Tunable Pd-catalyzed cyclization of indole-2-carboxylic acid allenamides: carboamination vs microwave-assisted hydroamination

J Org Chem. 2010 Oct 15;75(20):6923-32. doi: 10.1021/jo101501u.

Abstract

A variety of 3-vinyl-substituted imidazo[1,5-a]indole derivatives were synthesized by intramolecular Pd-catalyzed cyclization of the title allenamides through either a domino carbopalladation/exo-cyclization process or a novel hydroamination reaction that proceeds smoothly under microwave irradiation. Both the observed pathways involve a π-allyl-palladium(II) complex arising from insertion of the allene group into a palladium(II) species, the latter being formed in situ by the intervention of an aryl iodide or of the N-H group. In both cases, the role of nucleophile is covered by the indole nitrogen.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides / chemical synthesis*
  • Amides / chemistry
  • Amination
  • Carboxylic Acids
  • Catalysis
  • Cyclization
  • Indoles / chemistry*
  • Microwaves*
  • Molecular Structure
  • Palladium / chemistry*
  • Stereoisomerism

Substances

  • Amides
  • Carboxylic Acids
  • Indoles
  • indole-2-carboxylic acid
  • Palladium