Benzylic C(sp<sup>3</sup>)–H/C(sp<sup>3</sup>)–H Coupling with 2-Azaallyl Anions through Single-Electron Transfer and 1,5-Hydrogen Atom Transfer
Dongxiang Liu, Bijun Wang, Cuirong Qin, Haoqing Tang, Hui Li, Liang Li, Yonggang Jiang, Xiaodong Yang
Abstract
Herein is reported a novel transition-metal-free intermolecular C(sp 3 )–H/C(sp 3 )–H coupling of N-tert -butyl arylamides with N -benzyl imines through single-electron transfer (SET) and 1,5-hydrogen atom transfer (1,5-HAT) strategies. 2-Azaallyl anions as super-electron-donors (SEDs) undergo SET with N-tert -butyl arylamides to generate 2-azaallyl radicals and amidyl radicals. The amidyl radical undergoes a 1,5-HAT process to form a C-centered radical, which is subsequently coupled to a 2-azaallyl radical to generate new C–C bonds. This method avoids the use of transition metals and photoredox catalysts with good functional group tolerance and yields (29 examples, 87% yield). Radical clock and radical trapping experiments provide significant evidence for the 1,5-HAT process of amidyl radicals.