Intramolecular hydrogen transfer reactions catalyzed by pentamethylcyclopentadienyl rhodium and cobalt olefin complexes: Mechanistic studies

The mechanism of intramolecular transfer dehydrogenation catalyzed by [Cp∗M(VTMS)2] (1, M = Rh, 2, M = Co, Cp∗ = C5Me5, 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 1H and 2H 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.

The mechanism of intramolecular transfer dehydrogenation catalyzed by [Cp∗M(VTMS)2] (M = Rh, Co, Cp∗ = C5Me5) complexes has been studied using vinyl silane protected alcohols as substrates. Using deuterium-labeled substrates, the regioselectivity of H/D transfers was investigated using NMR spectroscopy. These studies establish a regioselective pathway involving alkene directed α-C–H activation, 2,1 alkene insertion, and finally β-hydride elimination to give silyl enol ether products.Figure optionsDownload as PowerPoint slide