Visible light-induced green synthesis of 2-amino-4H-chromenes

Green chemistry aims at developing reactions that are cheap, clean and use less energy. For that, multicomponent reactions are drawing attention, yet, actual methods involve complicated work-ups, hazardous solvents, toxic catalysts, high catalyst loads, harsh reaction conditions and tedious catalyst preparation. Here, we demonstrate that the commercially available reagent, 9-mesityl-10 methylacridinium perchlorate (Acr+-Mes ClO4−), can serve as a photocatalyst in the presence of a blue lamp light source, promoting the synthesis of 2-amino-4H-chromenes via a multicomponent reaction with low catalyst loadings. A wide range of aromatic aldehydes readily undergo condensation with malononitrile and ArOH-type structural motifs under mild conditions to afford the products in 76–95% yield within 60 min.