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Palladium-Catalyzed Sequential Cross-Coupling/Annulation of ortho-Vinyl Bromobenzene with Aryl Bromide: Bimetallic Pathway versus Pd(II)-Pd(IV) Pathway: A DFT Investigation.
Zhang, Jing-Xuan; Shi, Yu-Bing; Tan, Xue; Duan, Liangfei; Zhang, Lei; Meng, Guang-Hao; Mu, Wei-Hua.
Afiliação
  • Zhang JX; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
  • Shi YB; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
  • Tan X; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
  • Duan L; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
  • Zhang L; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
  • Meng GH; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
  • Mu WH; Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092, China.
J Org Chem ; 89(7): 4406-4422, 2024 Apr 05.
Article em En | MEDLINE | ID: mdl-38512313
ABSTRACT
The palladium-catalyzed sequential cross-coupling/annulation of ortho-vinyl bromobenzenes with aryl bromides generating phenanthrenes was characterized by density functional theory (DFT). The Pd(II)-Pd(IV) pathway (Path V) is shown to be less probable than the bimetallic pathway (Path I), the latter proceeding via the following six

steps:

oxidative addition, vinyl-C(sp2)-H activation, Pd(II)-Pd(II) transmetalation, C-C coupling, aryl-C(sp2)-H activation, and reductive elimination. The aryl-C(sp2)-H activation process acts as the rate-determining step (RDS) of the entire chemical transformation, with an activation free energy barrier of ca. 27.4-28.8 kcal·mol-1, in good agreement with the corresponding experimental data (phenanthrenes' yields of ca. 65-90% at 130 °C after 5 h of reaction). The K2CO3 additive effectively reduces the activation free energy barrier of the RDS through direct participation in the reaction while preferentially modulating the charge distributions and increasing the stability of corresponding intermediates and complexes along the reaction path. Furthermore, bonding and electronic structure analyses of the key structures indicate that the chemo- and regioselectivities of the reaction are strongly influenced by both electronic effects and steric hindrance.

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2024 Tipo de documento: Article

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Ano de publicação: 2024 Tipo de documento: Article