Selective access to fused tetrahydroquinolines via a copper-catalysed oxidative three-component annulation reaction†
Via a copper-catalyzed three-component annulation reaction, we herein report a new method for the direct and syn-selective construction of cyclic ether-fused tetrahydroquinolines from readily available secondary anilines, saturated five or six-membered cyclic ethers, and paraformaldehyde. The synthesis features operational simplicity, excellent step and atom efficiency, good functionality and substrate compatibility. In comparison with the reported synthetic protocols capable of synthesizing N-alkyl fused tetrahydroquinolines, this newly developed chemistry allows access to both N-alkyl and N-aryl products. The current work complements the preparation of fused tetrahydroquinolines.