While 1,2-diheteroatom-substituted alkenes represent useful synthetic building blocks, there are no simple, general procedures available for preparation of such compounds. We describe here a simple catalytic procedure based on rhodium C-H bond activation for the synthesis of diheteroatom alkenes of the type R(3)SiOCH=CHG (G = -OR, -NRR').

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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.

Alkenes Alkenes P 0023 Synthesis of 1,2-Diheteroatom-Substituted Alkenes via Rhodium-Catalyzed Intramolecular Hydrogen Transfer. -A convenient protocol for preparation of the title compounds, useful synthetic building blocks, is developed based on a Rh-catalyzed intramolecular hydrogen transfer reaction transforming readily available silyl ethers into silyl enol ethers. -(DIAZ-REQUEJO, M. M.; DISALVO, D.; BROOKHART*, M.; J.