RUTHENIUM CATALYZED OXIDATION OF HALOINDOLES TO ISATINS
作者:Gordon W. Gribble、Yanbing Liu
DOI:10.1080/00304940109356623
日期:2001.12
involves the oxidation of indoles (1) to isatins (2). Panick and co-workers reported that indoles and 3-bromoindoles are converted to 3,3-dibromooxindoles by treatment with Nbromosuccinimide followed by hydrolysis to isatins? In continuation of our interest in the synthesis and chemistry of 2and 3-haloindole~,~ we now wish to report a new synthesis of isatins from indoles.
Decarboxylative Halogenation and Cyanation of Electron-Deficient Aryl Carboxylic Acids via Cu Mediator as Well as Electron-Rich Ones through Pd Catalyst under Aerobic Conditions
作者:Zhengjiang Fu、Zhaojie Li、Yuanyuan Song、Ruchun Yang、Yanzhu Liu、Hu Cai
DOI:10.1021/acs.joc.5b02873
日期:2016.4.1
and electron-rich ones by employing Pd(II) as catalyst under aerobic conditions have been established, which lead to smooth synthesis of aryl halides (−I, Br, and Cl) through the decarboxylative functionalization of benzoic acids with readily available halogen sources CuX (X = I, Br, Cl), and easy preparation of benzonitriles from decarboxylative cyanation of aryl carboxylic acids with nontoxic and
TBAX/Oxone‐Mediated Halogenation of Pyrazoles and Other Heterocycles: An Entry to Important Cross‐Coupling Reactions
作者:Jaspreet Kour、Pratiksha Khajuria、Alpa Sharma、Sanghapal D. Sawant
DOI:10.1002/asia.202200778
日期:2022.11.16
A facile green approach has been established for halogenation of pyrazoles and different heterocycles via a microwave-mediated protocol using TBAX/Oxone in EtOH. Applications and extension of the method have been demonstrated by presenting various coupling reactions of halogenated pyrazoles.
Efficient Reagents for the Synthesis of 5-, 7-, and 5,7-Substituted Indoles Starting from Aromatic Amines: Scope and Limitations
作者:Jesús Ezquerra、Concepción Pedregal、Carlos Lamas、José Barluenga、Marta Pérez、Miguel Angel García-Martín、José M. González
DOI:10.1021/jo952119+
日期:1996.1.1
Upon reaction with IPy(2)BF(4), 4-substituted anilines give regioselectively the corresponding o-iodoanilines in nearly quantitative yield, in a process that can be carried out on a multigram scale. Palladium-catalyzed coupling of the resulting 2-iodoanilines with (trimethylsilyl)acetylene (TMSA), followed by efficient CuI-mediated nitrogen cyclization onto alkynes with concurrent elimination of the TMS substituent, allows a straightforward elaboration of 5-mono- and 5,7-disubstituted indoles from aromatic amines. This new approach to the aforementioned indoles does not requires protective groups on nitrogen at any step and can be adapted for preparing related 7-manosubstituted indoles. Moreover, examples iterating the process are given, allowing bis-annulation and sequential double annulation and resulting in synthesis of benzodipyrroles. Additionally, suitable conditions for iodination of some of the target indoles with IPy(2)BF(4) are discussed.
Selective C-3 lithiation of 2,3-dibromo- and 2,3-diiodo-1-methylindoles
Reaction of 2,3-dibromo-1-methylindole with tert-butyllithium at -78 degrees C followed by treatment with tropylium ion gave 2-bromo-3-cycloheptatrienyl-1-methylindole in a moderate yield, indicating that 2-bromo-3-lithio-1-methylindole would be involved as, an intermediate instead of 3-bromo-2-lithio-1-methylindole. The structure of 2-bromo-3-cycloheptatrienyl-1-methylindole was unequivocally determined by a single X-ray analysis. 2,3-Diiodo-1-methylindole also gave a 3-lithio derivative exclusively. (c) 2006 Elsevier Ltd. All rights reserved.