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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]

A unique C(sp 3 )-H/C(sp 3 )-H dehydrocoupling of N -benzylimines with saturated heterocycles is described. Using super electron donor (SED) 2-azaallyl anions and aryl iodides as electron acceptors, single-electron-transfer (SET) generates an aryl radical. Hydrogen atom transfer (HAT) from saturated heterocycles or toluenes to the aryl radical generates alkyl radicals or benzylic radicals, respectively. The newly formed alkyl radicals and benzylic radicals couple with the 2-azaallyl radicals with formation of new C-C bonds. Experimental evidence supports the key hydrogen-abstraction by the aryl radical, which determines the chemoselectivity of the radical-radical coupling reaction. It is noteworthy that this procedure avoids the use of traditional strong oxidants and transition metals., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Benzofurans are among the most popular structural units in bioactive natural products, however, the synthesis of such structures by radical cyclization cascade reactions is rare. Herein, we report a mild and broadly applicable method for the construction of complex benzofurylethylamine derivatives through a unique radical cyclization cascade mechanism. Single-electron transfer (SET) from 2-azaallyl anions to 2-iodo aryl allenyl ethers initiates a radical cyclization that is followed by intermolecular radical-radical coupling. This expedient approach enables the synthesis of a range of polycyclic benzofurans that would otherwise be difficult to prepare., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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.