- Rhodium-catalyzed C-H-CO-olefin coupling reactions - A chelation-assisted direct carbonylation at the ortho C-H bond in the benzene ring of 2-arylpyridines
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The reaction of 2-arylpyridines with ethylene and carbon monoxide in the presence of a catalytic amount of Rh4(CO)12 results in selective carbonylation at the ortho C-H bond. The reaction is heavily dependent on the solvents used, wi
- Chatani, Naoto,Uemura, Takeshi,Asaumi, Taku,Ie, Yutaka,Kakiuchi, Fumitoshi,Murai, Shinji
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- Ru/C-catalyzed carbonylation at ortho-C-H bonds in 2-phenylpyridines
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Ru/C also exhibits catalytic activity for carbonylation at ortho-C-H bonds in 2-phenylpyridines. Georg Thieme Verlag Stuttgart.
- Imoto, Shinya,Uemura, Takeshi,Kakiuchi, Fumitoshi,Chatani, Naoto
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- Ru3(CO)12-Catalyzed Reaction of Pyridylbenzenes with Monoxide and Olefins. Carbonylation at a C-H Bond in the Benzene Ring
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A ruthenium-catalyzed carbonylation at a C-H bond in a benzene ring is described. The reaction of pyridylbenzenes with CO (20 atm) and ethylene in toluene at 160°C in the presence of a catalytic amount of Ru3(CO)12 results in propionylation at an ortho C-H bond in the benzene ring. Carbonylation does not occur at the pyridine ring, although this is necessary as a directing group to promote the reaction. Olefins such as trimethylvinylsilane and tert-butylethylene in place of ethylene can also be used in this reaction, however 1-hexene, cyclohexene, allyltrimethylsilane, styrene, methyl methacrylate, vinyl acetate, triethoxyvinylsilane, and isopropenyltrimethylsilane do not afford the coupling products. Transition metal complexes, other than ruthenium carbonyl, examined thus far, do not show catalytic activity. In the reaction of meto-substituted pyridylbenzenes, such as those having Me, OMe, CF3, and COOMe group at the meta position in the benzene ring, carbonylation takes place at the less hindered C-H bond exclusively, irrespective of the electronic nature of the substituents. It is apparent that steric factors are more important for the control of regioselectivity. The reaction is also applicable to naphthyl and thienyl rings. Six-membered heterocycles, such as 2-pyrimidine and 4-pyrimidine, are also effective directing groups for carbonylation at a C-H bond in the benzene ring. The present reaction represents the first, effective catalytic carbonylation reaction involving cleavage of the benzene C-H bond.
- Chatani, Naoto,Ie, Yutaka,Kakiuchi, Fumitoshi,Murai, Shinji
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- Monodisperse CuPd alloy nanoparticles as efficient and reusable catalyst for the C (sp2)–H bond activation
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Metal-catalyzed selective activation of C–H bonds is very important for the construction of a variety of biologically active molecules. Supported alloy nanoparticles are of great interest in various catalytic applications due to the synergistic effects between different metals. Here, well-dispersed CuPd alloy nanoparticles supported on reduced graphene oxide (rGO) were synthesized and found to be highly efficient and recyclable catalyst for the chelation-assisted C (sp2)–H bond activation. Aromatic ketones or esters were synthesized via the cross-dehydrogenative coupling (CDC) reaction between 2-arylpyridines and alcohols or acids. Moreover, the catalyst was recovered and used for five times without significantly losing activity.
- Huang, Fei,Wang, Feifan,Hu, Qiyan,Tang, Lin,Xu, Dongping,Fang, Yang,Zhang, Wu
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- Silver catalyzed pyridine-directed acceptorless dehydrogenation of secondary alcohols
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A silver catalyzed pyridine-directed acceptorless dehydrogenation of secondary benzyl alcohols was developed. This general procedure delivers ketones with high atom-economy and hydrogen was the sole byproduct. This dehydrogenation reaction has a good functional group tolerance and high efficiency (up to 90% yield and 10,000/1 substrates-to-catalyst ratio).
- Zhuang, Xin,Tao, Jing,Luo, Zhen,Hong, Chuan-Ming,Liu, Zheng-Qiang,Li, Qing-Hua,Ren, Li-Qing,Luo, Qun-Li,Liu, Tang-Lin
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p. 245 - 249
(2021/02/03)
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- Dual photoredox/palladium-catalyzed C-H acylation of 2-arylpyridines with oxime esters
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An unprecedented dual photoredox/palladium-catalyzed iminyl-radical-mediated C-C bond cleavage and directed ortho C-H acylation of 2-arylpyridines by using oxime esters is described. Oxime esters can serve as efficient acyl sources through formation of the corresponding acyl radicals by photoredox-catalyzed iminyl-radical-mediated C-C bond cleavage. This redox-neutral protocol features excellent regioselectivity, a broad substrate scope, and good functional-group tolerance with respect to both components, giving a broad range of aryl ketones with generally good yields.
- He, Bin-Qing,Gao, Yuan,Wang, Peng-Zi,Wu, Hong,Zhou, Hong-Bin,Liu, Xiao-Peng,Chen, Jia-Rong
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supporting information
p. 373 - 377
(2020/09/11)
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- Ag1Pd1-rGO nanocomposite as recyclable catalyst for CDC reactions of 2-arylpyridines with aldehydes
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Ag1Pd1 nanoparticle-reduced graphene oxide (Ag1Pd1-rGO) nanocomposite was used as an efficient catalyst for the synthesis of aromatic ketones via cross dehydrogenative coupling (CDC) reactions of 2-arylpyridines
- Hu, Qiyan,Liu, Xiaowang,Huang, Fei,Wang, Feifan,Li, Qian,Zhang, Wu
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- Palladium-catalyzed synthesis of aromatic ketones and isoindolobenzimidazoles via selective aromatic C-H bond acylation
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A convenient and efficient palladium-catalyzed synthesis of aromatic ketones and isoindolobenzimidazoles has been developed via selective aromatic C-H bond acylation. The protocol uses palladium acetate as the catalyst, readily available carboxylic acids as the acylating reagents, trifluoroacetic anhydride as the activated agent of the acids, and the corresponding aromatic ketones and isoindolobenzimidazoles were obtained in good to excellent yields. This finding should provide a new and useful strategy for synthesis of aromatic ketones and isoindolobenzimidazoles.
- Lu, Juyou,Zhang, Hao,Chen, Xiaowu,Liu, Hongxia,Jiang, Yuyang,Fu, Hua
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p. 529 - 536
(2013/05/08)
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- Direct carbo-acylation reactions of 2-arylpyridines with α-diketones via Pd-catalyzed C-H activation and selective C(sp2)-C(sp2) cleavage
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An efficient carbo-acylation reaction of 2-arylpyridines with α-diketones via Pd-catalyzed C-H bond activation and C-C bond cleavage in the presence of TBHP was developed that generated aryl ketones in good yields. The highly selective formation of aryl ketones was observed when 2-arylpyridines reacted with aromatic/aliphatic α-diketones.
- Zhou, Wei,Li, Hongji,Wang, Lei
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p. 4594 - 4597
(2012/10/29)
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- Palladium-catalyzed oxidative sp2 C-H bond acylation with aldehydes
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An efficient method was developed for the direct acylation of arene sp 2 C-H bonds with aldehydes using palladium acetate as catalyst and peroxide as oxidant. The solvent-free oxidative acylation reaction assisted by a pyridine directing group provides an easy access to aromatic, aliphatic, and optical active ketones.
- Basle, Olivier,Bidange, Johan,Shuai, Qi,Li, Chao-Jun
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supporting information; experimental part
p. 1145 - 1149
(2010/06/20)
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