FOERFARANDE FOER FRAMSTAELLNING AV EN ANTIBIOTISKT VERKANDE 7-ETA-ACYLAMIDOCEF-3-EM-4-KARBOXYLSYRA

A procedure for the preparation of antibiotic cephalosporin compounds of the general formula: **(See formula)** (where R is thienyl or furyl; Ra and Rb, which may be the same or different, are each selected from hydrogen, C1-4 alcohol, C3-7 cycloalkyl alkenyl, phenyl, naphthyl, thienyl, furyl, carboxy, C2-5 alkoxycarbonyl and cyano; or Ra and Rb together with the carbon atom to which they are attached form a C3-7 cycloalkoxynyl or cycloalkenylidene group; m and n are each 0 or 1 such that the sum of m and n is 0 or 1; and Y is the residue of a nucleophile or a derivative of the residue of a nucleophile or its non-toxic derivatives, said compounds being a isomer without or presenting as a mixture of the sin and anti isomers containing at least 90% of the sin isomer, characterized in that a compound of the formula is reacted **(See formula)** (Where B, R, Ra, Rb, m and n are as defined above each can independently represent hydrogen or a carboxyl blocking group; Y1 is a substitutable residue of a nucleophile; and the dotted line joining the 2 positions, 3 and 4 indicate that the compound is a cef-2-em or cef-3-em) compound with a nucleophile; after which, if necessary and/or if desired in each case, some of the following reactions are carried out in any appropriate sequence: i) conversion of an isomer (see formula) to the desired isomer (see formula), ii) reduction of a compound where B is (see formula) to form a compound where B is> S; iii) reduction of a 3-azidomethyl compound to form a 3-aminomethyl compound; iv) acylation of a 3-aminomethyl compound to form a 3-acylaminomethyl compound; v) reacting a 3-azidomethyl compound with a dipolarphile to form a compound having a polyazole ring attached to the 3-position carbon atom via a methylene group; vi) deacylation of a 3-acyloxymethyl compound to form a 3-hydroxymethyl compound; vii) acylation of a 3-bldroxymethyl compound to form a 3-acyloxymethyl compound, viii) carbamoylation of a 3-hydroxymethyl compound to form an unsubstituted or substituted 3-carbamoyloxymethyl compound, and ix) separation of groups of carboxyl block; and finally recover the desired compound of formula I or its non-toxic derivative, if necessary after separation of the isomers. (Machine-translation by Google Translate, not legally binding)