The synthesis and directed dihydroxylation of a series of homoallylic alcohols and trichloroacetamides is described. Using the combination of OsO4 and TMEDA, moderate to high levels of stereoselectivity were obtained, depending upon the structure of the substrate. Proof of the structure of two osmate esters was obtained through X-ray crystallography.
Scope of the directed dihydroxylation: application to cyclic homoallylic alcohols and trihaloacetamides
作者:Timothy J. Donohoe、Lee Mitchell、Michael J. Waring、Madeleine Helliwell、Andrew Bell、Nicholas J. Newcombe
DOI:10.1039/b303081d
日期:——
The synthesis and directed dihydroxylation of a range of cyclic alkenes was investigated. Both homoallylic alcohols and homoallylic trihaloacetamides were found to be efficient directing groups, giving rise to good to excellent levels of remote asymmetric induction with OsO4–TMEDA. Interestingly, in all cases examined, trifluoroacetamides were found to be superior to trichloroacetamides as directing groups and an argument is presented which rationalises this observation.