Synthesis of Ring-A-Substituted Tryptophan by a Palladium-Catalyzed Heteroamiulation Reaction

Coupling of substituted o-iodoanilines with methyl (S)2-N-,N-di-tert-butoxycarbonyl-5-oxo-pentanoate, derived from glutamic acid, in DMF in the presence of palladium acetate and DABCO provides substituted tryptophans in good to excellent yields.