Quinoline Syntheses via Copper-Catalyzed Domino Reaction of 2-Halogenated Benzaldehydes and Enaminones

Abstract

Quinolines showing broad range of biological activities were obtained from enaminones and 2-bromo- or 2-iodobenzaldehyde via copper-catalyzed tandem reaction. The domino processes consisted of aldol reaction, C(aryl)-N bond formation and elimination. The electronic effect of aldehydes and drying agent displayed a huge impact on product yield. Both 2-bromo- and 2-iodobenzaldehydes provided a library of quinolines from cyclic and acyclic enaminones in good yields. Diethyl-2-(2- bromobenzylidine)malonate was introduced to the reaction instead of aldehyde as a better coupling partner of non-active enaminones.