Intermolecular chirality transfer from silicon to carbon: Interrogation of the two-silicon cycle for Pd-catalyzed hydrosilylation by stereoisotopochemical crossover

A two-silicon cycle for the highly efficient intermolecular chirality transfer from silicon to carbon (98-99% ct) in the palladium-catalyzed hydrosilylation of norbornenes emerges from an investigation involving catalytic crossover experiments with isotopically labeled silicon-stereogenic silanes. A key outcome of these experiments, which are supported by product-distribution modeling, is the conclusion that the chirality transfer arises from thermodynamically controlled reversible silapalladation of the alkene rather than from kinetic control during irreversible -bond metathesis of the resulting -silyl -alkyl palladium complex with chiral silane.