Regioselective Access to α‑Vinylsilanes and α‑Vinylgermanes by Cobalt-Catalyzed Migratory Hydrofunctionalization of 2‑Alkynes

While migratory functionalization of alkynes has been recognized as a unique way to access allylic functionalities via π-allyl metal intermediates, hydrofunctionalization of 2-alkynes to afford α-functional olefins has been unexplored. We describe herein the use of a cobalt hydride based system for regioselective migratory hydrofunctionalization of 2-alkynes to furnish α-vinylsilanes and α-vinylgermanes by a mechanistic understanding of the cobalt hydride species on alkyne π-bond migration. The key mechanism of alkyne π-bond migration by [bis­(dicyclohexylphosphino)­ethane]­cobalt hydride is strongly supported by both experimental and computational studies, and the role of each reaction component, such as alkynes and silanes, is elucidated to rationalize the unique α-vinyl selectivity.

尽管炔烃的迁移官能化（migratory functionalization）已被公认为通过π-烯丙基金属中间体（π-allyl metal intermediates）制备烯丙基官能团（allylic functionalities）化合物的独特途径，但针对2-炔烃的氢官能化（hydrofunctionalization）以合成α-官能化烯烃（α-functional olefins）的研究仍未被探索。
本文报道了一种基于氢化钴（cobalt hydride）的催化体系，通过对炔烃π键迁移过程中氢化钴物种的机理认知，实现了2-炔烃的区域选择性迁移氢官能化（regioselective migratory hydrofunctionalization），从而得到α-乙烯基硅烷（α-vinylsilanes）与α-乙烯基锗烷（α-vinylgermanes）。
由[双(二环己基膦基)乙烷（bis(dicyclohexylphosphino)ethane）]氢化钴介导的炔烃π键迁移关键机理，得到了实验与计算研究的共同佐证；本研究同时阐明了炔烃、硅烷等各反应组分的作用，以此合理化该独特的α-乙烯基选择性（α-vinyl selectivity）。