t-Butyl (6R,7R)-7-phenylacetamido-3-[(RS)-tetrahydrofuran-3-yl]ceph-3-em-4-carboxylate (0.9 g) in dichloromethane (15 ml) with N-methylmorpholine (0.45 g, 0.49 ml) was successively treated with phosphorus pentachloride (0.549 g) in dichloromethane (13.74 ml), methanol (10 ml) and water (10 ml) as described in Example 2(f). After purification by flash chromatography on silica gel eluting with 60, 80% ethyl acetate/hexane and then ethyl acetate, the title compound was obtained as a yellow solid (0.481 g, 73%); (Found: M+, 326.1304. C15H22N2O4S requires M, 326.1300); νmax (CH2Cl2) 3408, 1775 and 1716 cm-1 ; δH (CDCl3) 1.55 (9H, s), 1.69-2.41 (3H, m's), 3.31 and 3.48 with 3.34 and 3.49 (2H, 2ABq's, J 17.5 and 17.5 Hz), 3.69-3.83 (4H, 2s's overlapping m), 3.97-4.05 (2H, m), 4.72 and 4.74 (1H, 2d's, J 4.3 and 4.4 Hz) and 4.95 and 4.97 (1H, 2d's, J 4.3 and 4.4 Hz).
