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

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Reaction Steps

An ozone/oxygen stream (0.5 mmol per minute) is passed for 7 minutes into a solution, cooled to -70° C., of 2.30 g (3.0 mmols) of 2-[4-(p-toluenesulphonylthio)-3-(α-tert.butoxycarbonylamino-α-phenylacetylamino)-2-oxoazetidin-1-yl]-3-methylene-butyric acid diphenylmethyl ester in 230 ml of methylene chloride. After adding 1 ml of dimethyl sulphide, the solution is stirred for a further hour without cooling and is then concentrated by evaporation in vacuo. The residue is recrystallised from methylene chloride/ether/hexane and gives 2-[4-(p-toluenesulphonylthio)-3-(α-tert.butoxycarbonylamino-α-phenylacetylamino)-2-oxoazetidin-1-yl]-3-hydroxy-crotonic acid diphenylmethyl ester of melting point 182°-184° C; UV spectrum (ethanol): λmax =259 mμ (ε=13,400); IR spectrum (methylene chloride): characteristic bands at 2.92, 5.59, 5.83, 5.92, 6.03 (shoulder), 6.18 and 6.68μ; thin layer chromatogram: Rf value~0.55 (silica gel; toluene/ethyl acetate, 1:1).

Provenance & Evidence