrazol-5-yl and which, with respect to the centre of chirality C*, can be present in the two possible configurations R and S and as mixtures of the diastereomers resulting therefrom, and their non-toxic, pharmaceutically tolerable salts are prepared. These compounds are obtained by reacting an appropriate cephalosporin compound which has the acetoxymethyl radical in the 3-position with 2-methyl-5-mercapto-1,3,4-thiadiazole or 1-methyl-5-mercapto- 1,2,3,4-tetrazole in water or in solvents at a pH of 2-9 and at a temperature of 20-100 DEG C. Resulting cephalosporins are optionally converted into the free acids or into non-toxic, pharmaceutically tolerable salts. The novel cephalosporins are used as medicaments, in particular as antibacterial agents.

Description

(54) 7- t a -OXO-IMIDAZOLIDIN- 1-YL-CARBONYLAMINO) PHENYLACETAMIDO] -(2-CEPHALOSPORINS, PROCESSES FOR THEIR PREPARATION AND THEIR USE AS MEDICAMENTS (71) We, BAYER AKTIENGESELLSCHAFT, a body corporate organised under the laws of Germany, of Leverkusen, Bayerwerk, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement::- The present invention relates to new cephalosporins, processes for their preparation and their use as medicaments in human medicine and veterinary medicine, as therapeutic agents for poultry, mammals and fish, and as feedstuff additives and growth-promoting agents in animals, but especially to their oral and parenteral use as antibacterial agents in infectious diseases caused by Grampositive and Gram-negative bacteria.

It is known that certain acetamidocephalosporanic acids, for example cephaloglycin, which in the a-position of the acetamido group carry an aryl radical and an amino group, are accessible by synthesis and can be used as antibacterial agents. They are described in German Offenlegungsschriften (German Published Specifications) Nos. 1,670,625, 1,795,188 and 1,795,292, U.S. Patent Specifications Nos. 3,303,193, 3,352,858, 3,485,819 and 3,624,416, Japanese Application No.

16,871/66 and British Patent Specification No. 1,073,530. However, they are unable to combat infections caused, for example, by bacteria from the group of the Pseudomonads.

Further substituted acetamidocephalosporanic acids are described in DOS (German Published Specification) No. 2,428,139.

According to the present invention, we provide cephalosporins of the general formula I

wherein R1 represents methyl or methylsulphonyl and R2 represents 2-methyl-i ,3,4-thiadiazol-5-yl, and which can be in either one of the two possible configurations R (=D) and S with respect to the chirality centre C* or in the form of mixtures of the diastereomers resulting therefrom, and salts thereof.

Surprisingly, the compounds of the invention (i.e. the compounds of the formula I and their salts) exhibit a substantially greater antibacterial action, especially against bacteria from the families of the Enterobacteriaceae and Pseudomonadaceae than, for example, the cephalosporins Cephalexin and Cephalothin, known from the state of the art. Of the compounds of the invention which are salts therefore, those which are pharmaceutically acceptable are most important and preferred.

Further, it has been found that the compounds of the invention may be obtained by reacting compounds of the general formula II

wherein R, and C* have the abovementioned meaning, which compound may be used in the form of a salt or an easily split derivative of the acid carboxyl group, with 2 methyl-l ,3,4-thiadiazole-5-thiol, preferably in water, in aqueous solvents or in anhydrous solvents, at a pH of 2-9 and at a temperature of 20--100"C, and converting the resulting cephalosporins, if desired or appropriate, into the free acid or into salts.

If, for example, 7 - fD - a - [(2 - oxo - 3 - mesyl - imidazolidin - 1 - yl) - carbonylamino] - phenylacetamidol - 3 - acetoxymethyl - ceph - 3 - em - 4 - carboxylic acid and 2 - methyl - 1,3,4 - thiadiazole - 5 - thiol are used as starting materials, the course of the reaction can be represented by the following equation:

The following individual compounds are of the general formula I:: 7 - {D - a -[(2 - oxo - 3 - methyl - imidazolidin - 1 - yl) - carbonylamino]- phenylacetamidol - 3 - [(2 - methyl - 1,3,4 - thiadiazol - 5 - yl) - thiomethyl] - ceph3 - em - 4 - carboxylic acid

7 - ID - a - [(2 - oxo - 3 - mesyl - imidazolidin - 1 - yl) - carbonylamino] - phenylacetamidol - 3 - [(2 - methyl - 1,3,4 - thiadiazol - 5 - yl) - thiomethyl] - ceph - 3em - 4 - carboxylic acid

The preferred compound is 7 - (D - a- [(2 - oxo - 3 - methyl - imidazolidin - 1yl) - carbonylamino] - phenylacetamido} - 3 - [(2 - methyl - 1,3,4- thiadiazol - 5 - yl)thiomethyl] - ceph - 3 - em - 4 - carboxylic acid.

Preferred salts of the compounds of the formula I include the salts of the acid carboxyl group, for example sodium, potassium, magnesium, calcium, aluminium and ammonium salts, and non-toxic substituted ammonium salts with amines, such as dialkyl amines and trialkylamines (preferably C1-C4-alkyl), procaine, dibenzylamine, N,N'-dibenzylethylenediamine, N-benzyl-p-phenylethylamine. Nmethylmorpholine, N-ethylmorpholine, l-ephenamine, dehydroabietylamine, N,N'-bis-dehydro-abietylethylenediamine, N-C1-C7 alkylpiperidine and other amines usually employed in pharmaceutical chemistry, for example those which have also been used to form salts of penicillins.

The sodium salts of compounds of the formula I are particularly preferred.

All crystal forms, salts and hydrate forms of the compounds of the general formula I are equally suitable for use an antibacterial agents in the present invention. Thus, for example, the free acids and the sodium salts, both in an amorphous form and in a crystalline form, and both in the anhydrous form and in various hydrated forms, for example as the monohydrate, are suitable.

The preparation of the starting materials of the general formula II is described in the examples; they may be obtained as follows: Compounds of the formula IV

in which C* has the abovementioned meaning, or their salts, for example sodium salts, are reacted with approximately equimolar amounts of compounds of the formula V

in which R, has the abovementioned meaning and W represents halogen, especially chlorine, at temperatures between, preferably, 0 and 25"C, for example whilst cooling with ice/water. At the same time the pH value is maintained at from 7.0 to 7.5 by addition of a base for example triethylamine. The solvent used can be, for example, 20% (parts by volume) of aqueous tetrahydrofuran (THF). The mixture is stirred subsequently until no further triethylamine needs to be added in order to maintain this pH value.It is then diluted with water, the pH value is brought to 7.0 if necessary, the tetrahydrofuran is largely removed on a rotary evaporator, the solution which remains is washed once with ethyl acetate and is then covered with fresh ethyl acetate and acidified to pH 2.0 with dilute hydrochloric acid, whilst stirring and cooling, the organic phase is separated off, the aqueous phase is again extracted with ethyl acetate and the combined ethyl acetate extracts are then washed with saturated sodium chloride solution and dried over MgSO4. After removing the drying agent, the mixture is diluted with an equal volume of diethyl ether and the sodium salt of the compound of the formula II is then precipitated by adding an approximately 1 molar solution of sodium 2-ethylhexanoate in diethyl ether (which contains about 10% of methanol), and is filtered off and dried.

The compounds of the formula IV are already known or are obtainable in accordance with known methods (see for example, E.H. Flynn, Cephalosporins and Penicillins, Academic Press, New York and London, 1972).

The compounds of the formula V are known or are obtainable in accordance with know methods. They can be prepared, for example, in the usual manner by reacting the heterocyclic compounds of the general formula VI

in which R, has the abovementioned meaning, with, for example, molar amounts of phosgene, in inert organic solvents such as, for example, tetrahydrofuran, or in mixtures of water and inert organic solvents such as, for example, chloroform, at temperatures of 0 to 250C, in the absence or in the presence of the molar amount of a base, such as, for example, triethylamine, followed by customary working up and purification.

The compounds of the general formula II can be used in the form of all crystailine forms, hydrate forms, salts and easily split derivatives of the acid carboxyl group, such as, for example, the easily split esters, amides or hydrazides, as starting materials for the present invention.

2-Methyl-1,3,4-thiadiazole-5-thiol is itself known. Its preparation is described, for example, in J. prakt. Chem. 124, 275, (1930).

A suitable solvent for the reaction, according to the invention, of the compounds of the general formula II with 2-methyl-1,3,4-thiadiazole-5-thiol is above all water; however, mixtures of water with acetone, tetrahydrofuran, dioxane, acetonitrile, dimethylformamide, isopropanol, ethanol, dimethylsulphoxide and other water-miscible solvents, or the solvents listed here (individually or as mixtures), without added water, are also suitable for use as the reaction medium.

The pH value of the reaction according to the invention can be varied within wide limits by adding acids or bases or buffer mixtures, for example between 2 and 9, a pH value of 5 being preferred.

The reaction temperatures can also be varied within a substantial range. In general, the reaction is carried out between +20 and 100"C, preferably between 50 and 80"C.

As with most chemical reactions, higher or lower temperatures than those mentioned in the examples can be used. If, however, the values mentioned there are exceeded substantially, side-reactions will occur increasingly, which reduce the yield or adversely influence the purity of the products. On the other hand, excessively lowered reaction temperatures so greatly reduce the rate of reaction that the yields can fall.

The reaction can be carried out under normal pressure, but also under reduced pressure or elevated pressure. In general, it is carried out under normal pressure.

In carrying out the process according to the invention the reactants can be reacted with one another in equimolecular amounts. However, it is frequently advantageous to employ the 2-methyl-l,3,4-thiadiazole-5-thiol in an excess of 0.5-2.5 moles, in order to achieve complete reaction with reactants of the general formula II.

The working up of the reaction batch in order to prepare the cephalosporins according to the invention, and their salts, is in every case carried out in the manner generally know from cephalosporin chemistry.

Further, it has been found that the new compounds of the general formula I are also obtained when compounds of the general formula III

wherein R2 and C* have the abovementioned meaning, are reacted with compounds of the general formula V

wherein R, and W have the abovementioned meaning, in anhydrous or aqueous solvents or in water, in the presence of a base, at a temperature of -20 to +50 C, and the cephalosporins thereby obtained are converted, if desired, into their salts.

Further, it has been found that the new compounds of the general formula I are also obtained when compounds of the general formula VII

wherein R2 has the abovementioned meaning are reacted with compounds of the general formula VIII

wherein R1 and C* have the abovementioned meaning, and which are activated beforehand, at the carboxyl group, in the manner generally known from peptide, penicillin and cephalosporin chemistry. The activation can be effected, for example, by conversion to an activated ester, for example with pnitrophenol or N-hydroxysuccinimide, or by conversion to a mixed anhydride, for example by reaction with chloroformic acid esters, pivaloyl chloride, dimethylchloroformimidium chloride or tetramethylchloroformamidinium chloride, or by reaction with a carbodiimide such as dicyclohexylcarboxiimide.

However, the activation can also be effected, for example, by converting the carboxylic acids of the general formula VIII into the acid halides or azides.

The compounds according to the invention couple a low toxicity with a strong antibacterial activity. These properties permit their use as chemotherapeutic active compounds in medicine and as materials for preserving inorganic and organic materials, especially organic materials of all kinds, for example polymers, lubricants, dyestuffs, fibres, leather, paper and timber, as well as foodstuffs and water.

The active compounds according to the invention are active against a very broad spectrum of micro-organisms. They can be used, for example, to combat Gram-negative and Gram-positive bacteria and bacteria-like micro-organisms and to prevent, ameliorate and/or heal illnesses caused by these pathogens.

The active compounds according to the invention are particularly active against bacteria and bacteria-like micro-organisms. They are therefore particularly suitable for the prophylaxis and chemotherapy of local and systemic infections, caused by these pathogens, in human medicine and veterinary medicine.

For example, local and/or systemic illnesses caused by the following pathogens or by mixtures of the following pathogens can be treated and/or prevented: Micrococcaceae, such as Staphylococci, for example Staphylococcus aureus, Staph. epidermidis, Staph. aerogenes and Gafjkya tetragena (Staph.

Staphylococcus); Lactobacteriaceae, such as Streptococci, for example Streptococcus pyogenes.

a- or p-haemolytic Streptococci, non-(y)-haemolytic Streptococci, Str, viridans, Str. faecalis (Enterococci), Str. agalactiae, Str. lactis, Str. equi, Str. anaerobis and' Diplococcus pneumoniae (Pneumococci) (Str. = Streptococcus); Neisseriaceae, such as Neisseriae, for example Neisseria gonorrhoeae (Gonococci), N. men in gitidis (Meningococci), N. catarrhalis and N. flava (N. = Neisseria); Corynebacteriaceae, such as Corynebacteria, for example Corynebacterium diphtheriae, C. pyogenes, C. dtphtheroides. C. acnes, C. parvum, C. bovis, C. renale, C.

ovis and C. murisepticum, (C. = Corynebacterium); Enterobacteriaceae, such as Escherichiae bacteria of the Coil group, Escherichia bacteria, for example Escherichia coli, Enterobacter bacteria, for example E. aerogenes and E. cloacae, Klebsiella bacteria, for example K.

pneumoniae and K. ozaenae, Erwiniae, for example Er win ia spec., Serratia, for example Serratia marcescens (E. = Enterobacter) (K. = Kelbsiella), Proteae bacteria of the Proteus group, Proteus, for example Proteus vulgaris. Pr. morganii, Pr. rettgeri and Pr. mirabilis (Pr. = Proteus), Providencia, for example Providencia sp., Salmonelleae, Salmonella bacteria, for example Salmonella paratyphi A and B, S.

typhi. S. enteritidis, S. cholerae suis and S. typhimurium (S. = Salmonella), and Shigella bacteria, for example Shigella dysenteriae, Sh. ambigua, Sh. flexneri, Sh.

boydii and Sh. sonnei (Sh. = Shigella); Pseudomonadaceae, such as Pseudomonas bacteria, for example Pseudomonas aeruginosa and Ps. pseudomallei (Ps. = Pseudomonas), and Aeromonas bacteria, for example Aeromonas liquefaciens and A. hydrophila (A. = Aeromonas); Spirillaceae, such as Vibrio bacteria, for example Vibrio cholerae, Parvobacteriaceae or Brucellaceae, such as Pasteurella bacteria, for example Pasteurella multocida, Past. pestis (Yersinia), Past. pseudo tuberculosis and Past.

tularensis (Past. = Pasteurella), Brucella bacteria, for example Brucella abortus, Br.

melitensis and Br. suis (Br. = Brucella), Haemophilus bacteria, for example Haemophilus influenzae, H. ducreyi, H. suit, H. can is and H. aegypitcus (H. = Haemophilus) Bacteroidacea, such as Bacteroides bacteria, for example Bacteroides fragilis and B. serpens (B. = Bacteroides); Bacillaceae, such as aerobic spore-forming organisms, for example Bacillus anthrancis. B. subtilis and B. cereus (B. = Bacillus) and anaerobic spore-forming organisms -- Clostridia, for example Clostridium perfringens, Cl. septicium, Cl.

oedematiens, Cl. histolvticum, Cl. tetani and Cl. botulinum (Cl. = Clostridium); The above list of pathogens is purely illustrative and is in no way to be interpreted as restrictive.

The following may be mentioned as examples of illnesses which can be prevented, ameliorated and/or healed by the active compounds according to the invention: Illnesses of the respiratory passages and of the pharyngeal cavity; otitis; pharyngitis; pneumonia; peritonitis; pyelonephritis; cystitis; endocarditis; systemic infections; bronchitis; and arthritis.

The present invention provides a pharmaceutical composition containing as active ingredient a compound of the invention in admixture with a solid or liquefied gaseous diluent or in admixture with a liquid diluent other than a solvent of a molecular weight less than 200 (preferably less than 350) except in the presence of a surface active agent.

The invention further provides a pharmaceutical composition containing as active ingredient a compound of the invention in the form of a sterile or isotonic aqueous solution.

The invention also provides a medicament in dosage unit form comprising a compound of the invention either alone or in admixture with a diluent.

The invention also provides a medicament in the form of tablets (including lozenges and granules), dragees, capsules, pills, ampoules or suppositories comprising a compound of the invention either alone or in admixture with the diluent.

"Medicament" as used in this Specification means physically discrete coherent portions suitable for medical adminstration. "Medicament in dosage unit form" as used in this Specification means physically discrete coherent units suitable for medical administration each containing a daily dose or a multiple (e.g.

up to four times) or sub-multiple (e.g. down to a quarter) of a daily dose of the compound of the invention in association with a carrier and/or enclosed within an envelope. Whether the medicament contains a daily dose or, for example, a half, a third, or a quarter of a daily dose will depend on whether the medicament is to be administered once or, for example, twice, three times or four times a day respectively.

The pharmaceutical compositions according to the invention may, for example, take the form of ointments, gels, pastes, creams, sprays (including aerosols), lotions, suspensions, solutions and emulsions of the active ingredient in aqueous or non-aqueous diluents, syrups, granules or powders.

The diluents to be used in pharmaceutical compositions (e.g. granulates) adapted to be formed into tablets, rages, capsules and pills include the following: (a) fillers and extenders, e.g. starch, sugars, mannitol, and silicic acid; (b) binding agents, e.g. carboxymethyl cellulose and other cellulose derivatives, alginates, gelatine and polyvinyl pyrrolidone; (c) moisturizing agents, e.g. glycerol; (d) disintegrating agents, e.g. agar-agar, calcium carbonate and sodium bicarbonate; (e) agents for retarding dissolution e.g. paraffin; (f) resorption accelerators, e.g.

quaternary ammonium compounds; (g) surface active agents, e.g. cetyl alcohol, glycerol monostearate; (h) adsorptive carriers, e.g. kaolin and bentonite; (i) lubricants, e.g. talc, calcium and magnesium stearate and solid polyethylene glycols.

The tablets, dragees, capsules and pills formed from the pharmaceutical compositions of the invention can have the customary coatings, envelopes and protective matrices, which may contain opacifiers. They can be so constituted that they release the active ingredient only or preferably in a particular part of the intestinal tract, possibly over a period of time. The coatings, envelopes and protective matrices may be made, for example, of polymeric substances or waxes.

The ingredient can also be made u in microencapsulated form together with one or several of the above-mentioned diluents.

The diluents to be used in pharmaceutical compositions adapted to be formed into suppositories can, for example, be the usual water-soluble or water-insoluble diluents, such as polyethylene glycols and fats (e.g. cocoa oil and high esters [e.g.

C,4-alcohol with C16-fatty acid]) or mixtures of these diluents.

The pharmaceutical compositions which are ointments, pastes, creams and gels can, for example, contain the usual diluents, e.g. animal and vegetable fats, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc and zinc oxide or mixtures of these substances.

The pharmaceutical compositions which are powders and sprays can, for example, contain the usual diluents, e.g. lactose, talc, silicic acid, aluminium hydroxide, calcium silicate, and polyamide powder or mixtures of these substances.

Aerosol sprays can, for example, contain the usual propellants, e.g.

chlorofluorohydrocarbons.

The pharmaceutical compositions which are solutions and emulsions can, for example, contain the customary diluents (with, of course, the above-mentioned exclusion of solvents having a molecular weight below 200 except in the presence of a surface-active agent), such as solvents, dissolving agents and emulsifiers; specific examples of such diluents are water, ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzylbenzoate, propylene glycol, 1,3butylene glycol, dimethylformamide, oils (for example ground nut oil), glycerol, tetrahydrofurfuryl alcohol, polyethylene glycols and fatty acid esters of sorbitol or mixtures thereof.

For parenteral adminstration, the solutions and emulsions should be sterile, and, if appropriate, blood-isotonic.

The pharmaceutical compositions which are suspensions can contain the usual diluents, such as liquid diluents, e.g. water, ethyl alcohol, propylene glycol, surfaceactive agents (e.g. ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters), microcrystalline cellulose, aluminium metahydroxide, bentonite, agar-agar and tragacanth or mixtures thereof.

All the pharmaceutical compositions according to the invention can also contain colouring agents and preservatives as well as perfumes and flavouring additions (e.g. peppermint oil and eucalyptus oil) and sweetening agents (e.g.

saccharin).

The pharmaceutical compositions according to the invention generally contain from 0.1 to 99.5, more usually from 0.5 to 95 % of the active ingredient by weight of the total composition.

In addition to a compound of the invention, the pharmaceutical compositions and medicaments according to the invention can also contain other pharmaceutically active compounds. They may also contain a plurality of compounds of the invention.

Any diluent in the medicaments of the present invention may be any of those mentioned above in relation to the pharmaceutical compositions of the present invention. Such medicaments may include solvents of molecular weight less than 200 as sole diluent.

The discrete coherent portions constituting the medicament according to the invention will generally be adapted, by virtue of their shape or packaging, for medical administration and may be, for example, any of the following: tablets, (including lozenges and granules), pills, dragees, capsules, suppositories and ampoules. Some of these forms may be made up for delayed release of the active ingredient. Some, such as capsules, include a protective envelope which renders the portions of the medicament physically discrete and coherent.

The preferred daily dose for administration of the medicaments of the invention is 0.1 g to 80 g of active ingredient.

The production of the above-mentioned pharmaceutical compositions and medicaments is carried out by any method known in the art, for example, by mixing the active ingredient(s) with the diluent(s) to form a pharmaceutical composition (e.g. a granulate) and then forming the composition into the medicament (e.g.

tablets).

This invention further provides a method of combating (including prevention, reliet and cure of) the above-mentioned diseases in non-human animals, which comprises administering to the animals a compound of the invention alone or in admixture with a diluent or in the form of a medicament according to the invention.

It is envisaged that these active compounds will be administered perorally, parenterally (for example intramuscularly, intraperitoneally or intravenously), rectally or locally, preferably parenterally, especially intravenously or intramuscularly. Preferred pharmaceutical compositions and medicaments are therefore those adapted for parenteral administration.

In general it has proved advantageous both in human medicine and in veterinary medicine to administer the active compound or compounds according to the invention in total amounts of 6 to 800, preferably 15 to 300, mg/kg of body weight every 24 hours, optionally in the form of several, for example 3, individual doses, in order to achieve the desired results. An individual dose contains the active compound or the active compounds according to the invention preferably in amounts of 2 to 300, especially of 5 to 100, mg/kg of body weight. However, it can be necessary to deviate from the dosages mentioned and in particular to do so as a function of the nature and body weight of the subject to be treated, the nature and the severity of the illness, the nature of the preparation and of the administration of the medicine, and the time or interval over which the administration takes place.

Thus it can suffice in some cases to manage with less than the abovementioned amount of active compound whilst in other cases the abovementioned amount of ve compound must be exceeded. The particular required optimum dosage and the type of administration of the active compounds can easily be decided by anyone skilled in the art, on the basis of his expert knowledge.

The invention also includes medicated fodder comprising a compound of the invention in admixture with a nutritious material such as oil cake, grain (e.g.

barley), fish meal, soya bean meal, exhausted sugar beet chips, silage, hay and skimmed milk.

Where used as a feedstuff additive, the compounds of the invention can be administered in the usual manner together with the feedstuff or with feedstuff preparations or with the drinking water. By this means, an infection by Gramnegative or Gram-positive bacteria can be prevented and, equally, better utilisation of the feedstuff can be achieved.

The new cephalosporins are distinguished by strong antibacterial effects, which have been tested in vivo and in vitro, and by oral resorbability.

The cephalosporins according to the invention can be combined with aminoglycoside antibiotics such as Gentamicin, Kanamicin, Sisomicin, Amikacin or Tobramicin, for the purpose of broadening the spectrum of action or boosting the action.

The activity of the cephalosporins according to the invention can be demonstrated, by way of example, by the following in vitro and in vivo experiments: a) In vitro experiment The cephalosporin of the specific Example, which can be regarded as typical of the compounds according to the invention, was diluted with Muller-Hinton nutrient broth, with addition of 0.1% by weight of glucose, to a strength of 100 jg/ml.

The nutrient solution in each case contained 1 x 105 to 2 x 105 bacteria per millilitre. The test tubes containing this charge were each incubated for 24 hours and the degree of turbidity was then determined. Freedom from turbidity indicates action.At a dosage of 100 ,ug/ml the following bacterial cultures were free from turbidity (sp. = species): Kiebsiella pneumoniae; Enterobacter aerogenes sp.; Providencia; Serratia marcescens: Escherichia coli BE; Salmonella sp.; Shigella sp. Proteus, indole negative and indole-positive sp.; Pasteurella pseudotuberculosis; Brucella sp.; Haemophilus influenzae; Bordetella bronchiseptica; Staphylococcus aureus 133; Neisseria catarrhalis sp.; Diplococcus pneumoniae sp.; Streptococcus pyogenes W; Enterococcus sp.; Lactobacillus sp.; Corynebacterium diphteriae gravis; Corynebacterium pyogenes M; Clostridium botulinum; Clostridium tetani.

b) In vivo experiment Table I shows the dosages employed for one of the cephalosporins according to the invention, which can be regarded as typical of the compounds according to the invention, against a series of bacteria in animal experiments with white mice.

The white mice, of strain CF1, where infected intraperitoneally with the particular species of bacteria indicated.

Table 1.

Animal experiments with white mice Determination of the ED60 after 24 hours

Dose in mg of the cephalosporin from Example 1 and 2 per kg of body weight Germ (subcutaneously administered) E coli Neumann 1 x 200 Example 1 Ps. aenig. W. 4 x 150 Es coli Neumann 1 x 100 Kleb, ella 63 2 x 50 Therapy: 1 administration: 30 minutes after infection 2 administrations: 30 minutes and 90 minutes after infection 4 administrations: 30 minutes after infection and 2, 4 and 6 hours after infection.

The ED50 is the dose at which 50% of the infected animals still survive after 24 hours.

The preparation of the compounds according to the invention, of the formula I, will be illustrated with the aid of the Example which follows: Explanation of abbreviations used: pts. by wt. = parts by weight in grams pts. by vol. = parts by volume in millilitres min. = minutes hr. = hour hrs. = hours m.p. = melting point dec.p. = decomposition point i.v. = in vacuo ether = diethyl ether DMSO = dimethylsulphoxide mesyl = methylsulphonyl All the yields quoted in % relate to % of theory.

All temperatures are given in "C.

Example.

This cephalosporin was prepared from sodium 7 - iD - a - [(2 - oxo - 3 - mesylimidazolidin - 1 - yl) - carbonylaminol - phenylacetamidol - 3 - acetoxymethylceph - 3 - em - 4 - carboxylate and 2 - methyl - 1,3,4 - thiadiazole - 5 - thiolj as follows: a mixture of 1.23 pts. by wt. of sodium 7 - iD - a - [(2 - oxo - 3 - mesyl - imidazolidin I - yl) - carbonylamino] - phenylacetamidol 3 - acetoxymethyl - ceph - 3 - em - 4- carboxylate, 0.66 pt. by wt. of 2 - methyl - 1,3,4 - thiadiazole - 5 - thiol and 20 pts. by vol. of I molar phosphate buffer (pH = 7) was heated at pH = 5 under a nitrogen atmosphere for 5 hrs. at 700 C, then cooled to room temperature, adjusted to pH = 7 extracted once with 20 pts. by vol. of ethyl acetate, which was discarded, then covered with 150 pts. by vol. of ethyl acetate and subsequently brought to pH = 2.

The precipitate of the cephalosporin acid which was present was filtered off and rinsed with 50 pts. by vol. of ethyl acetate. The acid was dissolved in a little dimethylacetamide, and 0.5 pt. by vol. of a 1 molar solution of sodium 2-ethylhexanoate in ether containing methanol was added, after which ether was added.

until the sodium salt of the cephalosporin had been precipitated completely.

The ethyl acetate phase obtained above was separated off and washed once with 50 pts. by vol. of water and dried over MgSO4, and 2.5 pts by vol. of a I molar solution of sodium 2-ethylhexanoate in ether containing methanol were added. The mixture was evaporated on a rotary evaporator until an oily consistency was reached, and was dissolved in a two-fold amount by volume of methanol, and added dropwise, with vigorous stirring, to ice-cold ether containing 10% of methanol. The product was filtered off, washed with ether and dried over P2Os in a desiccator.

Total yield of 1st + 2nd fraction of sodium 7 - iD - a - [(2 - oxo - 3 - mesylimidazolidin - I - yl) - carbonylamino] - phenylacetamido} - 3 - [(2 - methyl - 1,3,4- thiadiazol - 5 - yl) - thiomethyl] - ceph - 3 - em - 4 - carboxylate; 64%. p-lactam content according to the IR and NMR spectrum: 85%. IR bands at 3,350, 3,270, 1,780, 1,745, 1,655, 1,595, 1,520, 1,342 and 1,155 cm~l (in Nujol -- Registered Trade Mark).

NMR signals at = 0.7 (ism); 1.15 (lem); 2.3-3.0 (5H); 4.1--4.6 (2H); 5.1 (lem); 5.5 (2H); 6.1 (4H); 6.6 (3H); 6.3--6.9 (2H) and 7.43 ppm (3H) (in DMFHi7).

Sodium 7 - ID - a - [(2 - oxo - 3 - mesyl - imidazolidin - 1 - yl) - carbonylamino]- phenylacetamido) - 3 - acetoxymethyl - ceph - 3 - em - 4 - carboxylate was prepared in 71% yield, in the following manner: 1.3 pts. by wt. of cephalosporin dihydrate were dissolved in 30 pts. by vol. of 80% strength aqueous tetrahydrofuran by means of the exact amount of triethylamine necessary. 0.77 pt. by wt. of l-chlorocarbonyl-2- oxo-3-mesyl-imidazolidine was then introduced at 20"C, whilst stirring. In the course thereof, and subsequently, the pH was kept at 7.0 by appropriate addition of triethylamine. The mixture was stirred further until it was no longer necessary to add triethylamine to maintain a pH of 7.0 (about I hr.).It was then diluted with an equal volume of water, the pH was adjusted to 6.5, the tetrahydrofuran was removed in vacuo, the aqueous solution which remained was covered with a mixture of ether and ethyl acetate (1:1) and acidified to pH 2 whilst stirring, and cooling gently, the organic phase was separated off, washed with water and dried over magnesium sulphate, and the sodium salt of the cephalosporin was.

precipitated by means of an approximately 1 molar sodium 2-ethylhexanoate solution in ether containing methanol. The sodium salt separated out as a precipitate which was gel-like but filtrable. After washing with ether, it was dried in a desiccator.

WHAT WE CLAIM IS: 1. A cephalosporin of the formula I

wherein R1 represents methyl or methylsulphonyl and R represents 2-methyl-1,3,4-thiadiazol-5-yl and which is in either one of the two possible configurations R (=D) and S with respect to the chirality centre C* or in the form of a mixture of the diastereomers resulting therefrom, or a salt thereof.

2. 7 - ID - a - [(2 - Oxo - 3 - methyl - imidazolidin - 1 - yl) - carbonylamino] phenylacetamidol - 3 - [(2 - methyl - 1,3,4 - thiadiazol - 5 - yl) - thiomethyl] - ceph.

3 - em - 4 - carboxylic acid of the formula

or a salt thereof.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (19)

**WARNING** start of CLMS field may overlap end of DESC **. thiadiazol - 5 - yl) - thiomethyl] - ceph - 3 - em - 4 - carboxylate; 64%. p-lactam content according to the IR and NMR spectrum: 85%. IR bands at 3,350, 3,270, 1,780, 1,745, 1,655, 1,595, 1,520, 1,342 and 1,155 cm~l (in Nujol -- Registered Trade Mark). NMR signals at = 0.7 (ism); 1.15 (lem); 2.3-3.0 (5H); 4.1--4.6 (2H); 5.1 (lem); 5.5 (2H); 6.1 (4H); 6.6 (3H); 6.3--6.9 (2H) and 7.43 ppm (3H) (in DMFHi7). Sodium 7 - ID - a - [(2 - oxo - 3 - mesyl - imidazolidin - 1 - yl) - carbonylamino]- phenylacetamido) - 3 - acetoxymethyl - ceph - 3 - em - 4 - carboxylate was prepared in 71% yield, in the following manner: 1.3 pts. by wt. of cephalosporin dihydrate were dissolved in 30 pts. by vol. of 80% strength aqueous tetrahydrofuran by means of the exact amount of triethylamine necessary. 0.77 pt. by wt. of l-chlorocarbonyl-2- oxo-3-mesyl-imidazolidine was then introduced at 20"C, whilst stirring. In the course thereof, and subsequently, the pH was kept at 7.0 by appropriate addition of triethylamine. The mixture was stirred further until it was no longer necessary to add triethylamine to maintain a pH of 7.0 (about I hr.).It was then diluted with an equal volume of water, the pH was adjusted to 6.5, the tetrahydrofuran was removed in vacuo, the aqueous solution which remained was covered with a mixture of ether and ethyl acetate (1:1) and acidified to pH 2 whilst stirring, and cooling gently, the organic phase was separated off, washed with water and dried over magnesium sulphate, and the sodium salt of the cephalosporin was. precipitated by means of an approximately 1 molar sodium 2-ethylhexanoate solution in ether containing methanol. The sodium salt separated out as a precipitate which was gel-like but filtrable. After washing with ether, it was dried in a desiccator. WHAT WE CLAIM IS:

1. A cephalosporin of the formula I

wherein R1 represents methyl or methylsulphonyl and R represents 2-methyl-1,3,4-thiadiazol-5-yl and which is in either one of the two possible configurations R (=D) and S with respect to the chirality centre C* or in the form of a mixture of the diastereomers resulting therefrom, or a salt thereof.

2. 7 - ID - a - [(2 - Oxo - 3 - methyl - imidazolidin - 1 - yl) - carbonylamino] phenylacetamidol - 3 - [(2 - methyl - 1,3,4 - thiadiazol - 5 - yl) - thiomethyl] - ceph.

3 - em - 4 - carboxylic acid of the formula

or a salt thereof.

3. 7 - {D - a - [(2 - Oxo - 3 - mesyl - imidazolidin - I - yl) - carbonylamino]

phenylacetamido} - 3 - [(2 - methyl - 1,3,4 - thiadiazol - 5 - yl) - thiomethyl] - ceph3 - em - 4 - carboxylic acid of the formula

or a salt thereof.

4. A compound according to any one of claims I to 3 in the form of a sodium salt.

5. A process for the preparation of a compound according to any one of claims 1 to 4, which comprises reacting a compound of the formula II

wherein R, and C* are as defined in any one of claims 1 to 4 which compound is optionally in the form of a salt or an easily split derivative of the acid carbonyl group, with 2-methyl- 1,3,4-thiadiazole-5-thiol and, if desired, converting the resulting cephalosporin into a salt where the free acid compound of formula II is employed, or, if desired or necessary, converting the resulting cephalosporin into the free acid where a salt or derivative of the compound of formula II is employed.

6. A process according to claim 5 wherein the reaction is conducted in water, an aqueous solvent or in an anhydrous solvent at a pH of from 2 to 9 and at a temperature of from 20 to 1000C.

7. A process for the preparation of a compound according to any one of claims I to 4, which comprises reacting a compound of the formula III

wherein R2 and C* are as defined in any one of claims 1 to 4, with a compound of the general formula V

wherein R1 is as defined in any one of claims 1 to 4 and W represents halogen, in anhydrous or aqueous solvents or in water in the presence of a base, and converting the resulting compound, if desired, into a salt.

8. A process for the preparation of a compound according to any one of claims 1 to 4 which comprises reacting a compound of the formula VII

wherein R2 is as defined in any one of claims 1 to 4, with a compound of the general formula VIII

wherein R, and C* is as defined in any one of claims I to 4, which is activated beforehand at the carboxyl group, and converting the resulting compound, if desired, into a salt.

9. A process for the preparation of a compound according to claim 1 substantially as hereinbefore described in the specific Example.

10. A compound according to claim 1 whenever prepared by a process according to any one of claims 5 to 9.

11. A pharmaceutical composition containing as an active ingredient a compound according to any one of claims 1 to 4 and 10 in admixture with a solid or liquefied gaseous diluent or in admixture with a liquid diluent other than a solvent of a molecular weight less than 200 except in the presence of a surface-active agent.

12. A pharmaceutical composition containing as an active ingredient a compound according to any one of claims 1 to 4 and 10 in the form of a sterile or isotonic aqueous solution.

13. A composition according to claim 11 or 12 containing from 0.5 to 95% by weight of the said active ingredient.

14. A medicament in dosage unit form comprising a compound according to any one of claims 1 to 4 and 10.

15. A medicament in the form of tablets, pills, dragees, capsules, ampoules, or suppositories comprising a compound according to any one of claims 1 to 4 and 10.

16. A method of combating bacterial infection in non-human animals which comprises administering to the animals an active compound according to any one of claims I to 4 and 10 either alone or in admixture with a diluent or in the form of a medicament according to claim 14 or 15.

17. A method according to claim 16 in which the active compound is administered in an amount of 6 to 800 mg per kg body weight per day.

18. A method according to claim 16 or claim 17 in which the active compound is administered parenterally.

19. Medicated fodder comprising a compound according to any one of claims I to 4 and 10 in admixture with a nutritious material.