Transition-Metal-Free Radical C(sp3)-C(sp2) and C(sp3)-C(sp3) Coupling Enabled by 2-Azaallyls as Super-Electron-Donors and Coupling-Partners
The past decade has witnessed the rapid development of radical generation strategies and their applications in C-C bond-forming reactions. Most of these processes require initiators, transition metal catalysts, or organometallic reagents. Herein, we report the discovery of a simple organic system (2-azaallyl anions) that enables radical coupling reactions under transition-metal-free conditions. Deprotonation of N-benzyl ketimines generates semistabilized 2-azaallyl anions that behave as super-electron-donors (SEDs) and reduce aryl iodides and alkyl halides to aryl and alkyl radicals. The SET process converts the 2-azaallyl anions into persistent 2-azaallyl radicals, which capture the aryl and alkyl radicals to form C-C bonds. The radical coupling of aryl and alkyl radicals with 2-azaallyl radicals makes possible the synthesis of functionalized amine derivatives without the use of exogenous radical initiators or transition metal catalysts. Radical clock studies and 2-azaallyl anion coupling studies provide mechanistic insight for this unique reactivity.
Li, Minyan,Berritt, Simon,Matuszewski, Lucas,Deng, Guogang,Pascual-Escudero, Ana,Panetti, Grace B.,Poznik, Michal,Yang, Xiaodong,Chruma, Jason J.,Walsh, Patrick J.
Synthesis of an elusive, stable 2-azaallyl radical guided by electrochemical and reactivity studies of 2-azaallyl anions
The super electron donor (SED) ability of 2-azaallyl anions has recently been discovered and applied to diverse reactivity, including transition metal-free cross-coupling and dehydrogenative cross-coupling processes. Surprisingly, the redox properties of
Panetti, Grace B.,Carroll, Patrick J.,Gau, Michael R.,Manor, Brian C.,Schelter, Eric J.,Walsh, Patrick J.
2-Azaallyl Anions as Light-Tunable Super-Electron-Donors: Coupling with Aryl Fluorides, Chlorides, and Bromides
Herein, we present 2-azaallyl anions as colored super-electron-donors capable of reducing a collection of aryl halides via a single electron transfer and coupling with the corresponding radicals to forge new C?C bonds. This offers a robust approach for th
Wang, Qianmei,Poznik, Michal,Li, Minyan,Walsh, Patrick J.,Chruma, Jason J.
p. 2854 - 2868
(2018/08/17)
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