An Unusual Perpendicular Metallacycle Intermediate is the Origin of Branch Selectivity in the Rh(II)-Catalyzed C–H Alkylation of Aryl Sulfonamides with Vinylsilanes

The rhodium(II)-catalyzed, branch-selective C–H alkylation of aryl sulfonamides with vinylsilanes was recently developed by our group, and the unique reactivity and selectivity of the reaction was extensively studied using density functional theory (DFT) calculations. A detailed computational study of the experimentally confirmed reaction intermediates permitted us to understand the nature of dirhodium complexes, and the findings indicated that a strained perpendicular metallacycle is formed, which disfavors the development of linear-selective migratory insertion transition states.