Copper-Catalyzed Asymmetric Alkynylation of sp 2 Allenic C–H Bonds for the Synthesis of Skipped Diynes

Herein, we established a copper-catalyzed asymmetric alkynylation of the sp 2 C–H bond of silylallenes, which was presented as an efficient method for the synthesis of enantioenriched skipped diynes with excellent enantioselectivity. The reaction was initiated by hydrogen atom abstraction of sp 2 allenic C–H bonds, in which the resonance forms of allenic and propargylic radicals were chemo- and en…