Copper‐Catalyzed Asymmetric Cyanation of Propargylic Radicals Derived from Silyl‐Substituted Allenes and Alkynes

Here, we report an efficient method to synthesize enantiomerically enriched propargyl nitriles via copper‐catalyzed asymmetric cyanation of propargylic radicals, which are generated from silyl‐substituted allenes or alkynes. These reactions proceeded through a highly site‐selective hydrogen atom abstraction (HAA) with Cu(II)‐bound nitrogen‐centered radicals (NCRs). Notably, silyl‐ substituted allenes demonstrate exceptional allenic sp2 C‐H bond activation selectivity, outcompeting alternative reactive sp3 C‐H bonds (benzylic, allylic, and heteroatom‐adjacent) in HAA processes. This chemo‐selectivity profile enables precise enantiocontrol and site‐specific functionalization of complex molecular architectures.