title: Cyclic (Amino)(aryl)carbenes (CAArCs) as Strong σ-Donating and π-Accepting Ligands for Transition Metals.
abstract: Cyclic (amino)(aryl)carbenes (CAArCs) result from the replacement of the alkyl substituent of cyclic (alkyl)(amino) carbenes (CAACs) by an aryl group. This structural modification leads to enhanced electrophilicity of the carbene center with retention of the high nucleophilicity of CAACs, and therefore CAArCs feature a small singlet-triplet gap. The isoindolium precursors are readily prepared in good yields, and deprotonation at low temperature, in the presence of [RhCl(cod)]2 and [(Me2S)AuCl] lead to air-stable rhodium and gold CAArC-supported complexes, respectively. The rhodium complexes promote the [3+2] cycloaddition of diphenylcyclopropenone with ethyl phenylpropiolate, and induce the addition of 2-vinylpyridine to alkenes by CH activation. The gold complexes allow for the catalytic three-component preparation of 1,2-dihydroquinolines from aniline and phenyl acetylene. These preliminary results illustrate the potential of CAArC ligands in transition-metal catalysis.
authors.affiliation: Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710054 (P.R. China).
authors.forename: Bin
authors.initials: B
authors.lastname: Rao
authors.affiliation: Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710054 (P.R. China).
authors.forename: Huarong
authors.initials: H
authors.lastname: Tang
authors.affiliation: Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, 710054 (P.R. China). zengxiaoming@mail.xjtu.edu.cn.|State Key Laboratory of Elemento-organic Chemistry, Nankai University, Tianjin 300071 (P.R. China). zengxiaoming@mail.xjtu.edu.cn.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zeng
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0358 (USA).
authors.forename: Liu Leo
authors.initials: LL
authors.lastname: Liu
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0358 (USA).
authors.forename: Mohand
authors.initials: M
authors.lastname: Melaimi
authors.affiliation: UCSD-CNRS Joint Research Chemistry Laboratory (UMI 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0358 (USA). guybertrand@ucsd.edu.
authors.forename: Guy
authors.initials: G
authors.lastname: Bertrand
keywords: N-heterocyclic carbenes; electronic properties; gold; homogeneous catalysis; rhodium