1 research outputs found
Transition-Metal-Free Radical C(sp<sup>3</sup>)–C(sp<sup>2</sup>) and C(sp<sup>3</sup>)–C(sp<sup>3</sup>) 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 <i>N</i>-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