Enantioselective carbonyl allylation, crotylation, and tert-prenylation of furan methanols and furfurals via iridium-catalyzed transfer hydrogenation

J Org Chem. 2010 Mar 5;75(5):1795-8. doi: 10.1021/jo902697g.

Abstract

5-Substituted-2-furan methanols 1a-c are subject to enantioselective carbonyl allylation, crotylation and tert-prenylation upon exposure to allyl acetate, alpha-methyl allyl acetate, or 1,1-dimethylallene in the presence of an ortho-cyclometalated iridium catalyst modified by (R)-Cl,MeO-BIPHEP, (R)-C3-TUNEPHOS, and (R)-C3-SEGPHOS, respectively. In the presence of 2-propanol, but under otherwise identical conditions, the corresponding substituted furfurals 2a-c are converted to identical products of allylation, crotylation, and tert-prenylation. Optically enriched products of carbonyl allylation, crotylation, and reverse prenylation 3b, 4b, and 5b were subjected to Achmatowicz rearrangement to furnish the corresponding gamma-hydroxy-beta-pyrones 6a-c, respectively, with negligible erosion of enantiomeric excess.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / chemistry*
  • Allyl Compounds / chemistry*
  • Catalysis
  • Furaldehyde / chemistry*
  • Furans / chemistry*
  • Hydrogenation
  • Iridium / chemistry*
  • Methanol / chemistry*
  • Molecular Structure
  • Pyrones / chemistry*
  • Stereoisomerism

Substances

  • Acetates
  • Allyl Compounds
  • Furans
  • Pyrones
  • Iridium
  • Furaldehyde
  • allyl acetate
  • furan
  • methyl acetate
  • Methanol