Studies on polypeptides VI: Synthesis of protected hexa‐ and octa‐peptide hydrazides related to the N‐terminal part of bovine pancreatic ribonuclease a using the solid‐phase method

Merrifield's solid‐phase method was applied to the synthesis of all‐L‐ t ‐butoxycarbonylthreonylalanylalanylalanyl‐N ϵ ‐benzyloxycarbonyllysylphenylalanine hydrazide and all‐L‐ N α , N ϵ ‐di‐ t ‐butoxycarbonyllysyl‐γ‐ t ‐butylglutamylthreonylalanylalanylalanyl‐ N ϵ ‐benzyloxycarbonyllysylphenylalanine hydrazide. Cleavage from the solid support with a solution of hydrazine hydrate in dimethylformamide and additional purification gave homogeneous products in high overall yields. Conventional syntheses of these compounds led to identical products.