Photocatalytic C(sp3)-H gem-Difluoroallylation and Alkylation with Alkenes via a Base-Assisted Formal 1,2-Hydrogen Atom Transfer of Amidyl Radicals

Compared to well-established 1,5-HAT of N-centered radicals, the synthetic applications of 1,2-HAT process were scarce due to the high barrier and constrained three-membered transition state. Here, we have developed a novel C(sp(3))-H gem-difluoroallylation via a base assisted formal 1,2-HAT of amidyl radicals with the reductive quenching cycle of photocatalyst. This transformation enables the efficient formation of alpha-aminoalkyl radicals via 1,2-HAT and showcases good functional group tolerance. Our preliminary mechanistic experiments, along with Density Functional Theory (DFT) calculations demonstrate the feasibility of 1,2-HAT of amidyl radicals, especially when assisted by a base. Furthermore, our method also succeeds in the Giese addition of electron-deficient alkenes as well as styrene.