N–O Bond as External Oxidant in Group 9 Cp*M(III)-Catalyzed Oxidative C–H Coupling Reactions
作者:Xu-Ge Liu、Hui Gao、Shang-Shi Zhang、Qingjiang Li、Honggen Wang
DOI:10.1021/acscatal.7b00677
日期:2017.8.4
catalyzed by group 9 Cp*M(III) complexes. By using Cp*Rh(III)-catalyzed isocoumarin synthesis as a model reaction, experimental and theoretical mechanistic studies were conducted. The results concluded that the Rh(III)–Rh(I)–Rh(III) rather than the Rh(III)–Rh(V)–Rh(III) pathway is more likely involved in the mechanism, and both the C–H activation and oxidation of the Cp*Rh(I) species were involved in
Waste-Free Synthesis of Condensed Heterocyclic Compounds by Rhodium-Catalyzed Oxidative Coupling of Substituted Arene or Heteroarene Carboxylic Acids with Alkynes
of 2-amino- and 2-hydroxybenzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding 8-substituted isocoumarinderivatives, some of which exhibit solid-state fluorescence. Depending on conditions, 4-ethenylcarbazoles can be synthesized selectively from 2-(arylamino)benzoic acids. The oxidative coupling reactions of
Aerobic oxidative CH functionalizations of weakly coordinating benzoic acids have been accomplished with versatile ruthenium(II) biscarboxylates under ambient oxygen or air. Mechanistic studies identified the key factors controlling the elementary step of the oxidation of the ruthenium(0) complex.
Ruthenium(II)-Catalyzed Synthesis of Pyrrole- and Indole-Fused Isocoumarins by C−H Bond Activation in DMF and Water
作者:Keisham S. Singh、Sneha G. Sawant、Pierre H. Dixneuf
DOI:10.1002/cctc.201501261
日期:2016.3.18
Pyrrole‐ and indole‐fused isocoumarins constitute important structural units in natural products and pharmacophores, although the direct and selective bifunctionalization of pyrrole and indole remain a challenge. Herein, we report a one‐pot synthesis of pyrrole‐ and indole‐fused isocoumarins from simple 1‐methylpyrrole‐2‐carboxylic acid and 1‐methylindole‐3‐carboxylic acid by annulation with alkynes
An inexpensive cationic ruthenium(II) catalyst enabled the expedient synthesis of isocoumarins through oxidative annulations of alkynes by benzoic acids. This C-H/O-H bond functionalization process also proved applicable to the preparation of alpha-pyrones and was shown to proceed by rate-limiting C-H bond ruthenation.