Synthesis of 3-aryl-2-arylamidobenzofurans based on the Curtius rearrangement

J Org Chem. 2011 Apr 15;76(8):2502-20. doi: 10.1021/jo102265b. Epub 2011 Mar 10.

Abstract

The synthesis of novel 3-aryl-2-arylamidobenzofurans has been accomplished via a Curtius rearrangement strategy in four steps from benzofuran-2-carboxylic acids. The requisite Suzuki-Miyaura cross-coupling, with benzyl 3-bromobenzofuran-2-ylcarbamate or 2-arylamido-3-bromobenzofurans, revealed an unusual reductive debromination process due to the presence of the free NH group. This dehalogenation can be suppressed by N-alkylation. DMAP is an efficient reagent for the one-pot conversion of benzyl benzofuran-2-ylcarbamates into the corresponding benzofuran-2-arylamides through aroylation, thus acting both as an acyl transfer reagent and a deprotecting agent of the Cbz group. A mechanism is postulated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Aminopyridine / analogs & derivatives
  • 4-Aminopyridine / chemistry
  • Alkylation
  • Amides / chemistry
  • Amines / chemistry
  • Benzofurans / chemical synthesis*
  • Biological Products / chemical synthesis*
  • Boronic Acids / chemistry
  • Carboxylic Acids / chemistry
  • Catalysis
  • Chemistry, Pharmaceutical / methods*
  • Stereoisomerism

Substances

  • Amides
  • Amines
  • Benzofurans
  • Biological Products
  • Boronic Acids
  • Carboxylic Acids
  • 4-Aminopyridine
  • 4-dimethylaminopyridine