Preparation of protected peptide hydrazides from the acids and hydrazine by dicyclohexylcarbodiimide-hydroxybenzotriazole coupling.

A mild procedure for preparing protected peptide hydrazides directly from the corresponding carboxylic acids and equivalent amounts of hydrazine, N-hydroxybenzotriazole and dicyclohexylcarbodiimide is described. Side reactions frequently encountered in hydrazinolysis are thus totally avoided. The process is especially useful for the preparation of aspartic acid and glutamic acid containing peptide hydrazides. No racemization of the amino acid residue was observed.