Mechanistic Elucidation of the Arylation of Non-Spectator N-Heterocyclic Carbenes at Copper Using a Combined Experimental and Computational Approach

Thomas J. Williams, Joshua T.W. Bray, Benjamin R.M. Lake, Charlotte E. Willans, Nasir A. Rajabi, Alireza Ariafard, Chiara Manzini, Fabio Bellina, Adrian C. Whitwood, Ian J.S. Fairlamb

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Abstract

CuI(NHC)Br complexes (NHC = N-heterocyclic carbene) undergo a direct reaction with iodobenzene to give 2-arylated benzimidazolium products. The nature of the N-substituent on the NHC ligand influences the reactivity of the CuI(NHC)Br complex toward arylation. N-Benzyl or N-phenyl substituents facilitate arylation, whereas N-mesityl substituents hinder arylation. Density functional theory calculations show that an oxidative addition/reductive elimination pathway involving CuIII species is energetically feasible. A less hindered CuI(NHC)Br complex with N-benzyl groups is susceptible to oxidation reactions to give 1,3-dibenzylbenzimidazolium cations containing a CuIBr anion (various polymorphs). The results described herein are of relevance to C-H functionalization of (benz)azoles. (Chemical Equation Presented).

Original languageEnglish
Pages (from-to)3497-3507
Number of pages11
JournalOrganometallics
Volume34
Issue number14
Early online date7 Jul 2015
DOIs
Publication statusPublished - 27 Jul 2015

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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    Williams, T. J., Bray, J. T. W., Lake, B. R. M., Willans, C. E., Rajabi, N. A., Ariafard, A., Manzini, C., Bellina, F., Whitwood, A. C., & Fairlamb, I. J. S. (2015). Mechanistic Elucidation of the Arylation of Non-Spectator N-Heterocyclic Carbenes at Copper Using a Combined Experimental and Computational Approach. Organometallics, 34(14), 3497-3507. https://doi.org/10.1021/acs.organomet.5b00093