Enantioselective Ring-Cleavage of meso- Epoxides with beta-Halodiisopinocampheylboranes.

Abstract

B-Halodiisopinocampheylboranes, Ipc2BX, in particular the bromide 1 b, and the iodide 1 c, differentiate between the enantiotopic C-O bonds of meso-epoxides to furnish 1,2-halohydrins of moderate to excellent enantiomeric purity. Thus (-)-(1R, 2R)-2-bromocychlohexanol, (-)-(1R, 2R)-2-iodocyclohexanol, (-)-(1R, 2R)-2-iodocyclohex-4-en-1-o1 and (-)-(1R, 2R)-2-bromoxcyclohex-4-en-1-o1 are obtained in 84%, 91%, 63% and 95% ee respectively from the corresponding meso-epoxides and haloborane reagents. Simple recrystallization from pentane then gives halohydrins of essentially 100% ee; cis-2-butene oxide and cis-3-hexene oxide furnish the corresponding (1R, 2R)-iodohydrins in 78 and 69% ee respectively. In all cases the S carbon of the meso-epoxide is selectively cleaved. This is the first example of enantioselective ring cleavage of meso-epoxides to obtain optically active 1,2-halohydrins. Keywords: Epoxides, Boranes. (mjm)

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Document Details

Document Type
Technical Report
Publication Date
May 17, 1988
Accession Number
ADA195691

Entities

People

  • Herbert C. Brown
  • M. Srebnik
  • N. N. Joshi

Organizations

  • Purdue University

Tags

DTIC Thesaurus Topics

  • Abstracts
  • Alkenes
  • Chemical Synthesis
  • Chemistry
  • Column Chromatography
  • Crystal Structure
  • Crystallography
  • Cyclic Hydrocarbons
  • Cyclohexenes
  • Halohydrins
  • Lewis Acids
  • Military Research
  • Organic Chemistry
  • Procurement
  • United States
  • United States Government
  • X Rays

Fields of Study

  • Chemistry

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