Facile Preparation of N-Tosyl-L-Phenylalanine Chloromethyl Ketone

A method for the facile preparation of N-tosyl-L-phenylalanine chloromethyl ketone was developed. LPhenylalanine was tosylated and converted to the activated ester of p-nitrophenol. Subsequent reaction with dimethylsulfoxonium methylide and treatment with lithium chloride and methanesulfonic acid afforded the α- chloroketone. This practical procedure avoided the use of toxic and explosive diazomethane. Keywords: Serine protease inhibitors, α-chloroketone, N-tosyl-L-phenylalanine chloromethyl ketone, ylides, sulfur