Stereoselective 1,2-additions of alpha-alkoxymethyllithiums to aldehydes.
[reaction: see text]. A chiral derivative of tributylstannylmethanol, readily prepared from L-valine, undergoes Sn-Li exchange to provide an alpha-alkoxyorganolithium that adds to aldehydes with up to 91:9 dr. The diastereoselectivity depends on the solvent and alkyllithium used for transmetalation. Treatment of adducts with acid allowed recovery of the chiral auxiliary and diol with complete stereochemical integrity.
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Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry (GWC)(2), Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L3G1.
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