Asymmetric cyclopropanation of β,γ-unsaturated α-ketoesters with stabilized sulfur ylides catalyzed by C2-symmetric ureas

J Org Chem. 2011 Jan 7;76(1):281-4. doi: 10.1021/jo101699r. Epub 2010 Dec 8.

Abstract

A novel organocatalytic asymmetric cyclopropanation of β,γ-unsaturated α-ketoesters with stabilized sulfur ylides using C(2)-symmetric urea as a hydrogen-bond catalyst has been described. This reaction allows an efficient access to 1,2,3-trisubstituted cyclopropane derivatives in moderate to good yields with up to 16:1 dr and 90:10 er under mild reaction conditions. The mechanism study proved that the high stereoinduction originated from the cooperative effect of the hydrogen-bond catalyst.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Crystallography, X-Ray
  • Cyclization
  • Cyclopropanes / chemistry*
  • Esters
  • Ketones / chemistry*
  • Magnetic Resonance Spectroscopy
  • Molecular Structure
  • Stereoisomerism
  • Sulfur / chemistry*
  • Urea / chemistry*

Substances

  • Cyclopropanes
  • Esters
  • Ketones
  • Sulfur
  • Urea
  • cyclopropane