A New Synthesis of Methionine5-Enkephalin

Central Drug Research Institute, Lucknow 226 001

Synthesis of the endogenous opiate, methionines⁵-enkephalin, by stepwise elongation of the peptide chain from C-terminus using 2,4,5-trichiorophenyl active esters of t-butoxycarbonyl amino acids is described. The preparation of intermediate peptides Boc-Gly-Phe-Met-OMe * (2), Boc-Gly-Gly-Phe-Met-OMe* (2), Boc-Tyr-Gly-Gly-Phe-O­Me (3) and Boc-Tyr-Gly-Gly-Phe-Met Ome(5) in high yields is also reported.