Visible-light promoted regioselective amination and alkylation of remote C(sp(3))-H bonds.

The C-N cross coupling reaction has always been a fundamental task in organic synthesis. However, the direct use of N-H group of aryl amines to generate N-centered radicals which would couple with alkyl radicals to construct C-N bonds is still rare. Here we report a visible light-promoted C-N radical cross coupling for regioselective amination of remote C(sp3)-H bonds. Under visible light irradiation, the N-H groups of aryl amines are converted to N-centered radicals, and are then trapped by alkyl radicals, which are generated from Hofmann-Loffler-Freytag (HLF) type 1,5-hydrogen atom transfer (1,5-HAT). With the same strategy, the regioselective C(sp3)-C(sp3) cross coupling is also realized by using alkyl Hantzsch esters (or nitrile) as radical alkylation reagents. Notably, the α-C(sp3)-H of tertiary amines can be directly alkylated to form the C(sp3)-C(sp3) bonds via C(sp3)-H − C(sp3)-H cross coupling through the same photoredox pathway. C-N bond forming is an established strategy to form amines, which are quintessential in chemical synthesis and in nature. Here, the authors report three classes of photoredox reactions, involving C(sp3)-N coupling between N-centered radicals and alkyl radicals and C(sp3)- C(sp3) coupling via C(sp3)-H alkylation.