Cobalt‐Catalyzed Regiodivergent Double Hydrosilylation of Arylacetylenes

Abstract Double hydrosilylation of alkynes represents a straightforward method to synthesize bis(silane)s, yet it is challenging if α‐substituted vinylsilanes act as the intermediates. Here, a cobalt‐catalyzed regiodivergent double hydrosilylation of arylacetylenes is reported for the first time involving this challenge, accessing both vicinal and geminal bis(silane)s with exclusive regioselectivity. Various novel bis(silane)s containing Si−H bonds can be easily obtained. The gram‐scale reactions could be performed smoothly. Preliminarily mechanistic studies demonstrated that the reactions were initiated by cobalt‐catalyzed α‐hydrosilylation of alkynes, followed by cobalt‐catalyzed β‐hydrosilylation of the α‐vinylsilanes to deliver vicinal bis(silane)s, or hydride‐catalyzed α‐hydrosilylation to give geminal ones. Notably, these bis(silane)s can be used for the synthesis of high‐refractive‐index polymers ( n d up to 1.83), demonstrating great potential utility in optical materials.