Synthesis of Polysubstituted Quinolines via Transition-Metal-Free Oxidative Cycloisomerization of o-Cinnamylanilines

An efficient synthesis of 2-aryl 4-substituted quinolines from stable and readily available o-cinnamylanilines, prepared from anilines and cinnamylalcohols, has been developed. The reaction occurred via a regioselective 6-endo-trig intramolecular oxidative cyclization using KO(t)Bu as a mediator and DMSO as an oxidant at rt. The reaction showed a broad substrate scope with good to excellent yields.