Use of an aminosilyllithium for the diastereoselective synthesis of diphenyl oxasilacyclopentane acetals and polyols

[reaction: see text] The conjugate addition reaction of a stable, in situ generated silyllithium gives a beta-hydroxysilyl ester with high diastereoselectivity. Conversion of the beta-hydroxysilyl ester to a beta-fluorosilyl ester affords the precursor to the oxasilacyclopentane acetal in high yields under mild conditions. A hydride reduction and subsequent intramolecular silylation lead to the acetal in excellent yields. Finally, highly selective nucleophilic substitution affords oxasilacyclopentanes, which undergo a mild oxidation to afford 1,3-trans diols with high selectivity.