Dimethyl Sulfate → 2-[4-(p-Toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-methoxy-isocrotonic acid diphenylmethyl ester

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Reaction Steps

(avi) 3.78 g (30 mmols) of dimethylsulphate and 30 ml of 20 percent strength aqueous potassium bicarbonate solution are added to a suspension of 6.72 g (10 mmols) of 2-[4-(p-toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-hydroxy-crotonic acid diphenylmethyl ester (crystalline) and 0.36 g (1 mmol) of tetera-n-butylammonium iodide in 100 ml of toluene and the mixture is stirred vigorously for 4 hours at room temperature. During the first 15 minutes, the solid dissolves. The mixture is diluted with toluene and washed with saturated aqueous sodium chloride solution. After drying the organic phase with sodium sulphate, and concentrating it, crystallisation from ethyl acetate/diethyl ether gives 2-[4-(p-toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-methoxy-isocrotonic acid diphenylmethyl ester.

Provenance & Evidence