Direct β‑C(sp³)–H Functionalization of Aliphatic Amines to α,β-Unsaturated Imines, Aldehydes, and Chromenes

A metal-free method for direct β-C­(sp3)–H functionalization of aliphatic amine was developed. The method is based on a reaction that yields enamine directly from the corresponding aliphatic amine, which otherwise requires the aid of metallic reagent and/or external oxidant. The reaction is operationally simple, general, and highly efficient in functionalizing both cyclic and acyclic amines. Structurally diverse unsaturated imines were obtained from N-heterocycles, while acyclic amines provided 2-alkyl cinnamaldehyde and benzopyran derivatives with excellent E/Z-selectivity.