Visible light-induced environment-friendly cross-dehydrogenative coupling reaction of N-heterocycles with aldehyde

The development of efficient and sustainable methods for constructing carbon-carbon bonds is a pivotal challenge in modern green chemistry. Herein, we unveil a visible-light-driven oxidative cross-dehydrogenative coupling strategy between N-heterocycles and aldehydes using rose bengal as an organophotoredox catalyst under environmentally benign reaction conditions. This innovative green approach enables the direct acylation of N-heterocycles with various aldehydes, delivering high yields under mild reaction conditions at room temperature. Mechanistic studies demonstrate a radical pathway in which visible light activates a photocatalyst (rose bengal), leading to the generation of acyl radicals through single-electron transfer (SET). These radicals subsequently react with N-heterocycles to yield acylated products. This method is highly valuable for synthesizing diverse N-heterocyclic frameworks due to its mild reaction conditions, simple operation, and broad substrate scope. This research enhances photoredox catalysis and establishes a basis for more sustainable and adaptable synthetic methods.