Palladium-catalyzed asymmetric cycloadditions of vinylcyclopropanes and in situ formed unsaturated imines: construction of structurally and optically enriched spiroindolenines

Org Lett. 2015 Jan 2;17(1):150-3. doi: 10.1021/ol503383x. Epub 2014 Dec 19.

Abstract

A palladium-catalyzed (3 + 2) cycloaddition of vinyl cyclopropane and α,β-unsaturated imines generated in situ from aryl sulfonyl indoles is reported. The reaction proceeds with high diastereoselectivity to provide the optically enriched spirocyclopentane-1,3'-indolenines in up to 74% yield and with up to 97% ee, which contains an all-carbon quaternary center and two tertiary stereocenters. The reaction involves a first conjugate addition of the carbon anion of zwitterionic π-allylpalladium complex from vinyl cyclopropane to the in situ formed unsaturated imine followed by a palladium-catalyzed intramolecular C3-allylation of indole.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Cycloaddition Reaction
  • Cyclopropanes / chemistry*
  • Imines / chemical synthesis*
  • Imines / chemistry
  • Indoles / chemical synthesis*
  • Indoles / chemistry*
  • Molecular Structure
  • Palladium / chemistry*
  • Spiro Compounds / chemical synthesis*
  • Spiro Compounds / chemistry
  • Stereoisomerism
  • Sulfones / chemistry*
  • Vinyl Compounds / chemistry*

Substances

  • Cyclopropanes
  • Imines
  • Indoles
  • Spiro Compounds
  • Sulfones
  • Vinyl Compounds
  • Palladium