Unusually Large Primary 2H/H Kinetic Isotope Effects Accompanying a syn-β-H Elimination Reaction in a σ-Alkyl−Palladium Complex
- 17 February 2004
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 126 (9) , 2690-2691
- https://doi.org/10.1021/ja039349n
Abstract
The Pd−σ-alkyl complex 5, is stable in solution for long periods in the absence of base. On addition of simple amine bases, such as 1,8-bis(dimethylamino)naphthalene (7), complex 5 rapidly generates the triene 6 via a β-H elimination process whose stereochemistry is demonstrated to be syn. In contrast to the low primary kinetic isotope effects (kH/kD) that normally attend syn-β-H elimination processes from σ-alkylmetal species, large values are observed on performing inter- and intramolecular competition experiments with 5. However, the substitution of D for H has negligible effect on the absolute rate at low temperatures (−60 °C). A mechanism to account for this behavior is presented, and implications for asymmetric Heck reactions are noted.Keywords
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