Efficient and practical synthesis of 4(5)-aryl-1H-imidazoles and 2,4(5)-diaryl-1H-imidazoles via highly selective palladium-catalyzed arylation reactions

J Org Chem. 2007 Oct 26;72(22):8543-6. doi: 10.1021/jo701496p. Epub 2007 Oct 2.

Abstract

4(5)-aryl-1H-imidazoles can be efficiently and selectively prepared by PdCl2(dppf)-catalyzed Suzuki-Miyaura reaction of commercially available 4(5)-bromo-1H-imidazole with arylboronic acids under phase-transfer conditions. On the other hand, N-unprotected 4(5)-aryl-1H-imidazoles can undergo highly selective Pd(OAc)2-catalyzed and CuI-mediated direct C-2-arylation with a variety of aryl bromides and iodides under base-free and ligandless conditions to produce 2,4(5)-diaryl-1H-imidazoles in modest to good yields. No N-arylation byproducts are observed under the experimental conditions used to prepare 2,4(5)-diaryl-1H-imidazoles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Imidazoles / chemical synthesis*
  • Imidazoles / chemistry
  • Molecular Structure
  • Palladium / chemistry*

Substances

  • Imidazoles
  • Palladium