Visible-Light-Promoted Intramolecular C–O Bond Formation via Csp3–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 Csp3–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.