A stirred solution of 2-(2-tritylaminothiazol-4-yl)-2-(Z)-methoxyiminoacetic acid hydrochloride (528 mg) and N,N-diisopropylethylamine (0.383 ml) in dry dimethylformamide (4 ml) was cooled to -55° to -60° C. and methanesulphonyl chloride (0.085 ml) was added. The mixture was stirred at the same temperature for 30 mins, and then diphenylmethyl 7β-amino-3-(2,5-dihydro-2-oxofuran-4-ylthiomethyl)ceph-3-em-4-carboxylate (494 mg), dimethylformamide (2 ml) and pyridine (0.08 ml) were added. The mixture was then stirred at 0° for 90 mins. The mixture was partitioned between ethyl acetate and citric acid solution, and the ethyl acetate phase was washed twice with water, then with saturated sodium bicarbonate solution, then water and finally with brine. The solution was dried over magnesium sulphate and evaporated. The title compound (703 mg) was isolated by column chromatography of the residue using gradient elution (Kieselgel 5:2 going to 3:7 hexane:ethyl acetate). υmax (CHCl3), 3400, 1785, 1745, and 1685cm-1. δH (CDCl3) 3.42 (1H, d, J 18.3Hz), 3.61 (1H, d, J 18.4Hz), 3.89 (1H, d, J 12.6Hz), 4.04 (1H, d, J 12.6Hz), 4.08 (3H, s), 4.71 (2H, s), 5.08 (1H, d, J 5.0Hz), 5.65 (1H, s), 5.97 (1H, dd, J 4.9 and 8.8Hz), 6.73 (1H, s), 6.84 (1H, d, J 8.7Hz), 6.96 (1H, s), 7.03 (1H, s), 7.2-7.45 (25H, m). [mass spectrum: +ve ion (3 NOBA, Na+) M Na+ 942].
