Visible light photocatalysis of radical anion hetero-Diels–Alder cycloadditions

We have discovered a photocatalytic intramolecular hetero-Diels–Alder reaction of tethered bis(enones). This transformation involves the intermediacy of an enone radical anion and constitutes the formal coupling of an electron-deficient heterodiene with an electronically mismatched enone dienophile. The diastereoselectivity and regioselectivity of the process are high, and the dihydropyran products are amenable to a variety of synthetically useful transformations.