Visible Light Mediated Synthesis of 3‐Indolmethyl Chromones via the Cyclization of o‐Hydroxyaryl Enaminones with 3‐Indoleacetic Acids Catalyzed by Graphitic Carbon Nitride Adorned with Copper Nanoparticles

Abstract

Copper nanoparticles (Cu2O NPs) supported on graphitic carbon nitride (g‐C3N4) have been introduced as an effective heterogenous catalyst for the synthesis of 3‐indolmethyl chromones (3a‐q) under visible light conditions via the cyclization of o‐hydroxyaryl enaminones with 3‐indoleacetic acids. The catalyst was thoroughly characterized using various techniques such as FT‐IR, PXRD, XPS, FE‐SEM, EDX, TEM, and HR‐TEM analysis. The optimized reaction conditions enabled the high yield production of a wide range of 3‐indolmethyl chromones in a short timespan at room temperature under visible light and method was successfully applied to the gram‐scale synthesis. Importantly, the catalyst could be reused for up to five cycles without significant decrease in its activity. This approach aligns with eco‐friendly principles, demonstrating favorable green chemistry metrics for compound 3a, including process mass intensity (7.83), environmental impact factor (6.83), atom economy (67.56 %), reaction mass efficiency (60.76 %), chemical yield (92.37 %), mass intensity (1.64), mass productivity (60.97 %), carbon efficiency (69.15 %) and optimum efficiency (89.93 %).