Process for the preparation of tazobactam

An improved process for the preparation of Tazobactam of formula (I)

• which comprises the steps of:
• i) reacting compound of formula (II)
• wherein R is selected from p-methoxybenzyl, diphenylmethyl(benzhydryl), 3,4,5-tirmethoxybenzyl, 2,4-dimethoxybenzyl, 3,5-dimethoxy-4-hydroxybenzyl, 2,4,6-trimethylbenzyl, ditolylmethyl, dianisylmethyl or tert-butyl with mercaptan of formula R′−SH in the presence of an organic solvent to get compound of formula (III);
• wherein R has the meaning given above and R′ is selected from benzothiazol-2-yl, benzoxazol-2-yl, benzimidazol-2-yl, 5-methyltetrazol-2-yl,
• ii) converting the compound of formula (III) to compound of formula (IV)
• wherein R has the meaning given above and X represents a leaving group selected from the group consisting of chloro, bromo, iodo, mesylate, tosylate, besylate and triflate in the presence or absence of second organic solvent and phase transfer catalyst;
• iii) converting the compound of formula (IV) to compound of formula (V);
• wherein R has the meaning given above;
• iv) oxidizing compound of formula (V) to get compound of formula (VI);
• wherein R has the meaning given above;
• v) deprotecting compound of formula (VI) with cresol to get tazobactam of formula (I);
• and
• vi) extracting the tazobactam of formula (I) into aqueous layer optionally using base;
• vii) acidifying the solution to yield Tazobactam of formula (I);
• wherein the improvement consists of either or both of the following
• a) carrying out steps (i) to (iii) in situ and without isolating the intermediates (III) and (IV);
• b) acidification in step (vii) is carried out in the presence of water-miscible solvent.