Diazomethane → 2-[4-(p-Toluenesulphonylthio)-3-(alpha-tert.butoxycarbonylamino-alpha-phenylacetylamino)-2-oxoazetidin-1-yl]-3-methoxy-crotonic acid diphenylmethyl ester

Participants

Reaction Steps

A solution of 0.54 g (0.7 mmol) of 2-[4-(p-toluenesulphonylthio)-3-(α-tert.butoxycarbonylamino-α-phenylacetylamino)-2-oxoazetidin-1-yl]-3-hydroxy-crotonic acid diphenylmethyl ester in 20 ml of methylene chloride/methanol, 1:1, is stirred for 15 minutes with an excess of a solution of diazomethane in ether at 0° C. and is then concentrated by evaporation in vacuo. Preparative layer chromatography of the residue on silica gel, using toluene/ethyl acetate, 1:1, as the running agent, and elution of the zone which is visible in UV light gives 2-[4-(p-toluenesulphonylthio)-3-(α-tert.butoxycarbonylamino-α-phenylacetylamino)-2-oxoazetidin-1-yl]-3-methoxy-crotonic acid diphenylmethyl ester, which is recrystallised from methylene chloride/diethyl ether/hexane.

Provenance & Evidence