- Unexpected side products in the tetramethylammonium fluoride-dimethylsulphoxide system
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Reactions of chloro- and nitro-aromatics with low water content solutions of TMAF in DMSO can lead to complex product mixtures resulting from activation of DMSO by fluoride and the formation of DMSO-derived products. Also, the system has been shown to give hydrolysis products in addition to the well-known ethers and phenols, with carboxylic acids and benzamides being formed from the attempted fluorodenitration of substituted benzonitriles.
- Adams, Dave J.,Clark, James H.,McFarland, Heather,Nightingale, David J.
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- The effect of basicity on fluorodenitration reactions using tetramethylammonium salts
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The fluorodenitration of several nitroaromatics with tetramethylammonium salts has been found to be dependent on the basicity of the fluorinating species. Tetramethylammonium fluoride is highly basic and is capable of inducing H-D exchange in 1,3-dinitrobenzene, as well as deprotonating N,N- dimethylacetamide. Reaction of the fluoride with phthalic anhydride forms the bifluoride in situ. Tetramethylammonium bifluoride gives higher yields of the required fluoroaromatic, but slower reaction rates than the corresponding fluoride.
- Adams, Dave J.,Clark, James H.,Nightingale, David J.
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- Preparation and characterization of a novel silica-KF composite and facile fluorination of aromatic substrates
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A novel silica-KF reagent prepared by hydrolyzing tetraethyl orthosilicate in the presence of KF for fluorination of activated aromatic compounds has been reported. The reagent, as characterized by techniques such as SEM-EDX, XRD and IR spectroscopy, is shown to have potassium cations entrapped inside the silica matrix whereas fluoride anions remain on the surface. Reaction of activated chlorinated aromatic substrates with this silica-KF leads to formation of Meisenheimer complex, either in situ or isolable, finally resulting in regioselective fluorinated aromatics.
- Patel, Sagar S.,Bochare, Machhindra D.,Degani, Mariam S.
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- Tetramethylammonium hydrogendifluoride: A convenient source of nucleophilic fluoride
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Tetramethylammonium hydrogendifluoride (TMAHF2) acts as an effective fluoride source for the selective fluorination in high yields of various chloro and nitroaromatics via halogen exchange (halex) and fluorodenitration.
- Adams, David J.,Clark, James H.,Nightingale, David J.
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- Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
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Acting as in situ sources of triflyl nitrate (TfONO2) and trifluoroacetyl nitrate (CF3COONO2), the EAN/Tf 2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K T/KB = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 8088 - 8094
(2011/11/13)
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- Propylphosphonic anhydride (T3P): A remarkably efficient reagent for the one-pot transformation of aromatic, heteroaromatic, and aliphatic aldehydes to nitriles
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Propylphosphonic anhydride has been demonstrated to be an efficient reagent for the transformation of aromatic, heteroaromatic, and aliphatic aldehydes to respective nitriles in excellent yields. This procedure offers simple and one-pot access to nitriles and highlights the synthetic utility of T3P as a versatile reagent in organic chemistry. Georg Thieme Verlag Stuttgart - New York.
- Augustine, John Kallikat,Atta, Rajendra Nath,Ramappa, Balakrishna Kolathur,Boodappa, Chandrakantha
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experimental part
p. 3378 - 3382
(2010/03/03)
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- IMIDAZOLE COMPOUNDS AND THEIR USE AS CALCIUM CHANNEL BLOCKERS
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The present invention discloses compounds of the formula STR1 wherein X is C;Y is C;R 4 to R. sup.7 and R 11 to R 13 are as defined herein; or a pharmaceutically-acceptable addition salt thereof. The compounds are useful as pharmaceuticals, fo
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- Imidazole compounds, their preparation and use
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The present invention discloses compounds of the formula wherein, X is C or N;, Y is C or N;, R11 is hydrogen, hydroxy, or alkoxy;, R12 and R13 are each independently hydrogen; halogen; CF3; CN; OH; alkyl; cycloalkyl; cycloalkylalkyl; alkenyl;
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- A convenient and new modified preparation of nitrosubstituted aryl fluorides
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Nitrosubstituted aryl fluorides are easily prepared in good yields from chloro-nitrobenzenes and potassium fluoride in dimethyl sulfoxide and in the presence of polyethylene glycol 5090.
- Deutsch,Niclas
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p. 505 - 513
(2007/10/02)
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