Silicon Tethered Alkenyl Transfer and Type I Ene Reactions

A range of vinyl silanes was prepared in order to investigate the possibility of effecting silicon tethered Type I ene cyclisations analogous to our previously reported Type II variant. Some of these substrates were found to undergo overall stereospecific alkenyl transfer via silacyclopentanol intermediates; in a homologous series, alkenyl transfer was accompanied by dehydration to provide 7-silylhepta-2,4-dienes in moderate yield. Formal Type I ene cyclisations were found to be successful for allysilane precursors resulting in the stereoselective formation of silacyclohexanols.