Rhodium-Catalyzed Regioselective C7_Ar-Functionalization of Tryptophan with Quinones and its Late Stage Peptide Exemplification

Pivaloyl-directed Rh(III)-catalyzed regioselective C7(Ar)-H functionalization of protected tryptophans were accomplished with 1,4-benzoquinones, furnishing a series of quinone-appended tryptophan-based unnatural amino acids in high yields. Further, the late stage functionalization on tryptophan-containing dipeptides was achieved with 1,4-benzoquinones in moderate reactivity.