Patent ID: 7230097

Claim:
A process for preparation of Cefprozil of formula (I) in the form of a monohydrate, the process comprising: condensing a mixed acid anhydride of α-amino-p-hydroxy phenylacetic acid of formula (III) wherein R 1 is an alkyl or an aryl group, and R 2 is methyl or ethyl, with a protected 7-amino-3-(propen-1-yl)-3-cephem-4-carboxylic acid of formula (VII) (III) wherein R 3 and R 4 are protective groups, and R is propen-1-yl, followed by hydrolysis, isolation and purification to give Cefprozil of formula (I) in the form of a monohydrate, wherein the mixed anhydride of formula (III) is prepared by a process comprising the steps of (a) adding ethyl chloroformate and a base to a mixture of an inert organic solvent and a polar aprotic solvent at a temperature in the range of 0° to 40° C.; (b) cooling the solution to a temperature in the range of −70° to −30° C.; (c) addition of Dane salt of an α-amino-p-hydroxy phenyl acetic acid to the cooled solution and agitation at a temperature in the range of −70° to −30° C.