Conversion of hydrosilanes to alkoxysilanes catalyzed by Cp2TiCl2/nBuLi

Article abstract of DOI:10.1016/0022-328X(92)83095-Y

The combination of Cp2TiCl2 and ⁿBuLi provides an effective catalyst for alcoholysis of the model silanes n-HexSiH3, PhMeSiH2, Ph2SiH2 and PhMe2SiH by ethanol, isopropanol, t-butyl alcohol and phenol.Increasing the steric bulk of the substituents on either the alcohol or the silane generally requires longer reaction periods and/or increasing temperature.All SiH bonds are converted to SiOEt groups by ethanol and a single SiH bond in secondary silanes and two SiH bonds in tertiary silanes are replaced by t-butyl alcohol.Diols including pinacol, 2,4-pentanediol and 2,5-hexanediol react with PhRSiH2 (R = Me, Ph) to give 1,3-dioxa-2-silacyclopentanes, -hexanes and -heptanes, respectively.Attempts to form caged structures by condensation of primary silanes and triols was unsuccessful.Hydrolysis of PhRSiH2 is promoted by Cp2TiCl2/n-BuLi and the siloxane is produced in quantitative yield when R = Ph and a mixture of linear disiloxanes and trisiloxanes in addition to cyclopolysilanes are produced when R = Me.Other protic reagents including acids, mercaptans, amines and enolizable ketones did not react.The effects of reaction parameters such as temperature, silane to catalyst ratio, solvent, transition metal and replacements for ⁿBuLi were also determined.