Palladium-Catalyzed Meta-Selective C-H Bond Activation with a Nitrile-Containing Template: Computational Study on Mechanism and Origins of Selectivity.
Density functional theory investigations have elucidated the mechanism and origins of meta-regioselectivity of Pd(II)-catalyzed C-H olefinations of toluene derivatives that employ a nitrile-containing template. The reaction proceeds through four major steps: C-H activation, alkene insertion, β-hydri...
| Publicado en: | Journal of the American Chemical Society Vol. 136; no. 1; pp. 344 - 356 |
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| Autores principales: | , , , , , , , , , |
| Formato: | Artículo |
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American Chemical Society
1/8/2014
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=93882915&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 93882915 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 1/8/2014 vid: 136 iid: 1 pid: 997 pub: American Chemical Society artinfo: ui: 93882915 10.1021/ja410485g ppf: 344 ppct: 12 formats: tig: atl: Palladium-Catalyzed Meta-Selective C-H Bond Activation with a Nitrile-Containing Template: Computational Study on Mechanism and Origins of Selectivity. aug: au: Yun-Fang Yang Gui-Juan Cheng Peng Liu Dasheng Leow Tian-Yu Sun Ping Chen Xinhao Zhang Jin-Quan Yu Yun-Dong Wu Houk, K. N. affil: Laboratory of Computational Chemistry and Drug Design and Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen 518055, China Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China su: Palladium catalysts Activation (Chemistry) Carbon-hydrogen bonds Nitriles Catalyst selectivity Density functional theory Regioselectivity (Chemistry) Toluene sug: subj: Palladium catalysts Activation (Chemistry) Carbon-hydrogen bonds Nitriles Catalyst selectivity Density functional theory Regioselectivity (Chemistry) Toluene ab: Density functional theory investigations have elucidated the mechanism and origins of meta-regioselectivity of Pd(II)-catalyzed C-H olefinations of toluene derivatives that employ a nitrile-containing template. The reaction proceeds through four major steps: C-H activation, alkene insertion, β-hydride elimination, and reductive elimination. The C-H activation step, which proceeds via a concerted metalation-deprotonation (CMD) pathway, is found to be the rate- and regioselectivity-determining step. For the crucial C- H activation, four possible active catalytic species—monomeric Pd(OAc), dimeric Pd(OAc), heterodimeric PdAg- (OAc), and trimeric Pd(OAc)—have been investigated. The computations indicated that the C-H activation with the nitrilecontaining template occurs via a Pd-Ag heterodimeric transition state. The nitrile directing group coordinates with Ag while the Pd is placed adjacent to the meta-C-H bond in the transition state, leading to the observed high meta-selectivity. The Pd(OAc) dimeric mechanism also leads to the meta-C-H activation product but with higher activation energies than the Pd-Ag heterodimeric mechanism. The Pd monomeric and trimeric mechanisms require much higher activation free energies and are predicted to give ortho products. Structural and distortion energy analysis of the transition states revealed significant effects of distortions of the template on mechanism and regioselectivity, which provided hints for further developments of new templates. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2014 holdings: @attributes: islocal: N |
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