Theoretical Investigation on the Copper‐Catalyzed <i>anti</i>‐Selective 1,2‐Silylboration of Internal Alkynes

Abstract The mechanism of a copper‐catalyzed regio‐ and anti ‐selective 1,2‐silylboration of internal alkynes was theoretically studied to understand the reaction pathway and the origin of selectivity. The proposed overall reaction pathway involves the syn ‐to‐ anti isomerization via an anionic allenic transition state stabilized by the conjugation with the benzene ring. The anti ‐selectivity is determined at the borylation step and controlled by the steric effect of the silyl group introduced on the alkyne carbon. The computational results obtained in this study are highly informative for the development of new catalytic transformations involving syn / anti ‐isomerization processes.