Reactions of (Triphenylsilyl)ethylene Oxide with Grignard Reagents (and with MgBr2). A Reinvestigation

Reactions of (triphenylsilyl)ethylene oxide (1) with simple Grignard reagents such as EtMgBr and PhMgBr have been reported to yield crystalline hydroxysilanes assigned as the α-hydroxy silanes expected from β opening of the epoxide. Reinvestigation of these reactions showed that the hydroxysilanes were the β-hydroxy silanes 4 and 7 expected from a rearrangement−trapping sequence; a bromohydrin, assigned as the α-bromo-β-hydroxy silane 9 from α opening, and (triphenylsilyl)acetaldehyde (8) were also formed.