Deprotection of O-methyltyrosine by a ‘push–pull’ mechanism using the thioanisole–trifluoromethanesulphonic acid system. Application to the convenient synthesis of a potent N-methylenkephalin derivative

Abstract

The methyl group attached at the phenolic oxygen of tyrosine can be smoothly cleaved by a thioanisole–trifluoromethanesulphonic acid system; this deblocking method was successfully applied to the synthesis of a new potent enkephalin derivative, MeTyr-Gly-Gly-Phe-Metol (Metol = L-methioninol residue).