4-Toluenesulfonyl chloride → Zofenopril Impurity 4

참여 물질

반응 단계

37.5 ml (270 mmol) of triethylamine, 49.04 g (257 mmol) of p-toluenesulfonyl chloride and 2.99 g (24.5 mmol) of 4-dimethylaminopyridine were added in turn to a solution of 77.70 g (245 mmol) of (2S,4R)-1-benzyloxycarbonyl-4-hydroxyproline methyl ester in 600 ml of methylene chloride, and the resulting mixture was then stirred at room temperature overnight. At the end of this time, the reaction mixture was concentrated by evaporation under reduced pressure and the residue was partitioned between ethyl acetate and water. The organic extract was washed with water, dried over anhydrous magnesium sulfate and then concentrated by evaporation under reduced pressure. The resulting residue was purified by chromatography on a silica gel column using a 1:1 by volume mixture of hexane and ethyl acetate as the eluant to afford 106.18 g (quantitative yield) of (2S,4R)-1-benzyloxycarbonyl-4-(p-toluenesulfonyloxy)proline methyl ester as a yellow oil.

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