Organocatalytic asymmetric robinson annulation of alpha,beta-unsaturated aldehydes: applications to the total synthesis of (+)-palitantin

J Org Chem. 2007 Oct 26;72(22):8459-71. doi: 10.1021/jo701477v. Epub 2007 Oct 6.

Abstract

The highly enantioselective organocatalytic Robinson annulation of alpha,beta-unsaturated aldehydes was achieved, catalyzed by l-proline and trialkylamines and providing the formal [4 + 2] cycloaddition adducts. Additionally, in some examples in the catalysis with diarylpyrrolinol silyl ethers, the reactions afforded the [4 + 2] adducts with high enantioselectivity (>99.5% ee). The structure of the adduct, obtained from the reaction of 3-methylbut-2-enal and (E)-3-(2-nitrophenyl)acrylaldehyde, was confirmed by X-ray analysis. The absolute configurations of some [4 + 2] cycloadducts were investigated, and the methodology was applied in the synthesis of (+)-palitantin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes / chemical synthesis
  • Aldehydes / chemistry*
  • Amines / chemistry*
  • Catalysis
  • Crystallography, X-Ray
  • Cyclization
  • Cyclohexanols / chemical synthesis*
  • Cyclohexanols / chemistry
  • Cyclohexanones / chemical synthesis*
  • Cyclohexanones / chemistry
  • Models, Molecular
  • Molecular Structure
  • Proline / chemistry*
  • Stereoisomerism

Substances

  • Aldehydes
  • Amines
  • Cyclohexanols
  • Cyclohexanones
  • palitantin
  • Proline