19.64 ml (0.242 mol) of pyridine are added to a suspension of 50 g (0.0972 mol) of benzhydryl 7-phenylacetamido-3-hydroxymethyl-3-cephem-4-carboxylate in 500 ml of methylene chloride at room temperature. After cooling to -20° C., 40.48 g (0.0972 mol) of phosphorus pentachloride are added and the mixture is stirred at -20° C. for 5 minutes. The mixture is warmed to 0° C. with an icebath and stirred for 10 minutes, and is then warmed to 15° C. with a waterbath and stirred for 1 hour. Thereafter, the mixture is cooled to -70° C. and 720 ml of cold methanol are quickly added The mixture is then stirred at -70° C. for 5 minutes, at 0° C. for 10 minutes and at +15° C. for 25 minutes. The solution is subsequently concentrated to a high degree in vacuo and 1,400 ml of saturated sodium bicarbonate solution are added. The solution is extracted three times with methylene chloride and the organic phase is dried with sodium sulphate and concentrated in vacuo. The crude product is chromatographed on 500 g of silica gel 60 (0.04-0.063 mm) with methylene chloride.
