2-Mercapto-5-phenyl-1,3,4-oxadiazolyl-(Z)-4-bromo-2-methoxyimino-3-oxo-butyrate (46.0 g) was taken in a mixture of tetrahydrofuran (250 ml) and water (150 ml). The solution was cooled to 10° C. and the thiourea (20.47 g) and sodium acetate (4.32 g) were added. The reaction mixture was stirred for 1.0 hr. 7-amino cephalosporanic acid (25.0 g) was added followed by slow addition of triethylamine (20.4 g) the progress of the reaction was monitored by HPLC. The reaction was completed in 6-8 hr. The reaction mixture was extracted with dichloromethane (3×200 ml). The aqueous layer was acidified with dil. HCl to obtain cefotaxime, 38.0 g.
