Palladium-catalyzed intermolecular aerobic oxidative cyclization of 2-ethynylanilines with isocyanides: regioselective synthesis of 4-halo-2-aminoquinolines.

A robust and regioselective palladium-catalyzed intermolecular aerobic oxidative cyclization of 2-ethynylanilines with isocyanides to the synthesis of 4-halo-2-aminoquinolines is reported herein. The procedure constructs various 4-halo-2-aminoquinolines with moderate to excellent yields (47-94%) and broad substrates scope. Furthermore, this process can be easily extended to synthesis of various 6H-indolo[2,3-b]quinolines via an intramolecular Buchwald-Hartwig cross-coupling reaction in two-step one-pot manner.