Tryptophan-specific peptide modification through metal-free photoinduced N-H alkylation employing N-aryl glycines

Tryptophan(Trp)carries a unique heteroaromatic indole side chain and plays a critical role in peptide or protein modification.Herein,we have reported a metal-free photoinduced N-H alkylation strategy using N-aryl glycines for specific modification of tryptophan-containing peptides.The robustness of our approach is demonstrated by its wide substrate scope,excellent isolated yields,as well as almost unobservable side effects.Using this highly efficiently metal-free condition,alkylated Trp-containing peptides can be smoothly assembled.This study provides a reliable and practical tool for the chemo-selective modification of various tryptophan containing oligopeptides.