- An environmentally benign benzylic oxidation catalyzed by hypervalent iodine intermediate in water
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An effective and environmentally benign benzylic oxidation for transition of alkylarenes into the corresponding carbonyl compounds was reported. Alkylarenes were mixed and stirred with potassium bromide, m-chloroperbenzoic acid and a catalytic amount of iodobenzene in water at 60 °C for several hours, a series of the corresponding carbonyl compounds was obtained in moderate to good yields. In the reaction, iodobenzene was first oxidized by m-chloroperbenzoic acid into the hypervalent iodine intermediate which then reacted with potassium bromide to form the key radical initiator for the benzylic oxidation.
- Xu, Yuan,Hu, Jian Tao,Yan, Jie
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- Photocatalyst-controlled and visible light-enabled selective oxidation of pyridinium salts
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This study proposes two different methods of photocatalytic-controlled and visible light-induced selective oxidation of pyridiniums with air as the terminal oxidant. The key to these transformations is to choose the appropriate light source and photocatal
- Peng, Xiang-Jun,He, Hai-Ping,Liu, Qian,She, Kun,Zhang, Bao-Qi,Wang, Heng-Shan,Tang, Hai-Tao,Pan, Ying-Ming
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p. 753 - 760
(2021/03/31)
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- Rapid formation of nitrogen-doped carbon foams by self-foaming as metal-free catalysts for selective oxidation of aromatic alkanes
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Porous carbon materials have attracted considerable interest as metal-free catalysts. In this study, we report a nitrogen-doped and nanofiber-based porous carbon foam produced via an efficient and facile self-foaming approach and its subsequent pyrolysis; in this approach, carbon dioxide-rich ethanolamine serves as the foaming agent, N source and polymerization catalyst. Meanwhile resorcinol and formaldehyde are used as carbon sources. Carbon dioxide-rich ethanolamine plays a crucial role in the release of gas as well as initiating polymerization on the interfaces of bubbles, which directs the formation of polymer foam. The N-doped carbon foam can be a highly active metal-free heterogeneous catalyst to promote selective oxidation of the benzyl group to the corresponding phenone. In addition, the carbon foams are easily cast with different morphologies. Notably, the prepared carbon foam is fabricated as a monolithic reactor for the oxidation reaction, which also exhibits good catalytic performances in the scale-up experiment.
- Qin, Guo-Xin,Hao, Yan,Wang, Shuai,Dong, Yu-Bin
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- Method for simply and conveniently synthesizing heterocyclic aryl ketone compound
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The invention discloses a method for simply and conveniently synthesizing a heterocyclic aryl ketone compound, and belongs to the technical field of the organic chemistry. The method comprises the following steps: using a benzyl heterocyclic compound as a reaction raw material, in a polar solvent, heating and reacting in an oxygen atmosphere, to obtain a multi-substituted ketone compound. The method is capable of using molecular oxygen as an oxidizing agent, green and environmental, and capable of preparing ketone by directly promoting selective oxidation and functionalization of a Csp3-H bond, and broadening a synthetic method for the ketone compound.
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Paragraph 0046; 0047; 0048; 0049; 0050; 0052
(2019/01/23)
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- An efficient approach for enhancing the catalytic activity of Ni-MOF-74: Via a relay catalyst system for the selective oxidation of benzylic C-H bonds under mild conditions
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Although nickel-based materials exhibit similar catalytic activity to palladium in organic synthesis, the selective oxidation of inert C-H bonds in the absence of other co-catalysts remains a largely unsolved challenge. This paper introduces a facile and efficient approach for enhancing the catalytic activity of Ni-MOF-74 with [bmim]Br via a relay catalysis strategy, which is excellent for the selective oxidation of benzylic C-H bonds. Notably, the catalyst recycling and scale up experiments demonstrated the practicability of the protocol. This method combines the catalytic advantages of MOFs and ionic liquids (ILs), and provides an insight into oxidation reactions by cheap and efficient Ni-based catalysts.
- Guo, Changyan,Zhang, Yonghong,Zhang, Yi,Wang, Jide
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supporting information
p. 3701 - 3704
(2018/04/17)
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- Copper-Catalyzed Aerobic Oxygenation of Benzylpyridine N-Oxides and Subsequent Post-Functionalization
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A copper-catalyzed aerobic oxidation of benzylpyridine N-oxides is reported. The N-oxide moiety acts as a built-in activator for the benzylic methylene oxidation, without requirement of additives. Reaction conditions were identified which suppress undesired benzoylpyridine formation via N-deoxygenation involving intermolecular oxygen transfer. The versatility of the N-oxide group of the benzoylpyridine N-oxide reaction products for post-functionalization of the pyridine ring is demonstrated through efficient C–C, C–N, C–O and C–Cl bond forming procedures, with both nucleophiles and electrophiles. Finally, the applicability of the new synthetic methodology is demonstrated in an alternative route towards the antihistaminic drug Acrivastine via three consecutive N-oxide activated C–H functionalization processes, starting from picoline N-oxide. (Figure presented.).
- Sterckx, Hans,Sambiagio, Carlo,Médran-Navarrete, Vincent,Maes, Bert U. W.
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supporting information
p. 3226 - 3236
(2017/09/13)
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- Efficient Selenium-Catalyzed Selective C(sp3)?H Oxidation of Benzylpyridines with Molecular Oxygen
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An efficient selenium-catalyzed direct oxidation of benzylpyridines in aqueous DMSO has been successfully developed by using molecular oxygen as the oxidant. A variety of benzoylpyridines with broad functional group tolerance were obtained in modest to excellent yields and with exclusive chemoselectivity. (Figure presented.).
- Jin, Weiwei,Zheng, Poonnapa,Wong, Wing-Tak,Law, Ga-Lai
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p. 1588 - 1593
(2017/05/05)
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- Base metal-catalyzed benzylic oxidation of (aryl)(heteroaryl)methanes with molecular oxygen
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The methylene group of various substituted 2- and 4-benzylpyridines, benzyldiazines and benzyl(iso)quinolines was successfully oxidized to the corresponding benzylic ketones using a copper or iron catalyst and molecular oxygen as the stoichiometric oxidant. Application of the protocol in API synthesis is exemplified by the alternative synthesis of a precursor to the antimalarial drug Mefloquine. The oxidation method can also be used to prepare metabolites of APIs which is illustrated for the natural product papaverine. ICP-MS analysis of the purified reaction products revealed that the base metal impurity was well below the regulatory limit.
- Sterckx, Hans,De Houwer, Johan,Mensch, Carl,Herrebout, Wouter,Tehrani, Kourosch Abbaspour,Maes, Bert U.W.
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supporting information
p. 144 - 153
(2016/04/05)
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- Synergistic H4NI-AcOH Catalyzed Oxidation of the Csp3-H Bonds of Benzylpyridines with Molecular Oxygen
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The oxidation of benzylpyridines forming benzoylpyridines was achieved based on a synergistic H4NI-AcOH catalyst and molecular oxygen in high yield under solvent-free conditions. This is the first nonmetallic catalytic system for this oxidation transformation using molecular oxygen as the oxidant. The catalytic system has a wide scope of substrates and excellent chemoselectivity, and this procedure can also be scaled up. The study of a preliminary reaction mechanism demonstrated that the oxidation of the Csp3-H bonds of benzylpyridines was promoted by the pyridinium salts formed by AcOH and benzylpyridines. The synergistic effect of H4NI-AcOH was also demonstrated by control experiments. (Figure Presented).
- Ren, Lanhui,Wang, Lianyue,Lv, Ying,Li, Guosong,Gao, Shuang
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supporting information
p. 2078 - 2081
(2015/05/13)
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- A new method for the benzylic oxidation of alkylarenes catalyzed by hypervalent iodine(III)
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A convenient and simple procedure is described for the oxidation of the benzylic C-H moiety of alkylarenes to give the corresponding aryl ketones, using tert-butyl hydroperoxide and m-chloroperoxybenzoic acid in the presence of a catalytic amount of the hypervalent iodine reagent, (diacetoxyiodo)benzene. The reactions typically occur in good yields in 2,2,2-trifluoroethanol as the solvent and at room temperature. Georg Thieme Verlag Stuttgart.New York.
- Xu, Yuan,Yang, Zhenping,Hu, Jiantao,Yan, Jie
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p. 370 - 374
(2013/03/13)
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- CARBOCATALYSTS FOR CHEMICAL TRANSFORMATIONS
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The disclosure relates to catalytically active carbocatalysts, e.g., a graphene oxide or graphite oxide catalyst suitable for use in a variety of chemical transformations. In one embodiment, it relates to a method of catalyzing a chemical reaction of an organic molecule by reacting the organic molecule in the presence of a sufficient amount of graphene oxide or graphite oxide for a time and at a temperature sufficient to allow catalysis of a chemical reaction. According to other embodiments, the reaction may be an oxidation reaction, a hydration reaction, a dehydrogenation reaction, a condensation reaction, or a polymerization reaction. Some reactions may include auto-tandem reactions. The disclosure further provides reaction mixtures containing an organic molecule and graphene oxide or graphite oxide in an amount sufficient to catalyze a reaction of the organic molecule.
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Page/Page column 43-46
(2011/12/14)
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- C-H oxidation using graphite oxide
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Graphite oxide was found to be an effective oxidant for use in a broad range of reactions, including the oxidation of olefins to their respective diones, methyl benzenes to their respective aldehydes, diarylmethanes to their respective ketones, and various dehydrogenations. The temperatures used in the reactions were typically mild (100-120 °C), and the heterogeneous nature of the oxidant facilitated isolation and purification of the desired products. In most cases, no by-products were observed and the desired products were isolated in good to excellent yields.
- Jia, Hong-Peng,Dreyer, Daniel R.,Bielawski, Christopher W.
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experimental part
p. 4431 - 4434
(2011/08/06)
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- Tuning the redox chemistry of 4-benzoyl-N-methylpyridinium cations through para substitution. Hammett linear free energy relationships and the relative aptitude of the two-electron reduced forms for H-bonding
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In anhydrous CH3CN a series of nine 4-(4-substituted-benzoyl)-N-methylpyridinium cations (substituent: -OCH3, -CH3, -H, -SCH3, -Br, -C≡CH, -CHO, -NO2, and -+S(CH3)2) demonstrate two chemically reversible, well-separated one-electron (1-e) reductions in the same potential range as other main stream redox catalysts such as quinones and viologens. Hammett linear free energy plots yield excellent correlation between the E1/2 values of both waves and the substituent constants σp-X. The reaction constants for the two 1-e reductions are ρ1 = 2.60 and ρ2 = 3.31. The lower ρ1 value is associated with neutralization of the pyridinium ring, and the higher ρ2 value with the negative charge developing during the 2nd-e reduction. Structure-function correlations point to a purely inductive role for substitution in both 1-e reductions. The case of the 4-(4-nitrobenzoyl)-N-methylpyridinium cation is particularly noteworthy, because the 4-nitrobenzoyl moiety undergoes reduction before the 2nd reduction of the 4-benzoyl-N-methylpyridinium system. Correlation of the third wave of this compound with the 2nd-e reduction of the others yields σp-NO2- = -0.97 ± 0.02, thus placing the -NO2- group among the strongest electron donors. Solvent deuterium isotope effects and maps of the electrostatic potential (via PM3 calculations) as a function of substitution support that 2-e reduced forms develop H-bonding with proton donors (e.g., CH3-OH) via the O-atom. The average number of CH3OH molecules entering the H-bonding association increases with e-donating substituents. H-bonding shifts the 2nd reduction wave closer to the first one. This has important practical implications, because it increases the equilibrium concentration of the 2-e reduced form from disproportionation of the 1-e reduced form.
- Leventis, Nicholas,Rawaswdeh, Abdel-Monem M.,Zhang, Guohui,Elder, Ian A.,Sotiriou-Leventis, Chariklia
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p. 7501 - 7510
(2007/10/03)
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- Hydroxide-promoted redox reactions in water of α-phenyl-4-nitrobenzenemethanol, α-(p-nitrophenyl)-4-pyridinemethanol, and α-(p-Nitrophenyl)-4-pyridinemethanol N-oxide steric inhibition of resonance
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α-Phenyl-4-nitrobenzenemethanol (3) reacted with 1 M sodium hydroxide to yield 4,4′-dibenzoylazoybenzene (5) (51%), 4-hydroxy-4′-benzoylazobenzene (6) and benzoic acid (12% each), and smaller amounts of 4-aminobenzophenone and 4-nitrobenzophenone. Both α-phenyl-2-nitrobenzenemethanol (9) and 3,5-dimethyl-4-nitrobenzenemethanol (10a) did not react with 1 M sodium hydroxide, presumably due to steric hindrance. α-(p-Nitrophenyl)-4-pyridinemethanol (14) and its N-oxide 11 with 1 M sodium hydroxide yielded 4,4′-diaroylazoxybenzenes 15a and 12a, respectively, 4,4′-diaroylazobenzenes 15b and 12b, respectively, as well as 4-hydroxy-4′-aroylazobenzenes 16 and 13, respectively. The relative reaction rates were 11 > 14 > 3. Studies with 11 showed that the nitro group is involved in the redox reaction in preference to the N-oxide group.
- Muth, Chester W.,Yang, Kaipeen E.
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p. 249 - 254
(2007/10/03)
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- Studies on the Insecticidal Activities of Some New N-Benzoyl-N'-Arylureas
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This paper reports the synthesis and the insecticidal activities of some N-benzoyl-N'-arylureas 4-arylsubstituted with alkylated or halogenated aroyl moieties. The compounds, tested against some representative insect species, displayed very high activity against Aedes aegypti, especially the halosubstituted derivatives. None of the newly synthesized compounds showed genotoxic activity in the Bacillus subtilis rec-assay and in the Salmonella-microsome test.
- Carmellino, Maria L.,Pagani, Giuseppe,Pregnolato, Massimo,Terreni, Marco,Caprioli, Vincenzo,Zani, Franca
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p. 227 - 236
(2007/10/03)
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