Diphenylmethyl 3-(2-oxotetrahydrofuran-3-ylthio)-7β-phenylacetamidoceph-3-em-4-carboxylate (733 mg) was suspended in dry dichloromethane (10 ml) under an inert atmosphere. The reaction was cooled to -20° C. and treated with N-methylmorpholine (269 μl) followed by a solution of phosphorus pentachloride in dichloromethane (9.5 ml of 40 mgml-1 solution). The now homogeneous solution was stirred at -20° C. for 30 min. Treated with methanol (2.44 ml) and then continued stirring whilst allowing to warm to room temperature. After 30 min. water (3.3 ml) was added and the solution vigorously stirred for a final 30 min. The organic solvent was removed by evaporation in vacuo. The resulting solid was removed from the aqueous phase by filtration and was washed with water and then ether. Drying the solid over phosphorus pentoxide in vacuo gave the crude title compound in the form of its hydrochloride (621 mg). (c) Diphenylmethyl 3-(2-Oxotetrahydrofuran-3-ylthio)-7β-[2-(2-tritylaminothiazol-4-yl)-2-(Z)-methoxyiminoacetamido]ceph-3-em-4-carboxylate.
