Formal Regiocontrolled Hydroboration of Unbiased Internal Alkynes via Borylation/Allylic Alkylation of Terminal Alkynes

In accessing trisubstituted vinyl boronates from terminal alkynes, a propargyl directing (2-pyridyl)sulfonyl group allows terminal alkynes to undergo Cu-catalyzed B₂(pin)₂-borylation and subsequent Cu-catalyzed allylic alkylation with Grignard reagents without affecting the pinacolboronate moiety, thereby formally enabling a highly stereo- and regiocontrolled access to hydroboration products of unbiased dialkyl internal alkynes.