Brønsted acid-catalyzed metal- and solvent-free quinoline synthesis from N-alkyl anilines and alkynes or alkenes

Abstract

Brønsted acid-catalyzed cyclization reactions of N-alkyl anilines with alkynes or alkenes in the presence of oxygen gas as an oxidant under metal- and solvent-free conditions are described. Various quinoline derivatives are obtained in satisfactory to excellent yields. Different groups, such as methyl, fluoro, chloro, bromo, methoxy, and ester linked on benzene rings, are tolerated under optimized reaction conditions.