Synthesis and biological evaluation of 5-chalcogenyl-benzo[h]quinolines via photocyclization of arylethynylpyridine derivatives

A new and efficient method for the synthesis of 6-organyl-5-(arylselanyl)benzo[h]quinolines via visible light-promoted intramolecular ortho-cyclization of 2-aryl-3-(organylethynyl)pyridines has been achieved. The reaction was promoted by radical organochalcogen species generated in situ using diorganyl dichalcogenides, indium chloride as a green Lewis acid and acetonitrile under an argon atmosphere. The protocol showed high regioselectivity and allowed the synthesis of eleven benzo[h]quinoline derivatives in low to good yields. Also, compound 5a demonstrated in vitro antioxidant activity as well as in silico appropriate pharmacodynamic and pharmacokinetic profiles, suggesting that this compound may have promising therapeutic potential.