Visible-Light-Promoted Intramolecular C-O Bond Formation via C sp 3 - H Functionalization: A Straightforward Synthetic Route to Biorelevant Dihydrofuro[3,2- c ]chromenone Derivatives.

A photochemical method for the synthesis of functionalized dihydrofuro[3,2- c ]chromenones via intramolecular C _{sp ³} -H cross -dehydrogenative oxygenation within a warfarin framework has been unearthed. Advantages of this protocol include abundant sunlight or low-energy visible light as the energy source, mild reaction conditions, and avoidance of metal catalysts.