Patent ID: 7662955

Claim:
A process for the preparation of cefoxitin of formula (I) the process comprising: (i) treating a compound of formula (II) wherein Ac represents acetyl, with a halogenating agent in an organic solvent, followed by treatment with an alkali/alkaline earth metal methoxide at a temperature in the range of −100° C. to 0° C., isolating the product formed as an organic amine salt of the formula (III), where M + represents an organic ammonium ion and Ac is as defined above; (ii) treating the salt of formula (III) with a base in the presence of a solvent at a temperature in the range of −75 to 10° C., isolating the product formed as an organic amine salt of formula (IV), where M + represents an organic ammonium ion, (iii) carbamoylating the compound of formula (IV) with an isocyanate of formula (V) RNCO (V) wherein R is a labile group selected from chlorosulphonyl, mono-, di- or tri-chloroacetyl, bromosulphonyl, trichloroethoxycarbonyl, trimethylsilyl or chlorobenzene sulphonyl, in the presence of a solvent at a temperature in the range of −60° C. to 10° C., and isolating to get cefoxitin of formula (I).