Copper(II)-Catalyzed Aerobic Oxidative Desulfitative 6π Electrocyclization: Efficient Synthesis of Diverse 4-Aminoquinolines.

The C−C bond formation via C−S bond activation (disclosed in 2000) has received increasing attention. However, stoichiometric amounts of exogenous thiophilic reagents are generally required as thiolate scavengers. Herein, a new model for the synthesis of 4-aminoquinolines, the copper(II)-catalyzed aerobic oxidative desulfitative 6π cyclization of the readily available N-arylimino ketene N,S-acetals is described. The reaction can proceed efficiently under mild conditions without any exogeneous thiolate scavengers (due to the formation of disulfide as the by-product) to afford diverse 4-aminoquinolines, a privileged structure motif displaying antimalarial activity, with a wide range of functional groups at the C-2 to C-8 positions. [ABSTRACT FROM AUTHOR]