Asymmetric reductions of propargyl ketones. An effective approach to the synthesis of optically-active compounds

M. Mark midland, Alfonso tramontano, Aleksander kazubski, Richard S. graham, David J S tsai, Daniel B. cardin

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Abstract

Propargyl ketones are readily reduced by the asymmetric reducing agent B-3-pinanyl-9- borabicyclo[3.3.1]-nonane (Alpine-borane). The reagent prepared from (+)-α-pinene and 9-BBN provides the R enantiomer while the S enantiomer can be obtained from (-)-α-pinene. Alternatively the S enantiomer can be prepared from the reagent derived from 9-BBN and the benzyl ether of nopol (6,6-dimethyl-bicyclo[3.11.]hept-2-ene-2-ethanol). The limiting factor in obtaining high enantiomeric induction is often the enantiomeric purity of the α-pinene. With 100% enantiomerically pure α-pinene, propargyl alcohols of essentially 100% ee can be obtained. A predictive rationalization of the transition state leading to this remarkable selection is presented. The acetylene unit of the propargyl alcohol provides a convenient handle for transformations to other useful, optically-active products. The use of propargyl alcohols for the synthesis of optically-active α- and β-substituted γ-lactones, and δ-lactones is illustrated.

Original languageEnglish (US)
Pages (from-to)1371-1380
Number of pages10
JournalTetrahedron
Volume40
Issue number8
DOIs
StatePublished - 1984

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ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry
  • Drug Discovery

Cite this

Mark midland, M., tramontano, A., kazubski, A., graham, R. S., tsai, D. J. S., & cardin, D. B. (1984). Asymmetric reductions of propargyl ketones. An effective approach to the synthesis of optically-active compounds. Tetrahedron, 40(8), 1371-1380. https://doi.org/10.1016/S0040-4020(01)82422-4