- Reactions of bisdiazonium salts derived from monosubstituted m-phenylenediamines with amides and nitriles of unsaturated acids under anionarylation conditions
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Reactions of 5-carboxy and 4-methylphenylene-1,3-bisdiazonium tetrafluoroborates with amides and nitriles of acrylic and methacrylic acids in the presence of chloride, bromide, and thiocyanate anions proceed as anionarylation at one of the diazo groups and nucleophilic substitution at another one. With 4-methylphenylene- 1,3-bisdiazonium tetrafluoroborate as the arylating agent, the anionarylation and the Sandmeyer reaction occur involving para- and ortho-positioned diazo groups, respectively.
- Baranovskii,Yatsyuk,Vasilenko,Grishchuk
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- The lid domain of the MCP hydrolase DxnB2 contributes to the reactivity toward recalcitrant PCB metabolites
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DxnB2 and BphD are meta-cleavage product (MCP) hydrolases that catalyze C-C bond hydrolysis of the biphenyl metabolite 2-hydroxy-6-oxo-6-phenylhexa-2,4- dienoic acid (HOPDA). BphD is a bottleneck in the bacterial degradation of polychlorinated biphenyls (PCBs) by the Bph catabolic pathway due in part to inhibition by 3-Cl HOPDAs. By contrast, DxnB2 from Sphingomonas wittichii RW1 catalyzes the hydrolysis of 3-Cl HOPDAs more efficiently. X-ray crystallographic studies of the catalytically inactive S105A variant of DxnB2 complexed with 3-Cl HOPDA revealed a binding mode in which C1 through C6 of the dienoate are coplanar. The chlorine substituent is accommodated by a hydrophobic pocket that is larger than the homologous site in BphDLB400 from Burkholderia xenovorans LB400. The planar binding mode observed in the crystalline complex was consistent with the hyper- and hypsochromically shifted absorption spectra of 3-Cl and 3,9,11-triCl HOPDA, respectively, bound to S105A in solution. Moreover, ESred, an intermediate possessing a bathochromically shifted spectrum observed in the turnover of HOPDA, was not detected, suggesting that substrate destabilization was rate-limiting in the turnover of these PCB metabolites. Interestingly, electron density for the first α-helix of the lid domain was poorly defined in the dimeric DxnB2 structures, unlike in the tetrameric BphDLB400. Structural comparison of MCP hydrolases identified the NC-loop, connecting the lid to the α/β-hydrolase core domain, as a determinant in the oligomeric state and suggests its involvement in catalysis. Finally, an increased mobility of the DxnB2 lid may contribute to the enzyme's ability to hydrolyze PCB metabolites, highlighting how lid architecture contributes to substrate specificity in α/β-hydrolases.
- Ruzzini, Antonio C.,Bhowmik, Shiva,Yam, Katherine C.,Ghosh, Subhangi,Bolin, Jeffrey T.,Eltis, Lindsay D.
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- Photo-induced deep aerobic oxidation of alkyl aromatics
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Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry. Presently, the industrial manufacture of benzoic acids and benzene polycarboxylic acids (BPCAs) is mainly based on the deep oxidation of polyalkyl benzene, which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting MeBr and corrosion hazards of production equipment. In this report, photo-induced deep aerobic oxidation of (poly)alkyl benzene to benzene (poly)carboxylic acids was developed. CeCl3 was proved to be an efficient HAT (hydrogen atom transfer) catalyst in the presence of alcohol as both hydrogen and electron shuttle. Dioxygen (O2) was found as a sole terminal oxidant. In most cases, pure products were easily isolated by simple filtration, implying large-scale implementation advantages. The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks. [Figure not available: see fulltext.].
- Wang, Chang-Cheng,Zhang, Guo-Xiang,Zuo, Zhi-Wei,Zeng, Rong,Zhai, Dan-Dan,Liu, Feng,Shi, Zhang-Jie
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p. 1487 - 1492
(2021/07/10)
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- Synthesis of Dichlorobenzamide Derivatives: Crystal Structures of 3,5-Dichloro-N-(2-chlorophenyl)benzamide and 3,5-Dichloro-N-(4-chlorophenyl)benzamide
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Abstract: Reactions of 3,5-dichlorobenzoyl chloride and arylamine compounds in N,N′-dimethylformamidesolution at 60 °C afforded a series of dichlorobenzamidederivatives 4–14 in good yields. These new compounds and accompanyingintermediates were characterized and confirmed by nuclear magneticresonance and infrared spectroscopy, of which structures of compounds 4and 6 were established by X-ray crystallography. Compound 4 crystallizesin triclinic space group Pī, with a = 5.047 (18), b = 10.28 (4), c = 13.36 (5) ?, α =107.59 (5)°, β = 93.55 (5)°, γ = 98.34 (5)°, and Z = 2. The unit cell of 6 has a monoclinic Pn symmetry with the cell parameters a = 9.581 (3), b = 12.217 (4), c = 11.072 (3) ?, β = 92.584 (4)°, and Z = 4. Graphic Abstract: A series of 3,5-dichlorobenzamide compounds were synthesized from reactions of arylamine compounds with 3,5-dichlorobenzoyl chloride, which was prepared from 3,5-dichlorobenzonitrile.[Figure not available: see fulltext.]
- Zhang, Jun,Li, Yue,Wang, Bei,Jia, Ai-Quan,Zhang, Qian-Feng
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p. 108 - 115
(2020/02/18)
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- Milled Dry Ice as a C1 Source for the Carboxylation of Aryl Halides
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The use of carbon dioxide as a C1 chemical feedstock remains an active field of research. Here we showcase the use of milled dry ice as a method to promote the availability of CO 2in a reaction solution, permitting practical synthesis of arylcarboxylic acids. Notably, the use of milled dry ice produces marked increases in yields relative to those obtained with gaseous CO 2, as previously reported in the literature.
- O'Brien, Connor J.,Nicewicz, David A.
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supporting information
p. 814 - 816
(2021/03/01)
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- Dimethyl sulfoxide-accelerated reductive deamination of aromatic amines with t-BuONO in tetrahydrofuran
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An efficient method for the conversion of aryl amines into arenes by a one-pot reductive deamination has been achieved. It was found the reductive deamination using t-BuONO in tetrahydrofuran could be accelerated by dimethyl sulfoxide and provided the deamination products with good yields under mild conditions. A plausible mechanism is discussed.
- Fang, Lu,Qi, Liang,Ye, Longfei,Pan, Zhentao,Luo, Wenjun,Ling, Fei,Zhong, Weihui
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p. 579 - 583
(2018/11/27)
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- Synthesis method of 2-amino-5-chloro-N,3-dimethylbenzamide
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The invention discloses a synthesis method of 2-amino-5-chloro-N,3-dimethylbenzamide, belonging to the technical field of organic chemical synthesis. The method comprises the following steps: carrying out oxidation under the catalytic actions of N-hydroxyphthalimide and cobalt acetylacetonate to generate benzoic acid, carrying out substitution reaction with chlorine gas to generate 3,5-dichlorobenzoic acid, shielding off 5- chlorine by using a shielding reagent, carrying out methyl substitution on the 5- chlorine by using a Grignard reagent to generate 3-methyl-5-chlorobenzoic acid, carrying out nitro-substitution on the 3-methyl-5-chlorobenzoic acid and nitric acid under the catalytic action of concentrated sulfuric acid to generate 2-nitro-3-methyl-5-chlorobenzoic acid, carrying out catalytic hydrogenation to reduce the nitro group into amino group, carrying out reaction under the actions of N,N'-diisopropylcarbodiimide and 1-hydroxybenztriazole to obtain an intermediate, and carrying out reaction on the intermediate and methylamine to obtain the 2-amino-5-chloro-N,3-dimethylbenzamide. The method is simple to operate, and obviously enhances the synthesis yield to 92% or above.
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- Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
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Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
- Matic, Mirela,Denegri, Bernard,Kronja, Olga
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supporting information
p. 8986 - 8998,13
(2012/12/12)
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- SPIRO ISOXAZOLINE COMPOUNDS AS SSTR5 ANTAGONISTS
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Substituted spirocyclic amines of structural formula (I) are selective antagonists of the somatostatin subtype receptor 5 (SSTR5) and are useful for the treatment, control or prevention of disorders responsive to antagonism of SSTR5, such as Type 2 diabetes, insulin resistance, lipid disorders, obesity, atherosclerosis, Metabolic Syndrome, depression, and anxiety.
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Page/Page column 73; 74
(2011/12/04)
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- Selective Mg insertion into substituted mono- and dichloro arenes in the presence of LiCl: A new preparation of boscalid
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The LiCl-mediated Mg insertion into polysubstituted aryl chlorides bearing up to three chloro substituents in ortho or meta position selectively leads to Grignard reagents which readily react with various electrophiles. As an application, we have developed a new formal synthesis of boscalid. Georg Thieme Verlag Stuttgart - New York.
- Dunst, Cora,Knochel, Paul
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experimental part
p. 2064 - 2068
(2011/10/09)
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- Proton transfer equilibria between disubstituted benzoic acids and carbinol base of crystal violet in apolar aprotic solvents. Chemometric analysis of disubstituent effects on the strength of benzoic acid in chlorobenzene
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Proton transfer equilibria in chlorobenzene between a set of di-substituted (2,3-,2,5-,2,6-, 3,5-dichloro and difluoro) benzoic acids including the corresponding mono-substituted acids and the carbinol base of crystal violet have been studied spectrophotometrically. To investigate the effect of disubstitution at ortho- and/or meta- positions on the strength of benzoic acid, the results have been analysed chemometrically on the basis of Fujita Nishioka's multiparameter approach and the assumption of additivity for substituent effects. The model employed explains 94% of the variance for the disubstituent effects on log K. It is observed that the substituent effect is contributed by ordinary electronic and proximity electronic effects in an almost equal ratio (52:48).
- Sen Gupta, Susanta K.,Shrivastava, Ruchi
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p. 369 - 373
(2008/09/19)
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- Buttressing Effects Rerouting the Deprotonation and Functionalization of 1,3-Dichloro- and 1,3-Dibromobenzene
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A systematic comparison between 1,3-difluorobenzene, 1,3-dichlorobenzene, and 1,3-dibromobenzene did not reveal major differences in their behavior towards strong bases such as lithium diisopropylamide or lithium 2,2,6,6-tetramethyl-piperidide. Thus, all 2,6-dihalobenzoic acids 1 are directly accessible by consecutive treatment with a suitable base and dry ice. In contrast, (2,6-dichlorophenyl)- and (2,6-bromo-phenyl)triethylsilane (2a and 2b) were found to undergo deprotonation at the 5-position (affording acids 3 and, after deprotection, 4), whereas the 1,3-difluoro analog is known to react at the 4-position. The 2,4-dihalobenzoic acids 7 were selectively prepared from either the silanes 2 (by bromination at the 4-position, metalation and carboxylation of the neighboring position, followed by desilylation and debromination) or the 1,3-dihalo-2-iodobenzenes 8 (by base-promoted migration of iodine to the 4-position followed by iodine/magnesium permutation and subsequent carboxylation). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Heiss, Christophe,Marzi, Elena,Schlosser, Manfred
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p. 4625 - 4629
(2007/10/03)
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- Rat hepatic microsomal aldehyde dehydrogenase. Identification of 3- and 4-substituted aromatic aldehydes as substrates of the enzyme
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The rat hepatic microsomal aldehyde dehydrogenase (mALDH) metabolizes aliphatic and aromatic aldehydes to the corresponding acids with NAD as the optimal cofactor. However, dehydrogenation of the aliphatic compounds is substantially more efficient. In the present study, a series of aromatic aldehydes was evaluated as substrates of the purified mALDH so that the physicochemical factors that contribute to substrate affinity could be evaluated. Substitution of the aromatic system in the 3- and 4-positions produced relatively good substrates, but 2-substituted congeners did not undergo dehydrogenation. However, aldehydes with hydrophilic substituents in the 3- or 4-positions and those with extremely bulky substituents at both positions (e.g., 3,4-dibenzyloxy) were also poor substrates for the enzyme and dehydrogenation was undetectable. A quantitative structure-activity relationship was determined that related the logarithm of the Michaelis constants for 27 substituted aromatic aldehydes with the zero-order connectivity function of the molecule (0χ), the shapes of the 3-and 4-substituents (κ), and the electronic nature of the 4-substituent (σ). In this equation, 81% of the data variance was explained. From a consideration of the dimensions of 3-phenoxybenzaldehyde, which was a relatively good substrate, the mALDH possesses a narrow cleft within the active site that is at least 7.5 A wide and extends at least 12 A from the the catalytic residue (probably cysteine). Previously established relationships between connectivity functions and molecular polarizability suggest that dipolar interactions within the active site, as well as dispersion forces, may play a role in substrate specificity. Although optimal shapes for carbocyclic substituents were not provided by the analysis, the unfavorable effect on dehydrogenation from hydrophilic and large substituents suggests that the active site of the mALDH is relatively rigid and that the orientation of the substrate in relation to the catalytic cysteine and the cofactor binding site is critical.
- Martini, Robert,Murray, Michael
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p. 268 - 276
(2007/10/03)
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- Electrosynthesis of aryl-carboxylic acids from chlorobenzene derivatives and carbon dioxide
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The electrocarboxylation of a large variety of chlorobenzenic compounds is achieved in N,N-dimethylformamide by constant current electrolysis between a stainless steel cathode and a sacrificial magnesium anode in a diaphragmless cell. Substituted benzoic acids are obtained in high yield in simle conditions thus avoiding the usual preparation of organometallic intermediates.
- Heintz, Monique,Sock, Oumar,Saboureau, Christophe,Perichon, Jacques,Troupel, Michel
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p. 1631 - 1636
(2007/10/02)
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- Manufacture of substituted halobenzenes
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Halobenzenes are manufactured by (a) a one-vessel reaction of anilines with halogenating agents to give haloanilines, followed by reaction of the mixture thus obtained with alkanols and nitrosylating agents in the presence of water and acid at not less than 35° C. or (b) the corresponding reaction of a haloaniline which has been manufactured in the above manner or by some other method and has been isolated from its reaction mixture. The products are starting materials for the manufacture of drugs, dyes and pesticides.
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- Process for the production of dichlorobenzoic acids
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The production of dichlorobenzoic acids by reaction of the diazonium compound of a dichloroaminobenzoic acid with an aqueous alcohol solution of specific concentration. The compounds which can be prepared according to the process of the invention are valuable starting materials for the production of pharmaceutical substances, dyes and pesticides.
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