Environment-sensitive fluorescent tryptophan analogues via indole C-2 alkenylation reactions

Abstract

A modular synthetic strategy for the preparation of intrinsically fluorescent unnatural α-amino acids by C-2 oxidation and alkenylation of a tryptophan-derived tetrahydro-β-carboline is described. This approach yielded a novel tryptophan–coumarin hybrid with strong environmental sensitivity and compatibility with near-infrared two-photon excitation.