Photocatalytic C H alkylation of coumarins mediated by triphenylphosphine and sodium iodide

Metal- and oxidant-free photocatalytic C H alkylation of coumarins is developed in the presence of triphenylphosphine and sodium iodide under blue LEDs irradiation by using the easily available alkyl N -hydroxyphthalimide esters as the alkylation reagents. The metal- and oxidant-free decarboxylative C H coupling protocol provides various 3-alkylated coumarins, as well as quinoxalinones, in satisfactory yields with excellent C-3 regioselectivity.