p -TSA·H 2 O catalyzed metal-free and environmentally benign synthesis of 4-aryl quinolines from arylamine, arylacetylene, and dimethyl sulfoxide.

An environmentally benign and metal-free synthesis of 4-aryl quinolines is reported by employing readily available arylamine, arylacetylene, and DMSO in the presence of 20 mol% p -TSA·H 2 O. In the present protocol, the solvent DMSO serves as a reactant cum solvent for providing the C2 carbon atom of the quinoline skeleton. Notably, the reaction proceeds effectively and efficiently without the involvement of any metal catalyst, ligand, and co-catalyst as additives and inert atmospheric reaction conditions. This method provides high atom economy and good yields, and two C - C and one C - N bonds are formed in a single step through a three-component reaction.