Patent ID: 7345169

Claim:
A process for the preparation of Ceftiofur of formula (I) or its salt the process consisting of: (i) activating the compound of formula (III) into a compound of formula (IIIa) in an organic solvent where X represents a halogen atom, using a halogenating agent, (ii) treating a reaction mass obtained from step (i) at a temperature in a range of −40° C. to 10° C. with water, (iii) separating an organic layer containing an activated derivative of formula (IIIa) and directly condensing the activated derivative of the formula (IIIa) where X represents a halogen atom, with 7-amino cephalosporin derivative of formula (II) or a trimethylsilyl reactive derivative of formula (II), wherein the organic layer from step (ii) containing the activated derivative of formula (IIIa) is condensed with a 7-amino cephalosporin derivative wherein R′ represents hydrogen or trimethylsilyl, and R″ represents hydrogen or trimethylsilyl, in the presence of a solvent and in the presence or absence of a base at a temperature in a range of −50° C. to 10° C. to produce a compound of formula (IV) where all symbols are as defined above, and iv) cyclizing the compound of formula (IV) with thiourea in the presence of water and in the presence or absence of a water miscible solvent and base at a temperature in a range of −50 to 30° C. to produce the compound of formula (I), wherein producing the compound of formula (I) occurs without isolating the compound of formula (IV) or its salt, and conducting the reaction of step (iv) in a homogeneous solvent system.