Thermal Rearrangements of α-(Acyloxy)silanes. 2. Formation of Chiral Precursors and Migratory Preference of Silicon-Based Groups

Article abstract of DOI:10.1021/jo00025a024

The asymmetric reduction of acylsilanes to chiral α-hydroxysilanes and the thermal rearrangement of the corresponding chiral α-acetoxysilanes was employed.Ipc2BCl reduces many acylsilanes in > 95percent ee.The rate of the thermal rearrangement of the α-acetoxysilanes was dependent upon the substituents at both silicon and carbon.Evidence is presented to indicate there is electron deficiency at the α-carbon in the transition state.Migratory aptitudes follow those expected on the basis of the migrating group assuming an apical migratory group at a pentacoordinate silicon.A previously unreported hydrolytic transformation of a proposed acylsilyl hydride to a stable 1-sila-1,2-diol was observed.