Intramolecular Hydrogen Transfer Reactions Catalyzed by Pentamethylcyclopentadienyl Rhodium and Cobalt Olefin Complexes: Mechanistic Studies.

Abstract The mechanism of intramolecular transfer dehydrogenation catalyzed by [Cp ∗ M(VTMS) 2 ] ( 1 , M = Rh, 2 , M = Co, Cp ∗  = C 5 Me 5 , VTMS = vinyltrimethylsilane) complexes has been studied using vinyl silane protected alcohols as substrates. Deuterium-labeled substrates have been synthesized and the regioselectivity of H/D transfers investigated using 1 H and 2 H NMR spectroscopy. The labeling studies establish a regioselective pathway consisting of alkene directed α C–H activation, 2,1 alkene insertion, and finally β-hydride elimination to give silyl enol ether products.