Unusually Large Primary ²H/¹H Kinetic Isotope Effects Accompanying a syn-β-H Elimination Reaction in a σ-Alkyl -- Palladium Complex.

Syn-β-Hydride elimination of α-bound alkyl, alkoxy, or alky- lamine ligands is a fundamental process in organometallic catalysis and the stereochemistry of such processes can have important mechanistic consequences. Indeed, the restrictions placed on C-C rotation by use of a cyclic substrate and the syn nature of the β-hydride elimination that develops from an agostic interaction are essential components of the asymmetric Heck reaction. Syn-β-H elimination from Pd-σ-alkyl complexes has resulted in rare cases of anti-&beta-H elimination.