Detosylation of N-Tosyl Amino Acids and Peptides by Electrolytic Reduction

An electrolytic reductive cleavage of tosyl group in N-tosyl amino acids was carried out by the use of 2 mol equivalent of NaCl or KCl as an electrolyte to the tosyl amino acids and of lead as a cathode in methanol–water. The procedure was applicable to the cleavage of N-tosyl peptides with preservation of the peptide bond, and with retention of their optical activity. No cleavage of the other protecting groups such as urethane type group and benzyl group was observed. The optimum conditions for reductive cleavage were found to be pH 11, lead being preferable to other cathode metals.