Enantioselective cyclizations of silyloxyenynes catalyzed by cationic metal phosphine complexes

J Am Chem Soc. 2012 Feb 8;134(5):2742-9. doi: 10.1021/ja210388g. Epub 2012 Jan 31.

Abstract

The discovery of complementary methods for enantioselective transition metal-catalyzed cyclization with silyloxyenynes has been accomplished using chiral phosphine ligands. Under palladium catalysis, 1,6-silyloxyenynes bearing a terminal alkyne led to the desired five-membered ring with high enantioselectivities (up to 91% ee). As for reactions under cationic gold catalysis, 1,6- and 1,5-silyloxyenynes bearing an internal alkyne furnished the chiral cyclopentane derivatives with excellent enantiomeric excess (up to 94% ee). Modification of the substrate by incorporating an α,β-unsaturation led to the discovery of a tandem cyclization. Remarkably, using silyloxy-1,3-dien-7-ynes under gold catalysis conditions provided the bicyclic derivatives with excellent diastereo- and enantioselectivities (up to >20:1 dr and 99% ee).

Publication types

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

MeSH terms

  • Alkynes / chemistry*
  • Cations / chemistry
  • Cyclization
  • Gold / chemistry*
  • Molecular Structure
  • Organosilicon Compounds / chemistry*
  • Phosphines / chemistry*
  • Stereoisomerism

Substances

  • Alkynes
  • Cations
  • Organosilicon Compounds
  • Phosphines
  • Gold
  • phosphine