Cobalt-Catalyzed Regio- and Stereoselective Hydrosilylation of Alk-2-ynes with Tertiary Silanes
Hongfang Li, Chengbo Yang, Dongyang Wang, Liang Deng
Abstract
Selectivity control in the addition reactions of internal alkynes that bear two similar substituents presents a big challenge in modern organic synthesis. Herein we report that β-( E )-selective hydrosilylation of alk-2-ynes with tertiary silanes can be achieved by using Co 2 (CO) 8 as the catalyst. Under the catalytic reaction conditions, a wide range of alk-2-ynes can be converted into vinylsilanes with the β-( E ) isomers as the major or sole hydrosilylation products. Mechanistic studies suggest that alkyne-bridged dicobalt species are the likely intermediates. Steric repulsion between substituents in alkenyl-bridged dicobalt silyl intermediates is proposed as the key factor inducing the observed regioselectivity.