Practical synthesis of α-aminoalkyl-α′-chloromethylketone derivatives. Part 2: Chloromethylation of N-imine-protected amino acid esters

Chloromethylation of N-imine-protected amino acid esters followed by acid hydrolysis gave α-aminoalkyl-α′-chloromethylketone as a HCl salt form in good yield without racemization. The amino group was conveniently protected with carbamate protecting reagents to give various useful intermediates for the protease inhibitors.