A mild and eco-friendly visible-light-mediated regioselective C–H alkoxycarbonylation of imidazo­[1,2-a]­pyridine heterocycles using rose bengal as a photoredox catalyst at room temperature has been developed. Biologically important alkoxycarboxylated imidazo­[1,2-a]­pyridines at the C-3 position as well as coumarins and quinoxalin-2­(1H)-ones have been prepared. The present approach has the advantage of having a user- and eco-friendly catalyst, a carbonyl source, as well as extremely mild conditions for direct and regioselective C–H alkoxycarbonylation mediated by visible light as a green energy source.

A mild and efficient synergistic approach for decarboxylative aroylation of 2-aryl-pyrido[1,2-a]pyrimidin-4ones having intrinsic directing group has been developed by merging of palladium catalysis and photoredox catalysis at [a] R.