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Keywords:

  • aryl bromides;
  • atom-economy;
  • C[BOND]H bond activation;
  • palladium;
  • pyrroles

Abstract

A simple and atom-economical procedure for the regioselective C-2 or C-5 arylation of pyrroles via a C[BOND]H bond activation is reported. Only 0.5–0.01 mol% of commercially available and air-stable ligand-free palladium(II) acetate [Pd(OAc)2] was employed as the catalyst. The presence of electron-withdrawing substituents such as formyl, acetyl or ester at the C-2 position of the pyrrole is tolerated. This environmentally attractive procedure has also been found to be tolerant to a very wide variety of functional groups on the aryl bromides such as formyl, acetyl, propionyl, ester, nitrile, nitro, fluoro, methoxy, amino or trifluoromethyl.