Stereoselective Synthesis of Silacyclohexanols by Silicon Tethered Type II Ene Cyclisation

Vinyl silane precursors for intramolecular ene reaction were prepared either by sequential organometallic substitution of appropriate silyl halides or by ring opening of oxasilacyclopentanes with 2-propenyllithium. The oxasilacyclopentane intermediates were prepared by free-radical cyclisation, intramolecular hydrosilylation, or intramolecular Diels–Alder reaction. Treatment of the ene precursors with methylaluminium dichloride resulted in the formation of silacyclohexanols with high stereoselectivity.