The p-methoxybenzyl ester group in peptide synthesis

Abstract

p-Methoxybenzyl esters of protected amino acids and peptides have been prepared by imidazole-promoted condensation of the corresponding p-nitrophenyl esters with p-methoxybenzyl alcohol. The products included several o-nitrophenylsulphenyl dipeptide p-methoxybenzyl esters, and the use of p-methoxybenzyl as a carboxyl-protecting group was illustrated by the synthesis of a protected pentapeptide fragment of a modified insulin A-chain sequence involving selective acidic cleavage of a-nitrophenylsulphenyl.