More than a Protective Group:  Synthesis and Applications of a New Chiral Silane

Enantiomerically pure (−)-(R)- and (+)-(S)-(1-methoxy-2,2,2-triphenylethyl)dimethylsilanes (MOTES-H) were synthesized from triphenylacetaldehyde in five synthetic steps and with 60% overall yield. MOTES-protected α- and β-hydroxycarbonyl compounds were used in Grignard and Diels−Alder reactions in the presence of MgBr₂ to afford addition products with 87−98% yield and selectivities of up to >120:1 dr. With this method, the pine beetle pheromone (−)-frontalin (67%, 98.5% ee) and naturally occurring (−)-(R)-octane-1,3-diol (90%, >99% ee) were synthesized.