IE45686B1 - 7-acylamino-3-(sulfomethylheterocyclicthiomethyl)-3-cephem-4-carboxylic acids - Google Patents

Abstract

Novel 7-acylamino-3-(sulphomethylthiadiazolylthiomethyl)- or -(sulphomethyltriazolylthiomethyl)-3-cephem-4-carboxylic acids exhibit antibacterial activity against gram-positive and gram-negative bacteria. They are prepared by reacting a corresponding 7-amino- or 7-acylamino-3-acetoxymethyl-cephalosporanic acid with a corresponding sulphomethylthiadiazole-thiol or sulphomethyltriazole-thiol. If a 7-amino-3-acetoxymethyl-cephalosporanic acid is employed, the product is subsequently N-acylated.

Description

This invention, relates to certain cephalosporin .derivatives processes for their preparation and pharmaceutical compositions containing them.

Accordingly the present invention provides compounds of formula (I) :- where Ac is a pharmaceutically acceptable acyl group as defined herein, R1 is hydrogen or methoxy.

E is -S- or -NH- and pharmaceutically acceptable salts and esters thereof.

By a pharmaceutically acceptable acyl group in this specification is meant an acyl group known to be of use as a substituent at the 7-position in known antibacterially active cephalosporins or in the 6-position of known antibacterially active penicillins with the proviso that Ac does not contain a substituted or unsubstituted thiazole or thiazoline group.

Examples of acyl substituents Ac are : 0 0 a H ii X-CH-C-, Y-CH2-C- or a-S(O)m-GH2-C“ A wherein : X is thienyl, furyl, phenyl or phenyl monosubstituted - 2 4 5 6 8 6 with hydroxy, hydroxymethyl, formamido or ureido; A is NH2, OH, COOH, SO3H, formyloxy or, methoxyimino (α-C-hydrogen then being absent); Y is cyano, sydnonyl, pyridonyl, thienyl, aminornethylphenyl, phenyl or tetrazolyl; Z is methyl, trifluoromethyl, trifluoroethyl, pyridyl or cyanomethyl; and m is zero, one or two.

Each of the three partial structures above represents a subgeneric group of compounds within this invention.

Examples of 7-acylamino substituents which AcNH represents are : u-hydrexyphenylacetamido ix-aminophcnylacetamido a-araino-4-hydroxyphenylacetamido trifluoromethylthioacetamido 2,2,2-trifluoroethylsulfinylacetamido 2,2,2-tri fluoroethylthioacetamido cyanoacetamido a-carboxy-a-thienylacetamido a-carboxyphenylacetamido u-sulfophenvlacetamido methylsulfonylacetamido cyanomethylthioacetamido 3- sydnonylacetamido ( l-tetrazolylaeetamido 2-thienylacatamido syn-2-methoxyimino-2-a-furylacefcamido 4- pyridylthioacetamido and o-amin ome thylphenylacetamido Others may be found in Cephalosporins and Penicillins, Flynn, Academic Press, 1972. 45®s® It will of course be appreciated that free functional groups in the acylamino substituent at position-7 in compounds, of formula (I) can be converted into various derivatives particularly pharmaceutically acceptable derivatives. For example hydroxy and carboxyl groups (e.g. where A is -COOH) can be converted into esters.

Carboxyl groups can also be converted into salts.

Examples of carboxyl group esters and salts are as discussed below with reference to esters and salts of the cephem-4-carboxylic acid group. Amino groups in a 710 glycylamino group can be converted into an amide derivative for example a furyl-, pyranyl-, oxolanyl- or oxiranylcarbonylamides. It will be understood that derivatives of this type will fall within the term pharmaceutically acceptable acylamino groups.

It will be recognized that the 4-carboxylic acid group of the compounds of formula (I) forms esters and salts. Examples of these esters include simple alkyl and aryl esters, and esters which are easily cleaved within the body, to fhe parent acid in particular indanyl, pivaloyloxymethyl,· acetoxymethyl, propionyloxymethyl, glycyloxymethyl, phenylglycyloxymethyl and thienylglycyloxy methyl esters. When A is COOH, this group may be similarly esterified.

Examples of particular compounds of formula (I) are :7-0-(-)Mandelamidof3-(3-sulfomethyl-1,2,4-triazol-530 thiomethyl)-3-cephem-4-oarboxylic acid 7- □-(-) Madelamido -3-(5-sulfomethyl~l,3,4-thiadiazol-2ylthiomethyl)-3-cephem-4-carboxylic acid - 4 4 5 6 3 0 7~(D-a-Amino-4--hydroxyphenylacetamido) -3-(3-sulfomethyl1,2,4~triazol-5-thiomethyl)-3-cephem-4-carboxylic acid, 7-DL- (a-Aininophenylacetamido)-3- (3-sulfomethyl-l, 2,4-triazole-5-ylthiomethyl)-3-cephem-4-carboxylie acid, 7_Trifluoromethylthioacetamido-3-(3-sulfomethyl-l,2,4triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid, 7-(2-Thienylacetamido)-3-(3-sulfomethyl-l,2,4-triazol-5~ ylthiomethyl)-3-cephem-4-carboxylic acid 7-D~fe~?.mino-4-hydroxyphenylacetamido) -3- (5-sulfomethyl1,3,4-thiadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 7-DX,- ( σ-Arainophenylacetamido) -3- (5-sulfomethyl-l ,3,4thiadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid 7'rflri£luorGinethylthioacetainidO”3- (5-sulfomethyl-l, 3,4thiadis3Ol-2-ylthiomethyl-3-cephem-4-carboxylic acid and 7-(2-Thienylacetamido)-3-(5-sulfomethyl-l,3,4-thiadiasol2-ylthiomethyl)-3-cephem-4~carboxylic acid.

Examples of salts of compounds of formula (I) include pharmaceutically acceptable salts in particular, alkali metal salts especially the sodium and potassium salts, ammonium salts and organic amine salts for example those with procaine or dibenzylethylenediamine. ·' cl· Some compounds of the invention have an asymmetric group Ac for example a mandelamido or phony! glycyl ami do group. The D-foxrms of these compounds are preferred. ?5 Compounds of formula (Ϊ) and their salts and esters can exist in the form of solvates for example hydrates and 86 alcoholates. It is appreciated that such forms are within the scope of this invention.

The compounds of the invention can be prepared by , .from displacement of acetoxy/a 7-acylamino cephalosporanic acid derivative.

Accordingly the invention also provides a process for preparing a compound of formula (I) above or a salt or ester thereof which comprises reacting a compound of formula (II) :R' ,1 co2h (II) er a salt or ester thereof where R1 and Ac are as defined with reference to formula (I) and in which any carboxy, sulfo, amino, or hydroxy groups are optionally protected; with a thiol of formula (III) :NHS •E' (III) where E is as defined with reference to formula (I) and the sulfo group is optionally protected, or a salt thereof, optionally convertinc the group R^ when it is hydrogen into Methoxy by a known Method, reMoving any protecting groups and optionally 4E6S6 converting the product so obtained into a salt or ester.

Examples of thiols of formula (III) are :3-sulfomethyl-l,2,4-triazol -5--thiol and 5 5-sulfomethyl-l,3,4-thiadiazol -2-thiol Compounds of formula (II) are known or can be made by analogy with known processes from 7-amino cephalosporanic acid.

The compounds of the invention can also be prepared by acylating a corresponding 7-amino cephalosporanic acid derivative. Accordingly the invention further provides a process for preparing a compound of formula (I) above or a salt or ester thereof which comprises reacting a compound of formula (IV) :- (IV) where £ and are as defined vzith reference to formula (1) and in which any carboxyl and sulfo groups are optionally protected with an acylating agent capable of supplying the 3,, acyl moiety Ac in which any carboxyl, amino, sulfo, or hydroxy groups are optionally protected thereafter optionally converting the group R·*· when it is hydrogen into methoxy by a known method., removing any protecting groups and optionally converting the product so obtained into a salt or ester.

The acylation step can be carried out by .analogy - 7 I with known processes for acylating the 7-amino substituent of 7-aminocephalosporanic acid derivatives.

By a known method in either of the above processes is meant a method in actual use or described in the literature.

When is methoxy, preferably the group is introduced prior to the acylation step.

Protecting groups which may be used in either process are known in the art (see Protective Groups in Organic Chemistry, J.F. W. McOmie, Plenum Press, 1973, Chapters 2 and 3 for use of amino, carboxy, sulfo or hydroxyl protective groups). Examples are t-butyl for COOH and t-butoxycarbonyl for NHn. These groups can be removed easily by treatmsnt with trifluoroacetifc acid.

Esters of compounds of formula (I) can be prepared by known methods.

Salts of compounds of formula (I) can be prepared by known methods, for example sodium and potassium salts can be prepared by using sodium or potassium 2-ethylhexanoate.

The compounds of formula (I) have antibacterial activity against either Gram positive or Gram negative bacteria with minimum inhibitor concentrations (MIC's) in vitro from 0.4 to >200 pg/ml. The MIC's in ug/ml for /7 - (0) - (-) ? mandelamido -3-(3- sulfomethyl - 1,2,4 - triazol - 5 ylthiomethyl) - 3 - cephem - 4 - carboxylic acid, disodium salt, dihydrate (A) and 7 - D - mandelamido -3-(5- sulfomethyl - 1,3,4 - thiadiazol - 2 ylthiomethyl) - 3 - cephem - 4 - carboxylic acid, disodium salt tetrahydrate (B) are given below:8 6 6 6 S. aureus HH 127 A 3.1 B 1.6 Cefazolin 0.4 S. aureus SK 23390 3.1 0.4 0.2 S. aureus villaluz SK 70390 >200 200 200 Strep. Faecal is HH 34358 200 25 6.3 E. coli SK 12141 0.8 0.4 0.8 E. coli HH 33779 1.6 0.8 l.S Kleb. pneumo. SK 4200 0.8 0.4 1.6 Kleb. pneumo SK 1220 0.4 0.4 0.4 Salmonella ATCC 12176 0.8 0.4 0.8 Pseudo, aeru. HH 63 >200 >200 >200 serratia marc. ATCC 13880 25 25 >200 Proteus raorgani 179 25 (12.5) 1.6 200 Entero. aerog. ATCC 13048 3.1 1.6 1.6 Entero. cloacae HH 31254 1.6 0.4 0.8 Proteus mirabilis PH-444 0.8 0.4 3.1 Compound A gave an EDg0 in mice of 1.02 mg/kg (s.c.) and mg/kg (p.o. against E. coli, 1.02 mg/kg against Kleb. pneumo, (s.c.). Cephalexin gives comparable values of 12.5 (s.c.) and 25 (p.o.) against E. coli. Cephaloridine gives a comparable value of 6.25 (s.c.) against Kleb. pneumo.

Compound B gave an EDgg in mice of 0.3 and 0.33 mg/kg against E. coli as wall as 0.78 and 0.62 mg/kg against Kleb. pneumo (s.c.); and 10 mg/kg against E. coli as well as 8.7 and 8.5 mg/kg against Kleb. pneumo (p.o.). 6 The invention further provides a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable salt or ester thereof and a pharmaceutically acceptable carrier.

The composition can be in the form suitable for oral or parenteral administration. Preferably the composition is in a form suitable for administration by intravenous or intramuscular injection, e.g. a sterile solution or suspension.

The compound of formula (I) or a pharmaceutically acceptable salt or ester thereof is present in such compositions in an effective non-toxic amount.

Preferably the composition is in unit dosage form and containing from 100 to 500 mg of the compound of formula (I) or a pharmaceutically acceptable salt or ester thereof calculated as the free acid.

The compositions of this invention can be prepared by mixing the compound of formula (I) or pharmaceutically acceptable salt or ester thereof with a pharmaceutically acceptable carrier in the same manner as prior art cephalosporins are formulated.

In use the dosage administered is dependent upon the age and weight of the subject and on the susceptibility of the infection being treated.

This can be determined by those skilled in the art based on the data disclosed herein compared with that available to the art attained with the known cephalosporins outlined herebefore. Usually the daily dose is from about 500 mg to 6 g.

The invention further provides a method of treating a bacterial infection in a non-human animal which comprises administering to an infected animal a compound of formula (I) above or a pharmaceutically acceptable salt or ester thereof.

The following Examples where temperatures are in Centrigrade, illustrate the invention.

EXAMPLt.l A mixture of 15.8 g (0.1 mol) of potassium sulfite in 10 ml of watei and 12.2 g (0.1 mol) ethyl chloroacetate in 50 ml of ethanol was warmed at gentle reflux for 4 hours then stirred at room temperature overnight.

The solid was collected, washed with ethanol and air-dried to give potassium ethoxycarbonylmethane sulfonate (Beilstein 4, II, 532), m.p. 213-218°.

A mixture of 17.3 g (0.84 mol) of the methanesulfonate in 840 ml of water with 37.8 g (36.8 ml, 1.18 mol) of hydrazine was heated at reflux overnight. The solution was evaporated to a syrup which began tc crystallize partially. The syrup was dissolved in 300 ml warm water, filtered, arid methanol was added to the filtrate. Scratching gave crystals which were die desired potassium hydrazinocarbonylmethanesulfonate.

Tne hydrazide (19.2 g, 0.1 mole) and 16.5 (0.1 mol) of ethoxycarbonyl di thiocarbamate were mixed with 250 ml of 1:1 water-ethanol and heated at ref'iv:; overnight. The mixture was taken to pH 10-11 with 10% aqueous sodium hydroxide and heated on a steam bath for 1 hour. After cooling overnight the solution was evaporated to dryness. The residue was taken up in warn dimethylformamide. The insoluble materials were collected. The filtrate was evaporated to a heavy oil which was treated with methanol to give a solid. A second crop was also obtained to give, with m.p. 318-5° - 319.5°, the hydrated sodium salt of 5 - mercapto 1,2,4 - triazole - 3 - methanesulfonic acid or 3 - sulfomethyl - 1,2,4 criazole - 5 - thiol. Treatment of an aqueous solution of the salt with a strongly acidic ion-exchange rasin, followed by lyophilization, 45386 gives the acid. This acid and its alkali metal salts such as the sodium or potassium salts are important new intermediates. In this and in the following example the intermediates in their thiol state actually exist mostly as the tautomeric thiones. For convenience the term thiol is used here.

A mixture of 6.4 g (0.015 mol) of 7 - D - (-) - mandelamidocephalosporanic acid and 2.21 g (0.01 mol) of 3 - sulfomethyl - 1,2,4 - triazol - 5 thiol sodium salt, one quarter hydrate in 75 ml of water was taken to pH 6.8 with solid sodium bicarbonate. The solution was stirred at 67° for 6 hours. The mixture was layered with ethyl acetate, then acidified to pH 1.5 with 6N sulfuric acid. The layers were separated.

The aqueous layer was re-extracted wtih ethyl acetate. The acqueous phase was adjusted to pH 6.8 for overnight storage, then taken to pH 1.8 prior to passing over an *Amberlite XAD-7 resin column (a crosslinked o polymer of acrylic esters with an average pore diameter of 80 A). Elution with water gave a series of product-containing eluates which were combined and evaporated. The syrup left after evaporation was taken up in 75 ml of water and lyophilized.

The lyophilizate was then taken up in 12.5 ml of methanol. After filtration, the filtrate was evaporated to half-volume then treated with diethyl ether to precipitate a solid which was dissolved in water and lyophilized to give a fluffy white solid, 7 - 0-(-)- mandelamido 3-(3- sulfomethyl - 1,2,4 - triazol - 5 - thiomethyl) - 3 - cephem 4 - carboxylic acid disodium salt dihydrate.

Anal. Calculated: C, 36.71; H, 3.40; N 11.25 Found: C, 36.89; H, 3.83; N, 11.32 *Amberlite is a trade mark.

EXAMPLE 2 A solution of 15.5 (O.l mol) of £ - methoxybenzyl chloride in 25 ml of ethanol was added dropwise to a solution of 14.6 g (0.1 mol) of potassium dithiocarbazate in 200 ml of 1:1 aqueous ethanol. After stirring for 2 hours at room temperature, the mixture was cooled in an ice bath to precipitate 16.4 g of the desired product, £ methoxybenzyl dithiocarbazate, m.p. 138.5 - 140° after recrystallization from chloroform.

Anal. Calcd.: C, 47.34; H, 5.30; N, 12.27 Found: C, 47.55; H, 5.32; N, 12.59 A solution of 6.15 g (0.055 mol) of chloroacetyl chloride in 50 ml cf dry benzene was added dropwise to a suspension of 11.4 g of the dithiocarbazate in 250 ml of benzene. Tne mixture was stirred at room temperature, then heated at reflux for 4 hours over a water trap. The coded reaction mixture was washed with water, dilute sodium bicarbonate, then water. The dried organic layers were evaporated to leave a yellow oil which crystallized upon standing. The solid was purified b.y extraction with hot hexane (6 x 150 ml). The soluble material obtained after evaporation of the hexane extracts was crystallized using methylene chloride-hexane to give 9.15 g of the desired 2-(£-methoxybenzylthio) - 5 - chloromethyl - 1,3,4 thiadiazole, m.p. 60.5 - 63.5°.

Anal. Calcd.: C 46,07; H, 3,87; N, 9.77 Found: C 46.33; H, 4.04; N, 9.78 A mixture of 13.0 g of the chloromethylthiadiazole in 250 ml of tetrahydrofuran and 5.73 g of sodium sulfite in 50 ml of water was heated at reflux overnight. Since reaction was not complete, a solution of 2.86 g of sodium sulfite in 100 ml of water was further added, followed by refluxing overnight. The mixture was then evaporated. The residue was extracted into 275 ml of warm water which was extracted with ethyl ether. The aqueous phase was evaporated to about 200 ml volume. Cooling gave 8.6 g of white platelets of the desired 5 - (£- methoxybenzylthio) - 1,3,4 - thiadiazole - 2 methanesulfonic acid, sodium salt.

A solution of 31.2 g (0.091 mol) of mercuric acetate in 240 ml of vzater was added to a solution of 11.6 g of thio compound prepared immediately above in 480 ml of methanol and 125 ml of water. After 1.5 hours the mixture was treated with hydrogen sulfide until it was completely black. The mixture was evaporated, methanol was added and the black solid was removed by filtration. Evaporation of the methanol solution gave a crystalline solid vzhich was purified by reorystallization from water-propanol.

A second crop can be isolated from the filtrate to give a total of 5.18 g (68%), m.p. 293°, of 5 - mercapto - 1,3,4 - thiadiazole - 2 - methanesulfonic acid or 5 - sulfomethyl - 1,3,4 - thiadiazole - 2 - thiol as the sodium salt. The parent acid may be obtained by passing an aqueous solution of the sodium salt down a column of strongly acidic ion-exchange resin and than evaporating the water.

Other alkali metal salts may be prepared from the acid, such as the potassium salt using potassium methoxide-methanol. These are new intermediate compounds and are part of this invention. 6 8 6 A solution of 6.4 g (0.015 mol) of 7 - 0 - mandelatnidocephalosporanic acid sodium salt and 2.3 g (0.01 mol) of the thiol salt in 75 ml of water was treated with sodium bicarbonate to pH 6.7. The mixture was warmed at 68° for 5 hours. The cooled mixture was taken to pH 2.0 with 6N sulfuric acid after addition of ethyl acetate. The mixture was extracted twice with ethyl acetate. The remaining aqueous phase was passed through an Amberite XAD-7 column (a cross-linked) polymer o of acrylic esters with an average pore diameter of 80 A) with elution with water. The product-containing eluates were combined and evaporated.

The solid was put on a column of cellulose powder in 80:20 acetonitrile: water. Acetonitrile was evaporated from the product-containing eluates leaving an aqueous solution which was then passed over Amberlite IR-120HCP resin. The acidified solution was titrated from pH 2.0 to pH 6.5 with 2% sodium hydroxide solution. The solution was filtered and lyophilized to give 7 - Q - (-)- mandelamidoj -3-(5sulfomethyi - 1,3,4 - thiadiazol - 2 - ylthiomethyl) - 3 - cephem - 4 carboxylic acid, disodium salt tetrahydrate.

Anal. Calcd.: C, 33.82; H, 3.59; N, 8.30 Found: C, 34.08; H, 3.44; N, 8.14 EXAMPLE 3 A mixture of 5.22 g (10.0 mmol) of 7-(D-o-t - butoxycarbonyl ami no - 4 - hydroxyphenylacetanildojcepbalosporanic acid and an excess (15.0 mmol) of 3 - sulfomethyl - 1,2,4 - triazo - 5 - thiol in 75 ml of pH 6.4 phosphate buffer solution is treated with sufficient sodium bicarbonate to give a s6S® pH of 6.4. The mixture is heated at 70° for 3 hours, cooled, acidified with dilute hydrochloric acid to pH 2 and extracted with ethyl acetate. The aqueous solution is adjusted to pH 7.0 with sodium bicarbonate aqd added to an Amberite XAD-7 resin column. Elution with water and then methanol, followed by evaporation of the productcontaining fractions, gives the t-boc (t-butoxycarbonyl)derivative of the desired compound. This derivative is stirred at 25°C. with 25 ml of trifluoroacetic acid and 25 ml of 1,3 - dimethoxybenzene for 2 hours. The mixture is evaporated to dryness, ether added to the residue and the precipitated salt collected. This is dissolved in water and one molecular equivalent of sodium bicarbonate is added.

The solution is hyophilized and then tritrated with acetone to give 7 - (D - a - amino - 4 - hydroxyphenylacetamido) -3-(3- sulfomethyl 1,2,4 - triazol - 5 - ylthiomethyl) - 3 - cephem - 4 - carboxylic acid.

Similar treatment of the t-boc derivative of 7 - DL (a - amino phenylacetamidocephalosporanic acid gives the corresponding 7 - DL - (a - ami nophenyl acetamido) -3-(3- sulfomethyl - 1,2,4 triazol - 5 - ylthiomethyl) - 3 - cephem - 4 - carboxylic acid.

EXAMPLE 4 A mixture of an excess (12.2 mmol) of 3 - sulfomethyl - 1,2,4 triazol - 5 - thiol, 32.5 mmol of sodium bicarbonate and 8.1 mmol of trifluoromethylthioacetamidocephalosporanic acid in 50 ml of water is stirred at 70° for 5 hours. The reaction mixture is cooled and passed over Amberlite XAD-2 resin with water and methanol as eluants, The methanol eluants are evaporated to dryness to give a residue which is S 6 S 6 dissolved in a small amount of water and lyophilized to give 7 - trifluororaethylthioacetamido --3-(3- sulfomethyl - 1,2,4 - triazol 5 - ylthiomethyl) - 3 - cephem - 4 - carboxylic acid di sodium salt. Substituting 7-(2- thienylacetamidocephalosporanic acid gives 7-(2- thi enyl acetamido) -3-(3- sulfomethyl - 1,2,4 - triazol 5 - ylthiomethyl) - 3 - cephem - 4 - carboxylic acid disodium salt.

Stoichiometric quantities of cephalosporanic acids having the individual 7 - acylamino substituent listed hereabove may be substituted in Examples 1, 3 or 4 with variations which will be obvious to those skilled in this art.

EXAMPLE 5 A mixture of 5.22 g (10.0 mmol) of7-D-a-t - butoxycarbonyl ami no 4 - hydroxyp'nenylacetamido)cephalosporanic acid and an excess (15.0 mmol) of 5 -· sulfomethyl - 1,3,4 - thiadiazole - 2 - thiol in 75 ml of IE gH 6.4 phosphate buffer solution is treated with sufficient sodium bicarbonate to give a pH of 6.4. The mixture is heated at 70° for 3 hours, cooled, acidified with dilute hydrochloric acid to pH 2 and extracted with ethyl acetate. The aqueous solution is adjusted to pH 7.0 with sodium bicarbonate and added to an Amberlite XAD-7 column. Elution with water and then methanol, followed by evaporation of the product-containing fractions gives ths t-boc derivative of the desired compounds as its disodium salt. This derivative is stirred at 25°C. with 25 ml of trifluoroacetic acid and 25 ml of 1.,3 - dimethoxybenzene for 2 hours.

The mixture is evaporated to dryness, ether added to the residue and the precipitated salt collected. This is dissolved in water, and one molecular equivalent of sodium bicarbonate is added. The solution is lyophilized and than triturated with acetone to give 6 8 6 - D - α - amino - 4 - hydroxyphenylacetamido) -3-(5- sulfomethyl 1„3,4 - thiadiazol - 2 - ylthiomethyl) - 3 - eephem - 4 - carboxylic acid. Similar treatment of the t-boc derivative of the 7-DL-(«aminophenylacetamidocephalosporanic acid gives the corresponding 7 - DL 5 (a - ami nophenyl acetamido) -3-(5- sulfomethyl - 1,3,4 - thiadiazol 2 - ylthiomethyl) - 3 - eephem - 4 - carboxylic acid.

EXAMPLE 6 A mixture of an excess (12.2 mmol) of 5 -sulfomethyl - 1,3,4 thiadiazole - 2 - thiol, 32.5 mol of sodium bicarbonate and 8.1 mmol of 7 - trifluoromethylthioacetamidocephalosporanic acid in 50 ml of water is stirred at 70° for 5 hours. The reaction mixture is cooled and passed over Amberlite XAD-2 resin with water and methanol as eluants.

The methanol eluants are evaporated to dryness to give a residue which is dissolved in a small amount of water and lyophilized to give 7 - trifluoromethylthioacetamido -3-(5- sulfomethyl - 1,3,4 - thiadiazol - 2 - ylthiomethyl) - 3 - eephem - 4 - carboxylic acid disodium salt. Substituting 7-(2- thienyl acetamido) - cephalosporanic acid gives 7-(2- thienylacetamido) -3-(5- sulfomethyl - 1,3,4 - thiadiazol 2 - ylthiomethyl) - 3 - eephem - 4 - carboxylic acid disodium salt.

EXAMPLE 7 An injectable pharmaceutical composition is formed by adding sterile saline solution (2 ml) to 500 ml of the product of either Example 1 or 2. This material is injected parenterally four times daily in to a human patient infected with susceptible bacteria. Other compounds of this invention may be similarly used.

Claims (27)

1. A compound of formula (I) :- and pharmaceutically acceptable salts, esters thereof where Ac is a pharmaceutically acceptable acyl group as' defined herein and is hydrogen or methoxy and E is -Ξ- or -NH-.

2. A compound as claimed in claim 1 where Ac is 0 0 0 i 11 XCHC-, YCH-C- or ZS(O) CH-Cj 2 m2 i A wherein X is thienyl, furyl, phenyl or phenyl monosubstituted with hydroxy, hydroxymethyl, formamido or ureido; A is ”NH 2 , -OH, -COOH, -SO 3 H, formyloxy or, methoxyimino (the α-C-hydrogen then being absent); Y is cyano, sydnonyl, pyridonyl, thienyl, aminomethylphenyl, phenyl or tetrazolyl; Z is methyl, trifluoromethyl, trifluoroethyl, pyridyl or cyanomethyl; and m is zero one or two. 1

3. A compound as claimed in claim 1 or claim 2 where E is -S-.

4. A compound as claimed in claim 1 or claim 2 where E is -NH-.

5. The D form of a compound as claimed in any one of claims 1 to 4 having as asymmetric group Ac.

6. 7-D-(-)Mandelamido-3-(3-sulfomethyl-l,2,4-triazol 10 -5-thiomethyl)-3-cephem-4-carboxylic acid.

7. 7- D-(-)-Mandelamido -3-(5-sulfomethyl-l,3,4thiadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid. 15

8. 7-(D-a-Amino-4-hydroxyphenylacetamido)-3-(3sulfomethyl-1,2,4-triazol-5-thiomethyl)-3-cephem-4-carboxylic acid,

9. , 7-DL-(a-Aminophenylacetamido)-3-(3-sulfomethyl-l, 20 2,4-triazol-5-yl.thiomethyl)-3-cephem-4-carboxylic acid.

10. 7-Trifluoromethy!’£hioacetamido-3-(sulfomethyl1, 2,4 -triazol-5-yl thiomethyl) -3-cephem-4-carboxylic acid. 25

11. 7-(2-Thienylacetamido)-3-(3-sulfomethyl-l,2,4triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid.

12. 7-D-(o-Amino-4-hydroxyphenylacetamido)-3-{5sulfomethyl-1,3,4-thiadiazol-2-ylthiomethyl)-3-cephem-430 carboxylic acid.

13. 7-DL-(a-AminophenylacetamidO)-3-(5-sulfomethyl1,3,4-thiadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid.

14. 7-Trifluoromethylthioacetamido-3-(5-sulfomethyl1,3,4-thiadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid. £<> -’o 413 6 S 6 1

15. 7-(2-Thienylacetamido)-3-(5-sulfomet.hyl-l,3,4thiadiazol-2-ylthiomethyl)-3-cephem-4-carboxylic acid,

16. The sodium salt of a compound of formula (I) as claimed in any one of the claims 1 to 15.

17. An indanyl, pivaloyloxymethyl, acetoxymethyl, propionyloxymethyl, glycyloxymethyl, phenylglycyloxymathyl or thienylglycyloxymethyl ester of a compound of formula (I) as claimed in any one of claims 1 to 15.

18. A process for preparing a compound as claimed in claim 1 which comprises reacting a compound of formula (II) :- or a salt thereof where Ac and R^ are ad defined with 25 reference to formula (I) and in which any carboxy, amino, sulfo, or hydroxy groups are optionally protected, with a thiol of formula (III) :30 HS ch 2 so 3 h where E is as defined with reference to formula (I) and in which the sulfo group is optionally protected or a salt thereoj., optionally converting the group when It is hydrogen (III) 48686 into methoxy by a known method, removing any protecting groups and optionally converting the product so obtained into a salt or ester.

19. A process for preparing a compound as claimed in claim 1 which comprises reacting a compound of formula (IV) :10 ch 2 s· (IV) ch 2 so 3 h where E is as defined with reference to formula (I) and in which any carboxyl or sulfo groups are optionally protected with any acylating agent capable of supplying the acyl moiety Ac in which any carboxyl, amino, sulfo, or hydroxy groups are optionally protected, optionally converting the group R 1 when it is hydrogen into methoxy by a known method, removing any protecting groups, and optionally converting the product so obtained into an ester or salt.

20. A process as described herein as claimed in claim 18 in any one of Examples substantially 1 to 6.

21. A compound as claimed in claim 1 whenever prepared by a process as claimed in any one of claims 18 to 20. 30

22. A pharmaceutically composition comprising a compound of formula (I) as claimed in claim 1 or a pharmaceutically acceptable ester or salt' thereof and a pharmaceutically acceptable carrier. 35

23. A composition as claimed in claim 22 4 5 6 3 6 in a form suitable for intravenous or intramuscular injection. .

24. A composition as claimed in claim 23 substantially as described in Example 7 herein.

25. A process for preparing a composition as claimed in claims 22 or 23, which comprises mixing a compound of formula (I) as claimed in claim 1 or a pharmaceutically acceptable salt or ester thereof with a pharmaceutically acceptable carrier. a

26. A process for preparing/composition as claimed in claim 25 substantially as described in Example 7 herein.

27. A method of treating a bacterial infection in a non-human animal which comprises adminstering to an infected animal a compound of formula (I) as claimed in claim 1 or a pharmaceutically acceptable salt or ester thereof.