Synthesis of syn- and anti-β-Hydroxy Allylsilanes

Significance

β-Hydroxy allylsilanes 3 comprise important building blocks in synthetic chemistry, thus, development of their stereoselective synthesis is important (see Review below). A variety of access points towards anti-β-hydroxy silanes exist, but the synthesis of syn-β-hydroxy silanes is difficult as a result of the instability of (Z)-γ-silylallylmetal species towards isomerization. The authors found that in combination with a dimethyl­phenylsilyl substituent, ( ^d Ipc)₂B-H yields hydro-boration adducts, which are configurationally stable at below -40 ˚C and yield the kinetic syn products. At higher temperatures the anti products could be obtained.

Review: M. Lombardo, C. Trombini Chem. Rev. 2007, 107, 3843-3879.