The backbone N-(4-azidobutyl) linker for the preparation of peptide chimera

A robust synthetic strategy for the introduction of the N-(4-azidobutyl) linker into peptides using standard SPPS techniques is described. Based on the example of Cilengitide it is shown that the N-(4-azidobutyl) group exerts similar conformational restraints as a backbone N-Me group and allows conjugation of a desired molecule either via click chemistry or - after azide reduction - via acylation or reductive alkylation.