Co‐catalyzed Selective syn‐Hydrosilylation of Internal Alkynes

Abstract Vinylsilanes are highly appealing and convenient chemical derivatives, as evidenced by the increasing number of synthetic transformations utilizing this class of compounds. Herein, a new comprehensive cobalt‐catalyzed procedure has been developed enabling selective hydrosilylation of internal aryl‐, alkyl‐, and silylalkynes. Cobalt complexes bearing triazine‐based PNP pincer‐type ligands provide exclusive syn ‐addition of primary as well as secondary silanes to C≡C bonds. As a result, ( E )‐silylalkenes and vicinal disilylalkenes were effectively obtained with excellent stereoselectivity and regioselectivity. Unlike several TM‐catalyzed procedures, no external additives were required since hydrosilanes act as both substrates and activators.