Manganese-Catalyzed Desaturation of N-Acyl Amines and Ethers

Enamines and enol ethers are versatile synthons for chemical synthesis. While several methods have been developed to access such molecules, prefunctionalized starting materials are usually required, and direct desaturation methods remain rare. Herein, we report direct desaturation reactions of N-protected cyclic amines and cyclic ethers using a mild I(III) oxidant, PhI(OAc)(2), and an electron-deficient manganese pentafluorophenylporphyrin catalyst, Mn(TPFPP)Cl. This system displays high efficiency for alpha,beta-desaturation of various cyclic amines and ethers. Mechanistic probes suggest that the desaturation reaction occurs via an initial alpha-C-H hydroxylation pathway, which serves to protect the product from overoxidation.