Visible light-driven photocatalyst-free cascade synthesis of functionalized benzopyrans as inhibitors of Chikungunya nsPs and Zika NS2B-NS3

Herein, we report a visible light-mediated, metal- and photocatalyst-free, green and sustainable synthesis of biologically relevant functionalized benzopyrans by a one-pot, pseudo-multicomponent reaction at room temperature. The notable features of the present protocol include a green and renewable energy source, high yields, easy isolation of the products without performing column chromatography, metal- and photocatalyst-free conditions, room-temperature synthesis, broad substrate scope, environmental friendliness and gram-scale synthesis of the products. In the present study, the benzopyrans are also subjected to molecular docking, which revealed that some benzopyrans are promising potential inhibitors of key nsPs in both Chikungunya and Zika viruses. Several benzopyrans display appreciable binding affinities for nsP1, nsP2, and nsP4 of Chikungunya virus and the NS2B-NS3 protease of Zika virus.