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 alpha- and beta-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.