Visible-light-activated C–C and C–N bond formation in the synthesis of imidazo[1,2-a]pyridines and imidazo[2,1-b]thiazoles under catalyst and solvent-free conditions

The formation of a 3-aminoimidazo-fused heterocyclic compound and its derivatives through a multicomponent one-pot reaction, activated by visible light, is reported. The noticeable feature of this protocol is the utilization of a universally available energy source to activate the reaction. The reported methodology is the first protocol that represents the implementation of visible light for this Ugi-type synthesis from 2-aminoheterocycles, aldehydes, and isocyanides as well as offers the advantages of improved selectivity, outstanding yields, solvent and catalyst-free conditions, environmental sustainability and convenient access to starting materials.