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.

Diazines and Triazines as Building Blocks in Ligands for Metal-Mediated Catalytic Transformations

“…If silanes are used as reaction partners, the method used for precatalyst activation was found to determine the reaction outcome: in the absence of an external base, dehydrocoupling is observed, while using LiO t Bu as activator stirs the reactivity toward hydrosilylation . Derivatives of 60 with different variations of the R substituents on the heteroaromatic ring have been used for catalytic hydroboration and hydrosilyation of alkynes and olefins, or in the silylation of silanols …”