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.