Enantioselective epoxidation with chiral MN(III)(salen) catalysts: kinetic resolution of aryl-substituted allylic alcohols

J Org Chem. 2001 Aug 24;66(17):5796-800. doi: 10.1021/jo010350j.

Abstract

A set of aryl-substituted allylic alcohols rac-2 has been epoxidized by chiral Mn(salen*) complexes 1 as the catalyst and iodosyl benzene (PhIO) as the oxygen source. Whereas one enantiomer of the allylic alcohol 2 is preferentially epoxidized to give the threo- or cis-epoxy alcohol 3 (up to 80% ee) as the main product (dr up to >95:5), the other enantiomer of 2 is enriched (up to 53% ee). In the case of 1,1-dimethyl-1,2-dihydronaphthalen-2-ol (2c), the CH oxidation to the enone 4c proceeds enantioselectively and competes with the epoxidation. The absolute configurations of the allylic alcohols 2 and their epoxides 3 have been determined by chemical correlation or CD spectroscopy. The observed diastereo- and enantioselectivities in the epoxidation reactions are rationalized in terms of a beneficial interplay between the hydroxy-directing effect and the attack along the Katsuki trajectory.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Epoxy Compounds / chemical synthesis
  • Epoxy Compounds / chemistry*
  • Kinetics
  • Manganese / chemistry*
  • Organometallic Compounds / chemistry*
  • Oxidation-Reduction
  • Propanols / chemistry*
  • Propanols / isolation & purification
  • Stereoisomerism
  • Substrate Specificity

Substances

  • Epoxy Compounds
  • Organometallic Compounds
  • Propanols
  • allyl alcohol
  • Manganese