- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
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The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
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- Selective and Additive-Free Hydrogenation of Nitroarenes Mediated by a DMSO-Tagged Molecular Cobalt Corrole Catalyst
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We report on the first cobalt corrole that effectively mediates the homogeneous hydrogenation of structurally diverse nitroarenes to afford the corresponding amines. The given catalyst is easily assembled prior to use from 4-tert-butylbenzaldehyde and pyrrole followed by metalation of the resulting corrole macrocycle with cobalt(II) acetate. The thus-prepared complex is self-contained in that the hydrogenation protocol is free from the requirement for adding any auxiliary reagent to elicit the catalytic activity of the applied metal complex. Moreover, a containment system is not required for the assembly of the hydrogenation reaction set-up as both the autoclave and the reaction vessels are readily charged under a regular laboratory atmosphere.
- Sch?fberger, Wolfgang,Timelthaler, Daniel,Topf, Christoph
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supporting information
p. 2114 - 2120
(2021/07/22)
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- High graphite N content in nitrogen-doped graphene as an efficient metal-free catalyst for reduction of nitroarenes in water
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Four kinds of nitrogen-doped graphene (NG) as metal-free catalysts are synthesized by a one-step hydrothermal reaction and thermal treatment using graphene oxide and urea as precursors. It is found that the reduction of nitroarenes can be catalyzed by using a low NG loading and a small amount of NaBH4 in water with high yield. The type of nitrogen species in NG has an important effect on the reduction reaction. The NG catalyst containing the most graphite N shows the highest catalytic activity during reduction of nitroarenes, which demonstrates that the graphite N of NG plays a key role in impelling this reaction. The reaction mechanism is proven by GC-MS experiments, and DFT calculations reveal the reasons for the graphite N showing better catalytic activity. It is worth noting that no dehalogenation phenomenon occurs during the reduction process for halogen-substituted nitroarenes in contrast to conventional metal catalysts. In addition, the NG catalyst can be simply recycled and efficiently used for eight consecutive runs with no significant decrease in activity.
- Yang, Fan,Chi, Cheng,Wang, Chunxia,Wang, Ying,Li, Yongfeng
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supporting information
p. 4254 - 4262
(2016/08/02)
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- The ortho effect on the acidic and alkaline hydrolysis of substituted formanilides
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The kinetics of formanilides hydrolysis were determined under first-order conditions in hydrochloric acid (0.01-8 M, 20-60°C) and in hydroxide solutions (0.01-3 M, 25 and 40°C). Under acidic conditions, second-order specific acid catalytic constants were used to construct Hammett plots. The ortho effect was analyzed using the Fujita-Nishioka method. In alkaline solutions, hydrolysis displayed both first- and second-order dependence in the hydroxide concentration. The specific base catalytic constants were used to construct Hammett plots. Ortho effects were evaluated for the first-order dependence on the hydroxide concentration. Formanilide hydrolyzes in acidic solutions by specific acid catalysis, and the kinetic study results were consistent with the AAC2 mechanism. Ortho substitution led to a decrease in the rates of reaction due to steric inhibition of resonance, retardation due to steric bulk, and through space interactions. The primary hydrolytic pathway in alkaline solutions was consistent with a modified BAC2 mechanism. The Hammett plots for hydrolysis of meta- and para-substituted formanilides in 0.10 M sodium hydroxide solutions did not show substituent effects; however, ortho substitution led to a decrease in rate constants proportional to the steric bulk of the substituent.
- Desai, Salil Dileep,Kirsch, Lee E.
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p. 471 - 488
(2015/06/30)
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- A facile and efficient method for the selective deacylation of N-arylacetamides and 2-chloro-Narylacetamides catalyzed by SOCl2
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Thionyl chloride efficiently and selectively promoted the deacylation of N-arylacetamides and 2-chloro-N-arylacetamides, under anhydrous conditions, without effecting the ester group, aminosulfonyl group, or benzyloxyamide group. This method, which has been successfully applied to a variety of substrates including different N-arylacetamides and 2-chloro-N-arylacetamides, has the attractive advantages of inexpensive reagents, satisfactory selectivity, excellent yields, short reaction time, and convenient workup. This new method can probably be used to selectively deacylate between aromatic amides and alkyl amides. Springer Science+Business Media B.V. 2011.
- Wang, Gong-Bao,Wang, Lin-Fa,Li, Chao-Zhang,Sun, Jing,Zhou, Guang-Ming,Yang, Da-Cheng
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- Weak halogen bonding in solid haloanilinium halides probed directly via chlorine-35, bromine-81, and iodine-127 NMR spectroscopy
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A series of monohaloanilinium halides exhibiting weak halogen bonding (XB) has been prepared and characterized by 35Cl, 81Br, and 127I solid-state nuclear magnetic resonance (SSNMR) spectroscopy in magnetic fields of up to 21.1 T. The quadrupolar and chemical shift (CS) tensor parameters for halide ions (Cl-, Br-, I-) which act as electron density donors in the halogen bonds of these compounds are measured to provide insight into the possible relationship between halogen bonding and NMR observables. The NMR data for certain series of related compounds are strongly indicative of when such compounds pack in the same space group, thus providing practical structural information. Careful interpretation of the NMR data in the context of novel and previously available X-ray crystallographic data, and new gauge-including projector-augmented-wave density functional theory (GIPAW DFT) calculations has revealed several notable trends. When a series of related compounds pack in the same space group, it has been possible to interpret trends in the NMR data in terms of the strength of the halogen bond. For example, in isostructural series, the halide quadrupolar coupling constant was found to increase as the halogen bond weakens. In the case of a series of haloanilinium bromides, the 81Br isotropic chemical shift and CS tensor span both decrease as the bromide-halogen XB is weakened. These trends were reproduced using both GIPAW DFT and cluster-model calculations of the bromide ion magnetic shielding tensor. Such trends are particularly exciting given the well-known role that NMR has played historically in the characterization of hydrogen bonding.
- Attrell, Robert J.,Widdifield, Cory M.,Korobkov, Ilia,Bryce, David L.
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experimental part
p. 1641 - 1653
(2012/06/30)
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- Alternative method for the reduction of aromatic nitro to amine using TMDS-iron catalyst system
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The system 1,1,3,3-tetramethyldisiloxane (TMDS)/Fe(acac)3 is reported here as a new method to obtain amines from aromatic nitro compounds. Amines are synthetized in a straightforward step and are isolated as hydrochloride salts with good to excellent yields. This system has shown a good selectivity toward aryl-chloride, aryl-bromide, ester, carboxylic acid, and cyano groups. The reduction of alkylnitro compounds was unfortunately not possible using this method, only a mixture of mono and dialkylated amine was obtained.
- Pehlivan, Leyla,Métay, Estelle,Laval, Stéphane,Dayoub, Wissam,Demonchaux, Patrice,Mignani, Gérard,Lemaire, Marc
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experimental part
p. 1971 - 1976
(2011/04/22)
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- Highly chemo- and regioselective reduction of aromatic nitro compounds using the system silane/oxo-rhenium complexes
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(Chemical Equation Presented) The reduction of aromatic nitro compounds to the corresponding amines with silanes catalyzed by high valent oxo-rhenium complexes is reported. The catalytic systems PhMe2SiH/ReIO 2(PPh3)2 (5 mol %) and PhMe2SiH/ ReOCl3(PPh3)2 (5 mol %) reduced efficiently a series of aromatic nitro compounds in the presence of a wide range of functional groups such as ester, halo, amide, sulfone, lactone, and benzyl. This methodology also allowed the regioselective reduction of dinitrobenzenes to the corresponding nitroanilines and the reduction of an aromatic nitro group in presence of an aliphatic nitro group. 2009 American Chemical Society.
- De Noronha, Rita G.,Romao, Carlos C.,Fernandes, Ana C.
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supporting information; experimental part
p. 6960 - 6964
(2010/03/03)
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- Biguanide derivatives, manufacturing method thereof, and disinfectants containing the derivatives
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The invention presents a biguanide derivative or its salt expressed by a formula: STR1 (where R1 and R2 are as defined in Specification), or formula: STR2 (where A and R3 is as defined in specification). This biguanide derivative or its salt is preferably used as the effective amount of a disinfectant for humans, animals, medical appliances, etc.
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