- High Yields of Nitrene Insertion into Unactivated C-H Bonds. First Example of X-Ray Crystallographic and 19F NMR Analysis of the Photochemically Produced C-H Inserted Adduct
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Photolysis of 4-azido-tetrafluorobenzonitrile results in the highest yield reported to date, (75 - 80percent as estimated from 19F NMR spectroscopy) for nitrene insertion into the unactivated C-H bond of cyclohexane; the photochemical adduct is characteri
- Pandurangi, Raghoottama S.,Katti, Kattesh V.,Barnes, Charles L.,Volkert, Wynn A.,Kuntz, Robert R.
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- Photosensitizer probe TFDB as well as preparation method and application thereof
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The invention discloses a photosensitizer probe TFDB as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving pentafluorobenzonitrile in a solvent, stirring for reaction, dropwise adding amm
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Paragraph 0031-0032; 0041-0042; 0053-0054
(2020/09/12)
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- Synthetic method of 2,3,5,6-tetrafluoroaniline
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The invention relates to a synthetic method of aniline, in particular to a synthetic method of 2,3,5,6-tetrafluoroaniline. The synthetic method comprises the following steps: taking 2,3,4,5,6-pentafluorobenzonitrile as a raw material; carrying out ammonification on the 2,3,4,5,6-pentafluorobenzonitrile with ammonia water at first; carrying out aftertreatment to obtain an intermediate which is 4-amino-2,3,5,6-tetrafluoroaniline; adding 90% of sulfuric acid; and carrying out hydrolyzing and decarboxylation to generate the 2,3,5,6-tetrafluoroaniline. The ammonia water is an aminating agent, ethylacetate is used as a solvent, tetrabutylammonium hydrogen sulphate is used as a phase transfer catalyst, high-selection ammoniation is carried out at low temperature, thus, an isomer by-product whichis 2-amino-3,4,5,6- tetrafluorobenzonitrile generated by general ammoniation is avoided, the high-purity intermediate which is 4-amino-2,3,5,6-tetrafluoroaniline can be obtained directly, and the purity of the 4-amino-2,3,5,6-tetrafluoroaniline can be 99.5% or above.
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Paragraph 0024-0025; 0027-0028
(2018/04/27)
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- Hydrogen Bond Directed Photocatalytic Hydrodefluorination: Overcoming Electronic Control
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The photocatalytic C-F functionalization of highly fluorinated arenes is a powerful method for accessing functionalized multifluorinated arenes. The decisive step in the determining regioselectivity in fluorine functionalization is fluoride fragmentation from the radical anion of the multifluorinated arene. To date, the availability of regioisomers has been dictated by the innate electronics of the fluorinated arene, limiting the synthetic utility of the chemistry. This study investigates the remarkable ability of a strategically located hydrogen bond to transcend the normal regioselectivity of the C-F functionalization event. A significant rate acceleration is additionally observed for hydrodefluorination of fluorines that can undergo intramolecular hydrogen bonds that form 5-8-membered cycles with moderately acidic N-H's. The hydrogen bond is expected to facilitate the fragmentation not only by bending the C-F bond of the radical anion out of planarity but also by increasing the exothermicity of the fluoride extrusion step through protonation of the naked fluoride. Finally, the synthetic utility of the method is demonstrated in an expedited synthesis of the trifluorinated α-phenyl acetic acid derivative required for the commercial synthesis of Januvia, an antidiabetic drug. This represents the first synthesis of a commercially important multifluorinated arene via a defluorination strategy and is significantly shorter than the current strategy.
- Khaled, Mohammad B.,El Mokadem, Roukaya K.,Weaver, Jimmie D.
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supporting information
p. 13092 - 13101
(2017/09/26)
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- Pd(II)-catalyzed enantioselective synthesis of P-stereogenic phosphinamides via desymmetric C-H arylation
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We present the enantioselective synthesis of P-stereogenic phosphinamides through Pd-catalyzed desymmetric ortho C-H arylation of diarylphosphinamides with boronic esters. The method represents the first example of the synthesis of P-stereogenic phosphorus compounds via the desymmetric C-H functionalization strategy. The reaction proceeded efficiently with a wide array of reaction partners to afford the P-stereogenic phosphinamides in up to 74% yield and 98% ee. The efficiency was further demonstrated by gram scale syntheses. Moreover, the flexible conversion of the P-stereogenic phosphinamides into various types of P-stereogenic phosphorus derivatives was also elaborated. Thus, the protocol provides a novel tool for the efficient and versatile synthesis of P-stereogenic compounds.
- Du, Zhi-Jun,Guan, Jing,Wu, Guo-Jie,Xu, Peng,Gao, Lian-Xun,Han, Fu-She
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supporting information
p. 632 - 635
(2015/01/30)
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- Photocatalytic hydrodefluorination: Facile access to partially fluorinated aromatics
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Polyfluorinated aromatics are essential to materials science as well as the pharmaceutical and agrochemical industries and yet are often difficult to access. This Communication describes a photocatalytic hydrodefluorination approach which begins with easily accessible perfluoroarenes and selectively reduces the C-F bonds. The method allows facile access to a number of partially fluorinated arenes and takes place with unprecedented catalytic activity using a safe and inexpensive amine as the reductant.
- Senaweera, Sameera M.,Singh, Anuradha,Weaver, Jimmie D.
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supporting information
p. 3002 - 3005
(2014/03/21)
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- Continuous flow synthesis of difluoroamine systems by direct fluorination
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Continuous flow methodology for the synthesis of perfluoroaryl difluoroamine derivatives by reaction of fluorine gas with an appropriate perfluoroaniline substrate is described, further demonstrating the efficient use of flow regimes for reactions involvi
- McPake, Christopher B.,Murray, Christopher B.,Sandford, Graham
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p. 145 - 150
(2013/04/10)
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- Pd(II)-catalyzed enantioselective C-H activation of cyclopropanes
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Systematic ligand development has led to the identification of novel mono-N-protected amino acid ligands for Pd(II)-catalyzed enantioselective C-H activation of cyclopropanes. A diverse range of organoboron reagents can be used as coupling partners, and the reaction proceeds under mild conditions. These results provide a new retrosynthetic disconnection for the construction of enantioenriched cis-substituted cyclopropanecarboxylic acids.
- Wasa, Masayuki,Engle, Keary M.,Lin, David W.,Yoo, Eun Jeong,Yu, Jin-Quan
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supporting information; experimental part
p. 19598 - 19601
(2012/01/17)
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- Mechanisms of reactions of halogenated compounds. Part 7. Effects of fluorine and other groups as substituents on nucleophilic aromatic substitution
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The effect of fluorine as a substituent group on nucleophilic aromatic substitution is discussed, where a fluorine atom located ortho to the point of substitution may be of variable activating influence, whereas fluorine located para is slightly deactivat
- Chambers, Richard D.,Martin, Peter A.,Sandford, Graham,Williams, D. Lyn H.
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scheme or table
p. 998 - 1002
(2009/04/04)
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- Method for production of aromatic compounds
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For the production of an aromatic compound by hydrolyzing and decarboxylating a corresponding aromatic cyano compound in the presence of an acidic substance, this invention provides a method for the production of the aromaic compound, characterized by car
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- Reactions of polyfluoroarenes with hexamethyldisilazane and with 1,1,1-trimethyl-N,N-bis(trimethylsilyl)stannaneamine in the presence of caesium fluoride
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Hexamethyldisilazane and 1,1,1-trimethyl-N,N-bis(trimethylsilyl)stannaneamine aminate pentafluoropyridine, octafluorotoluene, pentafluorobenzonitrile, pentafluoronitrobenzene and pentafluorobenzene sulphonyl fluoride in the presence of caesium fluoride with formation of the corresponding perfluorinated aryl amines (ArNH2), diarylamines (Ar2NH) and triarylamines (Ar3N) (where the amine functions are in positions 4 relative to the arene substituent). - Keywords: Polyfluoroarenes; Hexamethyldisilazane; Caesium fluoride; Silylated amines
- Miller, Alexey O.,Furin, Georgii G.
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p. 169 - 172
(2007/10/03)
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