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

TY - JOUR

T1 - Mechanistic Elucidation of the Arylation of Non-Spectator N-Heterocyclic Carbenes at Copper Using a Combined Experimental and Computational Approach

AU - Williams, Thomas J.

AU - Bray, Joshua T W

AU - Lake, Benjamin R M

AU - Willans, Charlotte E.

AU - Rajabi, Nasir A.

AU - Ariafard, Alireza

AU - Manzini, Chiara

AU - Bellina, Fabio

AU - Whitwood, Adrian C.

AU - Fairlamb, Ian J S

PY - 2015/7/27

Y1 - 2015/7/27

N2 - 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).

AB - 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).

UR - http://www.scopus.com/inward/record.url?scp=84938125412&partnerID=8YFLogxK

U2 - 10.1021/acs.organomet.5b00093

DO - 10.1021/acs.organomet.5b00093

M3 - Article

AN - SCOPUS:84938125412

SN - 0276-7333

VL - 34

SP - 3497

EP - 3507

JO - Organometallics

JF - Organometallics

IS - 14

ER -