- Aluminum oxide mediated C-F bond activation in trifluoromethylated arenes
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Thermally activated γ-aluminium oxide was found to be very effective for C-F bond activation in trifluoromethylated arenes. Depending on the activation degree the respective arenes can be converted either to cyclic ketones or to the respective carboxylic acids with good to excellent yields.
- Papaianina,Amsharov
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- Hypervalent iodine in synthesis XL: First example of palladium-catalyzed coupling reaction of 1-hydroxy-1,2-benziodoxol-3(1H)-one with arylboronic acids and arylborates
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Biaryl-2-carboxylic acids have been prepared by palladium-catalyzed coupling reaction of 1-hydroxy-1,2-benziodoxol-3(1H)-one with arylboronic acids and arylborates with good yields under mild conditions.
- Xia, Min,Chen, Zhenchu
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- Room-temperature cobalt-catalyzed arylation of aromatic acids: overriding the ortho-selectivity via the oxidative assembly of carboxylate and aryl titanate reagents using oxygen
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A room temperature phosphine or NHC ligand-free cobalt-catalyzed arylation of (hetero)aromatic acids has been developed. It involves an oxidative cross-coupling between carboxylate and aryl titanate reagents using oxygen as an oxidant, and the arylation at the position ortho, meta and para to the carboxylic acid group could all be achieved. As application, various (hetero)aromatic acids including xenalipin, tafamidis and the key intermediate for a cardioprotective compound have been efficiently synthesized.
- Liu, Kun-Ming,Zhang, Rui,Duan, Xin-Fang
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- Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols
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Relative rates for the Lewis base-mediated acylation of secondary and primary alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydride derivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate size leads to an actual acceleration of the acylation process, the effect being larger for secondary as compared to primary alcohols. Computational results indicate that acylation rates are guided by noncovalent interactions (NCIs) between the catalyst ring system and the DED substituents in the alcohol and anhydride reactants. Thereby stronger NCIs are formed for secondary alcohols than for primary alcohols.
- Mayr, Stefanie,Marin-Luna, Marta,Zipse, Hendrik
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p. 3456 - 3489
(2021/03/01)
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- Synthesis of seven-membered lactones by regioselective and stereoselective iodolactonization of electron-deficient olefins
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A regio- A nd stereoselective iodolactonization of internal electron-deficient olefinic acids has been reported, which provides a straightforward access to a series of multi-functionalized seven-membered lactones containing two consecutive chiral centers. The ester substituents on the olefins played a key role in achieving high regioselectivity. This result was proved through experiments and DFT calculations.
- Ke, Zhuofeng,Li, Ming,Liu, Yue-Jin,Luo, Xiao-Peng,Shao, You-Xiang,Tang, Pan-Ting,Wang, Liang-Neng,Wei, Yi,Zeng, Ming-Hua,Zhang, Ni-Juan
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p. 6680 - 6683
(2020/07/03)
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- Visible-Light-Induced Arene C(sp 2)-H Lactonization Promoted by DDQ and tert -Butyl Nitrite
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A visible-light photocatalytic aerobic oxidative lactonization of arene C(sp 2)-H bonds proceeds in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tert -butyl nitrite (TBN). Under the optimized conditions, a range of 2-arylbenzoic acids is converted into the corresponding benzocoumarin derivatives in moderate to excellent yields. This method is characterized by its atom economy, mild reaction conditions, the use of a green oxidant and metal-free catalysis.
- Chen, Bajin,Hu, Baoxiang,Hu, Xinquan,Jin, Liqun,Li, Meichao,Shen, Zhenlu,Sun, Nan,Wang, Shengpeng,Wang, Yiqing
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p. 261 - 266
(2020/02/18)
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- Exploration of Biaryl Carboxylic Acids as Proton Shuttles for the Selective Functionalization of Indole C-H Bonds
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A survey of diversely substituted 2-arylbenzoic acids were synthesized and tested for use as proton shuttle in the direct arylation of indoles with bromobenzenes. It was found that 3-ethoxy-2-phenylbenzoic acid gives superior yield and selectivity for this class of substrates.
- Pi, Jing-Jing,Lu, Xiao-Yu,Liu, Jing-Hui,Lu, Xi,Xiao, Bin,Fu, Yao,Guimond, Nicolas
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p. 5791 - 5800
(2018/05/14)
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- Differentially Substituted Phosphines via Decarbonylation of Acylphosphines
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A new route to phosphines was developed by a method that features a "pre-join and transform" process that proceeds via acylphosphine intermediates that may be readily prepared from carboxylic acids and disubstituted phosphines. The efficient decarbonylations of these acylphosphines using a nickel catalyst delivered the corresponding phosphines. This method shows that the carboxyl group can play a role similar to halides or triflates for introducing a substituted phosphorus atom on an aromatic ring.
- Yu, Rongrong,Chen, Xingyu,Martin, Stephen F.,Wang, Zhiqian
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p. 1808 - 1811
(2017/04/11)
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- Synthesis of fluorenones through rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids
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An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones.
- Fukuyama, Takahide,Maetani, Shinji,Miyagawa, Kazusa,Ryu, Ilhyong
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p. 3216 - 3219
(2014/07/08)
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- Palladium-catalyzed intermolecular decarboxylative coupling of 2-phenylbenzoic acids with alkynes via C-H and C-C bond activation
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A novel protocol for palladium-catalyzed intermolecular formal [4 + 2] annulation of 2-phenylbenzoic acids with alkynes is described. Acridine is shown to be essential for the high reaction efficiency. Phenanthrene derivatives are formed in moderate to good yields without coupling (pseudo)halides or organometallic species.
- Wang, Congyang,Rakshit, Souvik,Glorius, Frank
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supporting information; experimental part
p. 14006 - 14008
(2010/12/24)
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- Transmission of Polar Effects. Part 20. Ionisation and Esterification, with Diazodiphenylmethane, of a Series of 8-(2-Substituted Phenyl)-1-naphthoic and 2- and 4-(8-Substituted 1-Naphthyl)benzoic acids
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The pKa-values of a series of 8-(2-substituted phenyl)-1-naphthoic and 2- and 4-(8-substituted 1-naphthyl)benzoic acids have been determined in 80percent (w/w) 2-methoxyethanol-water at 25 deg C.The rate coefficients for the esterification of t
- Bowden, Keith,Ghadir, Khalaf D. F.
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p. 1329 - 1332
(2007/10/02)
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