Facile syntheses of tetrahydroquinolines and 1,2-dihydroquinolines via vinylogous cascade hydride transfer/cyclization

Abstract

Medicinally significant 3-monosubstituted tetrahydroquinolines and 1,2-dihydroquinolines were controllably constructed via redox-neutral vinylogous cascade condensation/[1,5]-hydride transfer/cyclization in EtOH from readily available starting materials with alkenyl and coumarin moieties being introduced facilely, which have the features of green solvent, novel hydride acceptor, metal-free conditions, controllable syntheses of hydroquinoline derivatives and with water as the only by-product. In addition, the electrophilicity and nucleophilicity of α,α-dicyanoalkenes have been consecutively employed as hydride acceptors and γ-exclusive nucleophiles.