Camphorsulfonic Acid Catalyzed One-Pot Three-Component Reaction for the Synthesis of Fused Quinoline and Benzoquinoline Derivatives

A simple and an efficient one-pot three-component reaction of arylamines, aromatic aldehydes, and cyclic ketones was described for the synthesis of various fused quinoline, benzoquinoline, and naphthoquinoline derivatives by using camphorsulfonic acid as a catalyst. The exploitation of pregnenolone steroid for benzoquinolines and terephthalaldehyde for bis-benzoquinolines synthesis was achieved with 68-75% yields. The reactivity of arylamines and the mechanistic study for the formation of benzoquinoline was described precisely. The present protocol offers a great potential for atom-economy under mild conditions.