Diverse radical transformations of allenic C(sp)–C(sp2) and C(sp3)–C(sp2) bonds enabled by silyl substitution

While the oxidative cleavage of olefins is well established, the radical-mediated, chemo- and regioselective cleavages of allene C(sp)–C(sp2) and C(sp3)–C(sp2) bonds remain unresolved challenges in synthetic chemistry. These challenges primarily stem from the high reactivity of the unique twisted orthogonal π-systems and the regioselectivity issues associated with adjacent C = C double bonds. Herein, we present base metal-catalyzed cleavage of allenic C(sp)–C(sp2) double bonds and C(sp3)–C(sp2) single bonds utilizing air as an oxidant. These transformations, initiated by hydrogen atom abstraction (HAA) from the allenic C(sp2)–H bonds, lead to the formation of a diverse range of remotely functionalized ketones, alkylated heteroaryls, alkylated nitriles, and deuterated products, all with remarkable site selectivity. In this strategy, the α-silyl effect plays a key role in activating allenic C(sp2)–H bond thus initiating the HAA from allenes and achieving the desired regioselectivity. While the oxidative cleavage of olefins is well established, the radical-mediated, chemo- and regioselective cleavages of allene C(sp)–C(sp2) and C(sp3)– C(sp2) bonds remain unresolved challenges in synthetic chemistry. Herein, the authors present base metal-catalyzed cleavage of allenic C(sp)–C(sp2) double bonds and C(sp3)–C(sp2) single bonds utilizing air as an oxidant.