Two Reactivities for the Price of One Cycle: Sulfonamides as Dual Photoinduced Electron Transfer/Hydrogen Atom Transfer Catalysts

Cyclic biaryl sulfonamides (BASNs) have emerged as a versatile and synthetically accessible class of reductive organophotocatalysts for photoinduced electron transfer (PET) reactions. Following PET engagement of a reductively labile substrate, BASN– transforms into a nitrogen-centered radical. Leveraging this intermediate to activate C–H bonds of a second substrate via hydrogen atom transfer (HAT) would culminate in two reactivities for the price of one catalytic cycle. The bifunctional PET-HAT ability of BASN was demonstrated through the reductive activation of gem-difluoroalkenes and electron-deficient arenes together with selective HAT activation of α-heteroatom and allylic C(sp3)-H under visible-light irradiation. Radical ions/radicals generated from the PET- and HAT-activated substrates converge to form a single product, resulting in a high atom economy.