The First Tri- and Tetraalkoxysilanes with Four Different Substituents

Unsymmetrically substituted tri- and tetraalkoxysilanes were surprisingly found to be configurationally stable and easy to prepare. It was found that compounds of type MeSi(OR)(2)(OR'), MeSi(OR)(OR')(OR"), Si(OR)(2)(OR')(2), Si(OR)(2)(OR')(OR"), Si(OR)(3)(OR'), and even Si(OR)(OR')(OR")(OR) could be obtained by sequential addition of a variety of chiral and achiral alcohols to methyltrichlorosilane or tetrachlorosilane in the presence of pyridine. In the case of MeSi(OR)(OR')(OR") and Si(OR)(OR')(OR")(OR), two types of compounds that have never been prepared before, were obtained in good yield.