Stereodivergent α-Addition of Yne-allylic Esters by the <i>Z</i> / <i>E</i> -Selective Multicomponent Reaction

The precise control of complicated regioselectivity of 1,3-enynes upon an addition reaction has been a long-standing challenge in synthetic chemistry, even more pronounced when simultaneously striving to achieve both <i>Z</i> and <i>E</i> selectivity. Herein, a unique copper-catalyzed stereodivergent α-addition of yne-allylic esters for the <i>Z</i>/<i>E</i>-selective multicomponent reaction is disclosed. The esters' leaving ability and the steric hindrance effect of intermediates synergistically controlled the regioselectivity and stereoselectivity for synthesizing both <i>Z</i>- and <i>E</i>-dienylamidines in up to 94% yield, with 67 examples involving the formation of an uncommon vinyl ketenimine intermediate and a vinyl alkylidene ketenimine intermediate, respectively.