Light induced synthesis of symmetrical and unsymmetrical dihydropyridines in ethyl lactate-water under tunable conditions

A highly efficient environment-friendly one-pot green methodology has been developed for the synthesis of symmetrical and unsymmetrical 1,4-dihydropyridines and polyhydroquinolines following the multicomponent Hantzsch synthesis under visible light irradiation in ethyl-L-lactate-water solution at room temperature. The present methodology offers several advantages such as simple procedure, greener condition, excellent yields and short reaction time sans any catalyst, support or promoter. The developed protocol has been materialized with the involvement of a household compact tungsten lamp as the visible light source, and the manifested high selectivity of the reaction performed in ethyl lactate-water solvent mixture under tunable conditions. The Ca2+ channel blocker nitrendipine and nemadipine B were also successfully synthesized applying the developed methodology in high yields. (C) 2012 Elsevier Ltd. All rights reserved.