Visible Light-Mediated Multicomponent Synthesis of Spirooxindole-Linked Fused Pyrans: An Eco-Friendly One-Pot Strategy

A green and efficient method for the preparation of spirooxindole-linked fused pyrans has been developed utilizing a catalyst-free visible-light-driven one-pot multicomponent reaction strategy. The reaction was performed in a water and ethanol mixture, using the combination of isatin, malononitrile, and cyclic 1,3-dicarbonyls such as 4-hydroxy-1-methyl-2(1H)-quinolone, 4-hydroxycoumarin, 4-hydroxythiocoumarin, or barbituric acid derivatives. This catalyst-free, environmentally friendly, visible-light-driven, and room temperature method is a valuable addition to the synthetic toolbox for constructing complex heterocyclic scaffolds under one-pot conditions. It holds promise for future applications in medicinal chemistry and drug discovery. We report a visible-light-mediated, catalyst-free multicomponent reaction for the efficient synthesis of spirooxindole-linked fused pyrans. The reaction involves isatin, malononitrile or its derivatives, and various cyclic 1,3-dicarbonyl compounds such as 4-hydroxy-1-methyl-2(1H)-quinolone, 4-hydroxycoumarin, 4-hydroxythiocoumarin, or barbituric acid derivatives, yielding the corresponding spirooxindole-linked fused pyrans. Key features of this method include the use of a water-ethanol solvent mixture, visible light as the energy source, and catalyst-free conditions. image