Concise synthesis of 2,3-disubstituted quinoline derivatives via ruthenium-catalyzed three-component deaminative coupling reaction of anilines, aldehydes and amines.

ABSTRACT

The Ru-H complex (PCy3)2(CO)RuHCl (1) was found to be a highly effective catalyst for the three-component deaminative coupling reaction of anilines with aldehydes and allylamines to form 2,3-disubstituted quinoline products. The analogous coupling reaction of anilines with aldehydes and cyclic enamines led to the selective formation of the tricyclic quinoline derivatives. The reaction profile study showed that the imine is initially formed from the dehydrative coupling of aniline and aldehyde, and it undergoes the deaminative coupling and annulation reaction with amine substrate to form the quinoline product. The catalytic coupling method provides a step-efficient synthesis of 2,3-disubstituted quinoline derivatives without employing any reactive reagents or forming wasteful byproducts.