Transition Metal‐Free Synthesis of α‐Aminophosphine Oxides through C(sp3)−P Coupling of 2‐Azaallyls.

Radical reactions have been widely applied in C−P bond‐forming strategies. Most of these strategies require initiators, transition metal catalysts, or organometallic reagents. Herein, a transition metal‐free C(sp3)−P bond formation to prepare α‐aminophosphine oxides via deprotonative radical coupling processes of 2‐azaallyls with chlorodiphenylphosphine oxides was presented. Deprotonation of N‐benzyl imines may generate super‐electron‐donor (SED) 2‐azaallyl anions that reduced chlorodiphenylphosphine oxides to phosphine oxide radicals. Single‐electron transfer (SET) process transformed the 2‐azaallyl anions into 2‐azaallyl radicals, which may couple with phosphine oxide radicals to construct C−P bonds. The deprotonative radical coupling approach enables the synthesis of α‐aminophosphine oxides bearing various functional groups under mild conditions and without precious transition metal catalysts or oxidants. [ABSTRACT FROM AUTHOR]