Tandem Electrochemical Oxidative Azidation/Heterocyclization of Tryptophan‐Containing Peptides under Buffer Conditions

Abstract As the aromatic tryptophan (Trp) side chain plays a pivotal role in influencing the structure and function of peptides and proteins, it has become an attractive target for the late‐stage modification of these important biomolecules. Herein, we report an electrochemical approach for late‐stage functionalization of peptides containing a Trp side chain through manganese‐catalyzed tandem radical azidation/heterocyclization. This electrochemical oxidative strategy provides access to azide‐substituted tetrazolo[1,5‐ a ]indole‐containing peptides with broad functional group tolerance, high site selectivity, and good yields of products (up to 87 %) under mild buffer conditions. Moreover, the modified Trp‐containing peptides bearing an azide functionality are promising building blocks, paving the way for the construction of various derivatives, such as “click” chemistry products.