m-Chloroperbenzoic acid → 2-Benzhydryloxycarbonyl-7-t-butoxycarbonylamino-8-oxo-3-(2-tosyloxyvinyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-5-oxide

Participants

Reaction Steps

A solution of 85% pure m-chloroperbenzoic acid (55.22 g) in methylene chloride (600 cc) is added dropwise, in the course of 2 hours, to a solution, cooled to -10° C., of 2-benzhydryloxycarbonyl-7-t-butoxycarbonylamino-8-oxo-3-(2-tosyloxyvinyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene (or -3-ene) (mixture of the E and Z forms) (180.56 g) in methylene chloride (1.4 liters). The mixture is washed with a 5% strength solution of sodium bicarbonate (1.5 liters) and water (2×1.5 liters), dried over sodium sulphate and concentrated at 20° C. under reduced pressure (20 mm Hg; 2.7 kPa) to a volume of 300 cc. This solution is chromatographed on a column of Merck silica gel (0.05-0.2) (3 kg) (diameter of the column: 9.2 cm; height: 145 cm). Elution is carried out successively with the following mixtures of cyclohexane and ethyl acetate: 80/20 (by volume) (15 liters) and 70/30 (by volume) (32 liters), 600 cc fractions being collected. Fractions 27 and 28 are collected and evaporated and this yields the Z form of 2-benzhydryloxycarbonyl-7-t-butoxycarbonylamino-8-oxo-3-(2-tosyloxyvinyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-5-oxide (5.56 g).

Provenance & Evidence