sodium tetrahydroborate; chloro-trimethyl-silane in tetrahydrofuran T=20°C; 66 h; Heating / reflux;

chlorotrimethylsilane in tetrahydrofuran byproducts: H2; to stirred suspn. of NaBH4 in THF under Ar wa added ClSiMe3; mixt. heated at reflux for 2 h; cooled to room temp.; pinacol ester added as suspn.in THF; mixt. heated at reflux for 64 h; cooled to room temp.; mixt. quenched (MeOH) over 30 min followed by H2O;solvent partially evapd.; satd. aq. NH4Cl added; 3 M HCl added to pH 1 of aq. layer; CH2Cl2 added; pH adjusted to 9 (Na2CO3) with stirring; sep d.; aq. layer was re-extd. (CH2Cl2)..;