THE ASYMMETRIC HYDROBORATION OF SIMPLE ALKENYLSILANES: CHIRAL α-SILYLALKYL-BORANES AND ALCOHOLS

Article abstract of DOI:10.1016/S0040-4020(01)86654-0

The detailed study of the asymmetric hydroboration of various vinylsilanes with monoisopinocampheylborane (IPCBH2) is presented.In all cases, β substitution on the vinylsilane gives monomeric dialkylborane adducts with the boryl group α to the silicon.These studies shown that the larger the groups on silicon are, the more positive the influence on the enatioselectivity of the process.Moderate asymmetric induction (24-40percent) is observed only for vinyl silanes wich contain a substituent trans to the silicon.A model for the asymmetric hydroboration of alkenes with this reagent is proposed.The complete charactarization of the borane intermediates was achieved employing NMR (11B, 13C, 1H, 29Si).