Recent developments in the metal-catalyzed reactions of metallocarbenoids from propargylic esters

Chemistry. 2007;13(5):1350-7. doi: 10.1002/chem.200601522.

Abstract

The transition-metal-catalyzed intramolecular cycloisomerization of propargylic carboxylates provides functionalized bicyclo[n.1.0]enol esters in a very diastereoselective manner and, depending on the structure, with partial or complete transfer of chirality from enantiomerically pure precursors. The subsequent methanolysis gives bicyclo[n.1.0] ketones, hence resulting in a very efficient two-step protocol for the syntheses of alpha,beta-unsaturated cyclopropyl ketones, key intermediates for the preparation of natural products. The results from mechanistic computational studies suggest that they probably proceed through cyclopropyl metallocarbenoids, formed by endo-cyclopropanation, that undergo a 1,2-acyl migration. Finally, the potential of the intermolecular reaction and the related pentannulation of propargylic esters bearing pendant aromatic rings are also discussed.

Publication types

  • Review

MeSH terms

  • Alkynes / chemistry*
  • Biological Products / chemical synthesis*
  • Bridged Bicyclo Compounds, Heterocyclic / chemical synthesis*
  • Catalysis
  • Cyclization
  • Cyclopropanes / chemistry
  • Esters / chemical synthesis*
  • Hydrocarbons / chemistry
  • Ketones / chemical synthesis
  • Methane / analogs & derivatives*
  • Methane / chemistry
  • Methanol / chemistry
  • Models, Chemical
  • Organometallic Compounds / chemistry*
  • Propanols / chemistry*
  • Stereoisomerism
  • Transition Elements / chemistry*

Substances

  • Alkynes
  • Biological Products
  • Bridged Bicyclo Compounds, Heterocyclic
  • Cyclopropanes
  • Esters
  • Hydrocarbons
  • Ketones
  • Organometallic Compounds
  • Propanols
  • Transition Elements
  • carbene
  • propargyl alcohol
  • Methane
  • Methanol