- Copper(II)-catalyzed electrophilic amination of quinoline N-oxides with O-benzoyl hydroxylamines
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Copper acetate-catalyzed C-H bond functionalization amination of quinoline N-oxides was achieved using O-benzoyl hydroxylamine as an electrophilic amination reagent, thereby affording the desired products in moderate to excellent yields. Electrophilic amination can also be performed in good yield on a gram scale. This journal is
- Li, Gang,Jia, Chunqi,Sun, Kai,Lv, Yunhe,Zhao, Feng,Zhou, Kexiao,Wu, Hankui
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- The Mechanism of Thermal Eliminations. Part 21. Rate Data for Pyrolysis of 2-Ethoxyquinoline, 1-and 3-Ethoxyisoquinoline, and 1-Ethoxythiazole: Correlation of Reactivities with ?-Bond Order of the C=N Bond
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We have measured the rates of thermal elimination of ethylene from the title compounds between 587.3 and 722.9 K.The reactivities relative to 2-ethoxypyridine at 650 K are: 3-ethoxyisoquinoline (0.21), 2-ethoxyquinoline (3.13), 1-ethoxyisoquinoline (6.47), 2-ethoxythiazole (63.1).These reactivities parallel the ?-bond order of the C=N bond, though the exceptional reactivity of 2-ethoxythiazole is attributed to additional acceleration through +M electron release from sulphur to nitrogen.This emphasizes the greater relative importance of nucleophilic attack by the nitrogen upon the β-hydrogen atom as compared with the analogous mechanism for pyrolysis of esters.Because of semi-concentrated nature of the reaction, interruption of aromaticity is much less significant than in, for example, electrophilic aromatic substitution.Thus retention of the benzenoid character of the ring not involved in the elimination is not an important rate-determining feature, as shown by the lower reactivity of 3-ethoxyisoquinoline relative to 2- ethoxypyridine.The unimportance of the interruption of aromaticity of the benzenoid ring means that conjugative effects are better relayed to nitrogen in the β-naphthalene-like position (isoquinoline) than in the α-naphthalene-like position (quinoline).This is the reverse of the familiar pattern for reactions of naphthalene-like systems where full charges are involved, and may be an additional factor contributing to the higher reactivity of 1-ethoxyisoquinoline than of 2-ethoxyquinoline, as may also be the -I effect of the benzo substiutent.The conclusions are used to predict elimination rates for alkoxyheterocycles not yet studied.
- Al-Awadi, Nouria,Taylor, Roger
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- Elimination of Carbon Monoxide by Electron Impact on Quinoline N-oxide, Carbostyril and 8-Hydroxyquinoline
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Under electron impact, the molecular ions of quinoline N-oxide, carbostyril and 8-hydroxyquinoline lose carbon monoxide giving a fragment ion C8H7N (m/z 117), which was shown by collision-activated dissociation in each case to have the structure of the molecular ion of indole.Its formation from 8-hydroxyquinoline requires an unusual rearrangement.Isoquinoline N-oxide loses HCN rather than CO and gives a fragment which has the structure of the molecular ion of benzofuran.When the first three compounds were subjected to flash vacuum pyrolysis, quinoline N-oxide at 500-700 deg C gave carbostyril and indole was detected by gas chromatography/mass spectrometry.At 900 deg C carbostyril and 8-hydroxyquinoline both gave indole in small amounts, detected by gas chromatography/mass spectrometry.
- Blumenthal, Thomas,Gillis, Richard G.,Porter, Quentin N.,Yeoh, Li Li
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- Cu(II)-Catalyzed Construction of Heterobiaryls using 1-Diazonaphthoquinones: A General Strategy for the Synthesis of QUINOX and Related P,N Ligands
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An efficient and straightforward method was developed for the synthesis of heterobiaryls using easily available N-oxides and diazonaphthoquinones under cheap Cu(II) catalysis. The developed method offered QUINOX and related congeners in a simple manner. A wide scope of important heterobiaryls was achieved with high site selectivity. The synthesized naphthols were transformed into the privileged related P,N ligands. Suitable resolution methods can directly afford the corresponding axially chiral heterobiaryls.
- Biswas, Aniruddha,Pan, Subarna,Samanta, Rajarshi
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p. 1631 - 1636
(2022/03/14)
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- Method for preparing sulfone and N-oxygen compound by using green and efficient oxidation system
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The invention discloses a method for preparing sulfone and N-oxygen compound by using a green and efficient oxidation system. The method comprises the following steps of: by using a tertiary amine compound or aromatic thioether or fatty thioether compound as a raw material, H2O2 as an oxidant, methanol as a reaction solvent and potassium carbonate as an alkali, introducing sulfuryl fluoride 5O2F2gas as an accelerator; performing stirring at room temperature under a sealed condition for oxidation reaction; and after finishing the reaction, filtering to remove solid potassium carbonate, dryingto remove water, filtering to obtain a crude product, and finally carrying out column chromatography separation to obtain a pure product. Tertiary amine is oxidized into an N-oxygen compound, and thethioether is oxidized into sulfone. According to the method, the sulfuryl fluoride (SO2F2) which is very cheap and easy to obtain is used as the reaction promoter, green and environment-friendly hydrogen peroxide (H2O2) is used as an oxidizing agent, and so that the yield of the reaction is generally high; after the reaction, byproducts are only water and inorganic salts (SO4 and F) whichare easy to remove and free of pollution, and the green and efficient oxidation system can be realized, and therefore, the method is suitable for large-scale industrial production.
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Paragraph 0030-0032
(2021/01/29)
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- SO2F2-mediated oxidation of primary and tertiary amines with 30% aqueous H2O2 solution
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A highly efficient and selective oxidation of primary and tertiary amines employing SO2F2/H2O2/base system was described. Anilines were converted to the corresponding azoxybenzenes, while primary benzylamines were transformed into nitriles and secondary benzylamines were rearranged to amides. For tertiary amine substrates quinolines, isoquinolines and pyridines, their oxidation products were the corresponding N-oxides. The reaction conditions are very mild and just involve SO2F2, amines, 30% aqueous H2O2 solution, and inorganic base at room temperature. One unique advantage is that this oxidation system is just composed of inexpensive inorganic compounds without the use of any metal and organic compounds.
- Liao, Xudong,Zhou, Yi,Ai, Chengmei,Ye, Cuijiao,Chen, Guanghui,Yan, Zhaohua,Lin, Sen
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supporting information
(2021/11/01)
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- Waste-minimized synthesis of C2 functionalized quinolines exploiting iron-catalysed C-H activation
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Herein we present an efficient and regioselective iron-catalyzed methodology for the external oxidant-free functionalization of quinoline-N-oxides. The protocol, based on the use of inexpensive and easily accessible FeSO4, showed broad applicability to a wide range of substrates. An additional green feature of this synthetic methodology is H2O being the only by-product. Experimental and computational investigations provide support to a mechanism based on a facile C-H activation event. The green efficiency of the process has also been carefully assessed using: (i) metrics related to the synthetic process (AE, Yield, 1/SF, MRP and RME); (ii) safety/hazard metrics (SHZI and SHI); and (iii) metrics related to the metal used as the catalyst (Abundance, OEL and ADP). In addition to the many advantages of this protocol related to the green iron catalyst used and the safety/hazard features of the process, an E-factor value of ca. 0.92 (84 to >99% reduction compared to known protocols) evidently confirms the sustainable efficiency of the procedure presented. Practical utility has also been demonstrated by performing the reaction efficiently on a multi-gram scale. This journal is
- Ferlin, Francesco,Zangarelli, Agnese,Lilli, Simone,Santoro, Stefano,Vaccaro, Luigi
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supporting information
p. 490 - 495
(2021/01/28)
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- Rhodium-Catalyzed Atroposelective Construction of Indoles via C?H Bond Activation
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Reported herein is the rhodium(III)-catalyzed C?H activation of anilines bearing an N-isoquinolyl directing group for oxidative [3+2] annulation with four classes of internal alkynes, leading to atroposelective indole synthesis via dynamic kinetic annulation with C-N reductive elimination constituting the stereo-determining step. This reaction proceeds under mild conditions with high regio- and enantioselectivity and functional group compatibility.
- Sun, Lincong,Chen, Haohua,Liu, Bingxian,Chang, Junbiao,Kong, Lingheng,Wang, Fen,Lan, Yu,Li, Xingwei
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supporting information
p. 8391 - 8395
(2021/03/03)
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- Visible-Light-Induced Decarboxylative Acylation of Pyridine N-Oxides with α-Oxocarboxylic Acids Using Fluorescein Dimethylammonium as a Photocatalyst
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Herein, the development of a visible-light-induced catalytic system to achieve the decarboxylative acylation of pyridine N-oxides with α-oxocarboxylic acids, at room temperature and using the organic dye fluorescein dimethylammonium as a new type of photocatalyst, is reported. A series of 2-arylacylpyridine N-oxides were selectively synthesized in moderate to good yields by controlling the polarity of the reaction solvent. The developed strategy was successfully applied in the synthesis of an important intermediate of the drug, acrivastine, on a gram scale. Notably, this is the first time that fluorescein dimethylammonium has been used to catalyze the Minisci-type C?H decarboxylative acylation reaction. The mechanism of decarboxylative acylation was studied by capturing adducts of acyl radicals and 1,1-diphenylethylene to confirm a radical mechanism. The disclosed catalytic system provides a green synthetic strategy for decarboxylative acylation without the use of additional oxidants or metal catalysts. (Figure presented.).
- Hou, Chuanfu,Sun, Shouneng,Liu, Ziqi,Zhang, Hui,Liu, Yue,An, Qi,Zhao, Jian,Ma, Junjie,Sun, Zhizhong,Chu, Wenyi
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supporting information
p. 2806 - 2812
(2021/04/15)
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- Design, synthesis, and biological evaluation of isoquinolin-1(2H)-one derivates as tankyrase-1/2 inhibitors
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To investigate structure-activity relationships of tankyrase (TNKS) inhibitors, twelve new derivatives of isoquinolin- 1(2H)-one were designed and synthesized, and biological assessments were conducted. Several potent TNKS inhibitors with single- or double-digit nanomolar IC50 values were identified using enzymatic assays. Compound 11c was the most potent compound of this series and inhibited TNKS1 and TNKS2 at an IC50 of 0.009 and 0.003 μM, respectively, and showed an IC50 of 0.029 μM in a DLD-1 SuperTopFlash assay. Molecular docking results showed that compound 11c occupied a unique subpocket and formed a hydrogen bond with Glu1138 of TNKS2, which was not consistent with the patterns of known TNKS inhibitors and thus warrants further research.
- MO, JIANGWEN,PENG, YAN,WANG, YANYAN,WANG, ZHU,YAO, HAIPING
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p. 132 - 137
(2021/05/31)
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- From Pyridine- N-oxides to 2-Functionalized Pyridines through Pyridyl Phosphonium Salts: An Umpolung Strategy
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The reactions of pyridine-N-oxides with Ph3P under the developed conditions provide an unprecedented route to (pyridine-2-yl)phosphonium salts. Upon activation with DABCO, these salts readily serve as functionalized 2-pyridyl nucleophile equivalents. This umpolung strategy allows for the selective C2 functionalization of the pyridine ring with electrophiles, avoiding the generation and use of unstable organometallic reagents. The protocol operates at ambient temperature and tolerates sensitive functional groups, enabling the synthesis of otherwise challenging compounds.
- Bugaenko, Dmitry I.,Yurovskaya, Marina A.,Karchava, Alexander V.
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supporting information
p. 6099 - 6104
(2021/08/03)
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- Efficient visible light mediated synthesis of quinolin-2(1H)-ones from quinolineN-oxides
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Quinolin-2(1H)-ones are one of the important classes of compounds due to their prevalence in natural products and in pharmacologically useful compounds. Here we present an unconventional and hitherto unknown photocatalytic approach to their synthesis from easily available quinoline-N-oxides. This reagent free highly atom economical photocatalytic method, with low catalyst loading, high yield and no undesirable by-product, provides an efficient greener alternative to all conventional synthesis reported to date. The robustness of the methodology has been successfully demonstrated with easy scaling up to the gram scale.
- Bhuyan, Samuzal,Chhetri, Karan,Hossain, Jagir,Jana, Saibal,Mandal, Susanta,Roy, Biswajit Gopal
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supporting information
p. 5049 - 5055
(2021/07/29)
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- Copper/manganese oxide catalyzed regioselective amination of quinoline N-oxides: An example of synergistic cooperative catalysis
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An atom economical and efficient protocol for C-2 amination of quinoline N-oxides using our synthesized recyclable heterogeneous Cu–MnO catalyst has been reported here. Direct C[sbnd]H aminations of heterocyclic N-oxides with secondary amine were carried out under base, and ligand-free conditions in good to excellent yields. The major advantage is that air is used as a sole oxidant and our catalyst is recycled several times.
- Ghosh, Subhash Chandra,Panda, Asit Baran,Sahoo, Tapan,Thakur, Dinesh
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supporting information
(2021/09/29)
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- Visible-Light-Induced ortho-Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes
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The photocatalyzed ortho-selective migration on a pyridyl ring has been achieved for the site-selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by the selective addition of a CF3 radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically valuable C2-fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P-centered radicals. The utility of this transformation was further demonstrated by the late-stage functionalization of complex bioactive molecules.
- Jeon, Jinwon,He, Yu-Tao,Shin, Sanghoon,Hong, Sungwoo
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supporting information
p. 281 - 285
(2019/11/26)
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- Deoxygenative Amination of Azine-N-oxides with Acyl Azides via [3 + 2] Cycloaddition
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A transition-metal-free deoxygenative C-H amination reaction of azine-N-oxides with acyl azides is described. The initial formation of an isocyanate from the starting acyl azide via a Curtius rearrangement can trigger a [3 + 2] dipolar cycloaddition of polar N-oxide fragments to generate the aminated azine derivative. The applicability of this method is highlighted by the late-stage and sequential amination reactions of complex bioactive compounds, including quinidine and fasudil. Moreover, the direct transformation of aminated azines into various bioactive N-heterocycles illustrates the significance of this newly developed protocol.
- Ghosh, Prithwish,Han, Sang Hoon,Han, Sangil,Kim, Dongeun,Kim, In Su,Kim, Saegun,Kwon, Na Yeon,Mishra, Neeraj Kumar
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p. 2476 - 2485
(2020/03/13)
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- Method for preparing azaheterocycle-N-oxides
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The invention relates to a method for preparing azaheterocycle-N-oxides. The method is concretely characterized in that pyridine, quinoline and isoquinoline compounds, which are used as raw materials,are oxidized under the action of a catalyst to obtain the corresponding N-oxides. The method for preparing azaheterocycle-N-oxides is a preparation method having the advantages of high yield, low cost, easiness in operation, and suitableness for industrialization.
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Paragraph 0032-0033
(2019/09/14)
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- A Biocatalytic Synthesis of Heteroaromatic N-Oxides by Whole Cells of Escherichia coli Expressing the Multicomponent, Soluble Di-Iron Monooxygenase (SDIMO) PmlABCDEF
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Aromatic N-oxides (ArN?OX) are desirable biologically active compounds with a potential for application in pharmacy and agriculture industries. As biocatalysis is making a great impact in organic synthesis, there is still a lack of efficient and convenient enzyme-based techniques for the production of aromatic N-oxides. In this study, a recombinant soluble di-iron monooxygenase (SDIMO) PmlABCDEF overexpressed in Escherichia coli was showed to produce various aromatic N-oxides. Out of 98 tested N-heterocycles, seventy were converted to the corresponding N-oxides without any side oxidation products. This whole-cell biocatalyst showed a high activity towards pyridines, pyrazines, and pyrimidines. It was also capable of oxidizing bulky N-heterocycles with two or even three aromatic rings. Being entirely biocatalytic, our approach provides an environmentally friendly and mild method for the production of aromatic N-oxides avoiding the use of strong oxidants, organometallic catalysts, undesirable solvents, or other environment unfriendly reagents. (Figure presented.).
- Petkevi?ius, Vytautas,Vaitekūnas, Justas,Taurait?, Daiva,Stankevi?iūt?, Jonita,?arlauskas, Jonas,??nas, Narimantas,Me?kys, Rolandas
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supporting information
p. 2456 - 2465
(2019/01/25)
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- Strategic Approach on N-Oxides in Gold Catalysis – A Case Study
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An extensive kinetic study of selected key reactions of (oxidative) gold catalysis concentrates on the decrease of the catalytic activity due to inhibition of the gold(I) catalyst caused by pyridine derivatives that are obtained as by-products if N-oxides are applied as oxygen donors. The choice of the examined pyridine derivatives and their corresponding N-oxides has been made regardless of their commercial availability; particular attention has been paid to the practical benefit which up to now has been neglected in most of the reaction screenings. The test reactions were monitored by GC and 1H NMR spectroscopy. The received reaction constants provide information concerning a correlation between the electronic structure of the heterocycle and the catalytic activity. Based on the collected kinetic data, it was possible to develop a basic set of three N-oxides which have to be taken into account in further oxidative gold(I)-catalyzed reactions. (Figure presented.).
- Schie?l, Jasmin,Stein, Philipp M.,Stirn, Judith,Emler, Kirsten,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 725 - 738
(2018/10/20)
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- Hypervalent Iodine(III)-Mediated Regioselective Cyanation of Quinoline N-Oxides with Trimethylsilyl Cyanide
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A regioselective cyanation of quinoline N-oxides with trimethylsilyl cyanide was developed by using (Diacetoxyiodo) benzene (PIDA) as mediated hypervalent iodine(III) reagent under metal-free and base-free reaction conditions to obtain 2-cyanoquinolines. The efficient PIDA reagent could play the role of an activator of the substrates and an accelerator of N?O bond cleavage. The reaction system featured a wide range of substrate suitability and high yields. The procedure was enlarged gram-scale to synthesize the tuberculosis (TB) inhibitor. Finally, according to some experimental results, a plausible mechanism for the cyanation reaction is proposed. (Figure presented.).
- Xu, Feng,Li, Yuqin,Huang, Xin,Fang, Xinjie,Li, Zhuofei,Jiang, Hongshuo,Qiao, Jingyi,Chu, Wenyi,Sun, Zhizhong
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supporting information
p. 520 - 525
(2018/12/13)
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- Catalyst-Free Synthesis of 2-Anilinoquinolines and 3-Hydroxyquinolines via Three-Component Reaction of Quinoline N-Oxides, Aryldiazonium Salts, and Acetonitrile
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A rapid microwave-assisted, catalyst-free, three-component synthesis of various 2-anilinoquinolines from quinoline N-oxides and aryldiazonium salts in acetonitrile under microwave irradiation is reported. This reaction utilizes acetonitrile as a single nitrogen source and involves the formation of two new C-N bonds via the formal [3 + 2] cycloaddition reaction. In the case of 2-substituted quinolines, 3-hydroxyquinoline was observed as the main product via a 1,3 shift of the oxygen atom from N-oxide to the C3 position of quinolines.
- Dhiman, Ankit Kumar,Chandra, Devesh,Kumar, Rakesh,Sharma, Upendra
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p. 6962 - 6969
(2019/06/14)
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- Synergy of anodic oxidation and cathodic reduction leads to electrochemical deoxygenative C2 arylation of quinoline: N-oxides
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The first example of electrochemical deoxygenative C2 arylation of quinoline N-oxides using sulfonyl hydrazines was demonstrated in this work. By employing both anodic oxidation and cathodic reduction, a variety of 2-arylquinolines were synthesized under metal catalyst-, exogenous-oxidant-, and exogenous-reductant-free conditions.
- Yuan, Yong,Jiang, Minbao,Wang, Tao,Xiong, Yunkui,Li, Jun,Guo, Huijiao,Lei, Aiwen
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supporting information
p. 11091 - 11094
(2019/09/20)
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- Regioselective Cyanation of Six-Membered N-Heteroaromatic Compounds Under Metal-, Activator-, Base- and Solvent-Free Conditions
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A regioselective cyanation of heteroaromatic N-oxides with trimethylsilyl cyanide has been developed to obtain 2-substituted N-heteroaromatic nitrile without the requirement of any external activator-, metal-, base-, and solvent. The present protocol is a straightforward, one-pot heteroaromatic C?H cyanation process, and proceeds smoothly in conventional heating but also under microwave irradiation with shorter reaction times. This approach now allows access to a broad class of quinoline N-oxides and other heteroarene N-oxides with high to good yields and can also be scaled up to obtain gram quantities. Further application of this process was observed and utilized in late-stage cyanation of the anti-malarial drug quinine as well as transformation of the 2-cyanoazines to a series of biologically important molecules. Based on the experimental observations, a plausible mechanism has also been proposed highlighting the dual role of trimethylsilyl cyanide as a nitrile source and as an activating agent. (Figure presented.).
- Sarmah, Bikash Kumar,Konwar, Monuranjan,Bhattacharyya, Dipanjan,Adhikari, Priyanka,Das, Animesh
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supporting information
p. 5616 - 5625
(2019/11/22)
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- Electrochemical Deoxygenation of N-Heteroaromatic N -Oxides
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An electrochemical method for the deoxygenation of N-heteroaromatic N -oxide to give the corresponding N-heteroaromatics has been developed. Several classes of N-heterocycles such as pyridine, quinoline, isoquinoline, and phenanthridine are tolerated. The electrochemical reactions proceed efficiently in aqueous solution without the need for transition-metal catalysts and waste-generating reducing reagents.
- Xu, H.-C.,Xu, P.
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supporting information
p. 1219 - 1221
(2019/06/08)
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- Pd-Catalyzed Direct C-H Alkenylation and Allylation of Azine N -Oxides
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A Pd-catalyzed direct C2-alkenylation of azine N-oxides with allyl acetate is disclosed. The products are formed through an allylation/isomerization cascade process. The use of a tri-tert-butylphosphonium salt as the ligand precursor and KF is mandatory for optimal yields. When cinnamyl acetate is used, the same catalytic system promotes C2-cinnamylation of the azine N-oxide without subsequent isomerization. A mechanism is proposed on the basis of experimental studies and DFT calculations.
- Roudesly, Fares,Veiros, Luis F.,Oble, Julie,Poli, Giovanni
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supporting information
p. 2346 - 2350
(2018/04/30)
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- Method for synthesizing quinoline oxynitride from quinoline compound by ultrasonic-assisted oxidation
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The invention discloses a method for synthesizing quinoline oxynitride from a quinoline compound by ultrasonic-assisted oxidation. The quinoline compound and hydrogen peroxide are subjected to nitrogen oxidation reaction under the ultrasonic-assisted condition and perfluorosulfonic acid resin (Nafion-H) catalytic action to obtain quinoline oxynitride. The method has the advantages that the raw materials are easy to obtain, reaction conditions are simple and mild, greenness and energy conservation are achieved, and reaction selectivity and yield are high; energy is saved and the compatibility of substrate functional groups is excellent; in particular, the perfluorosulfonic acid resin can be recycled as an acid catalyst, so that not only is the reaction cost reduce, but also the reaction yield is increased, also the pollution problem in traditional oxidation reaction is avoided and a relatively high application value is achieved.
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Paragraph 0085; 0086; 0087
(2018/06/21)
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- Transition-Metal-Free Regioselective Alkylation of Quinoline N-Oxides via Oxidative Alkyl Migration and C?C Bond Cleavage of tert-/sec-Alcohols
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An unprecedented C2-alkylation of quinoline N-oxide derivatives via C?C bond activation of tert- and sec-alkyl alcohol is described using hypervalent iodine (III) reagent PhI(OAc)2 (PIDA). This regioselective alkylation using mild hypervalent iodine reagents is more practical, operationally simple and transition metal free. The reaction proceeds efficiently with a broad range of substrates including quinoline, isoquinoline, and pyridine N-oxides using a variety of tert-/sec- alcohols. From experimental outcome, we also propose a rationalized mechanism, mediated by PIDA. (Figure presented.).
- Sen, Chiranjit,Ghosh, Subhash C.
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supporting information
p. 905 - 910
(2018/01/11)
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- Dehydrogenative etherification homocoupling of heterocyclic N-oxides
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A novel approach was developed for the dehydrogenative etherification homocoupling of heterocyclic N-oxides in the presence of silver oxide and PyBroP. Various substrates were well tolerated and the desired products were obtained in moderate to good yields. Generally, this reaction features excellent functional group compatibility, broad substrate scope and good regioselectivity.
- Zhang, Dong,Qiao, Kai,Yuan, Xin,Zheng, Mingwei,Fang, Zheng,Wan, Li,Guo, Kai
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supporting information
p. 1752 - 1756
(2018/04/10)
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- Pyridine synthesis of heterocyclic nitrogen oxide
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The invention provides a synthesis method of pyridine heterocycle oxynitrides, which comprises the following steps: mixing a catalyst {Mo132}, pyridine compounds and 30% hydrogen peroxide in a mole ratio of 1:143:714 in a mixed solvent composed of ethanol and water in a volume ratio of 2:3 at room temperature to react for 6-24 hours, extracting with a dichloromethane organic solvent, and purifying by distilling with an organic phase dichloromethane to obtain the pyridine heterocycle oxynitride product. Compared with the past systems, the catalytic system can complete the catalytic oxidation of the pyridine compounds and quinoline compounds at room temperature within a short time, is reusable and has high yield.
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Paragraph 0024; 0025
(2017/08/25)
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- C3-CARBON LINKED GLUTARIMIDE DEGRONIMERS FOR TARGET PROTEIN DEGRADATION
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This invention provides Degronimers that have carbon-linked E3 Ubiquitin Ligase targeting moieties (Degrons), which can be linked to a targeting ligand for a protein that has been selected for in vivo degradation, and methods of use and compositions thereof as well as methods for their preparation.
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Page/Page column 342; 343
(2017/12/05)
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- A pyridine nitrogen oxide high-efficient, multi-phase catalytic preparation method
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The invention discloses a high efficient heterogeneous catalytic preparation method of pyridine oxynitride. In the provided preparation method, mono-substituted or poly-substituted pyridines or pyridine derivatives are taken as the primary raw materials, titanium dioxide loaded on tungsten (WO3/TiO2) is taken as the catalyst, hydrogen peroxide is taken as the oxidizing agent, and reactions are carried out in a water solution at a room temperature so as to obtain the target product. Compared with the prior art, the preparation method has the following advantages: (1) the provided oxidation method, no acetic acid is used, and thus the requirements on equipment are greatly reduced; (2) a heterogeneous catalytic method is adopted to prepare pyridine oxynitride, the catalyst can be separated from the reaction system through simple filtration or centrifugation, and the operation is convenient; (3) titanium dioxide loaded on tungsten is taken as the catalyst, pyridine oxynitride is prepared by one step in a water solution at a room temperature, the reaction conditions are mild, and the pollution to the environment is little.
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Paragraph 0139; 0143; 0144; 0145
(2017/08/25)
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- Iodine/TBHP-Promoted One-Pot Deoxygenation and Direct 2-Sulfonylation of Quinoline N-Oxides with Sodium Sulfinates: Facile and Regioselective Synthesis of 2-Sulfonylquinolines
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A highly efficient iodine/TBHP-mediated one-pot deoxygenative and regioselective 2-sulfonylation of quinoline N-oxides with sodium sulfinate salts has been developed. This metal-, base-, and phosphorus-free protocol employs readily accessible and easy-to-handle reagents and can be conveniently carried out at room temperature under mild conditions, providing an alternative access to a series of 2-sulfonylquinolines and other related heteroaryl sulfone products in moderate-to-excellent yields within a short reaction time.
- Sumunnee, Ladawan,Buathongjan, Chonchanok,Pimpasri, Chaleena,Yotphan, Sirilata
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supporting information
p. 1025 - 1032
(2017/02/15)
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- Metal-free phosphonation of heteroarene N-oxides with trialkyl phosphite at room temperature
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A new protocol is described for the conversion of heteroarene N-oxides to heteroarylphosphonates through in situ activation with bromotrichloromethane. The N-oxides of isoquinoline, quinoline, quinoxaline and 1,10-phenanthroline were fast transformed into the corresponding heteroarylphosphonates in up to 92% yield under mild conditions in the absence of solvent and metal catalysts. The good functional group tolerance, low cost, feasibility of scale up, and wide availability of reagents make this method a prominent complement to the Hirao coupling.
- Chen, Ming-Tao,You, Xia,Bai, Li-Gang,Luo, Qun-Li
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supporting information
p. 3165 - 3169
(2017/04/21)
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- Copper-Catalyzed Direct, Regioselective Arylamination of N-Oxides: Studies to Access Conjugated π-Systems
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An efficient copper(I)-catalyzed direct regioselective arylamination of various heterocyclic N-oxides was achieved successfully under redox-neutral conditions using anthranils as arylaminating reagents. The developed protocol is simple, straightforward, and economic with a broad range substrate scope. The dual functional groups in the final molecules were utilized to construct structurally and functionally diverse nitrogen-containing organic π-conjugated systems.
- Biswas, Aniruddha,Karmakar, Ujjwal,Nandi, Shiny,Samanta, Rajarshi
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p. 8933 - 8942
(2017/09/11)
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- C2-Alkenylation of N-heteroaromatic compounds: Via Br?nsted acid catalysis
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Substituted heteroaromatic compounds, especially those based on pyridine, hold a privileged position within drug discovery and medicinal chemistry. However, functionalisation of the C2 position of 6-membered heteroarenes is challenging because of (a) the difficulties of installing a halogen at this site and (b) the instability of C2 heteroaryl-metal reagents. Here we show that C2-alkenylated heteroaromatics can be accessed by simple Br?nsted acid catalysed union of diverse heteroarene N-oxides with alkenes. The approach is notable because (a) it is operationally simple, (b) the Br?nsted acid catalyst is cheap, non-toxic and sustainable, (c) the N-oxide activator disappears during the reaction, and (d) water is the sole stoichiometric byproduct of the process. The new protocol offers orthogonal functional group tolerance to metal-catalysed methods and can be integrated easily into synthetic sequences to provide polyfunctionalised targets. In broader terms, this study demonstrates how classical organic reactivity can still be used to provide solutions to contemporary synthetic challenges that might otherwise be approached using transition metal catalysis.
- Crisenza, Giacomo E. M.,Dauncey, Elizabeth M.,Bower, John F.
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supporting information
p. 5820 - 5825
(2016/07/06)
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- The microwave-assisted ortho-alkylation of azine N-oxides with N-tosylhydrazones catalyzed by copper(i) iodide
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A copper catalyzed regioselective cross-coupling of N-tosylhydrazones with azine N-oxides to yield ortho-alkylated products in moderate to good yields is reported. The reaction is facilitated by microwave, takes place without any ligand, and uses inexpensive copper(i) iodide as the catalyst.
- Jha, Abadh Kishor,Jain, Nidhi
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supporting information
p. 1831 - 1834
(2016/02/05)
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- Catalyst-free and selective oxidation of pyridine derivatives and tertiary amines to corresponding N-oxides with 1,2-diphenyl-1,1,2,2-tetrahydroperoxyethane
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The catalyst-free oxidation of various pyridine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields. Graphical abstract: The catalyst-free oxidation of various pyridine derivatives and tertiary amines to their corresponding N-oxides with 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as an efficient oxidant has been developed. The methodology proved to tolerate a number of functional groups. The reactions proceeded smoothly under solvent-free and mild conditions at room temperature. All the products were easily extracted from the reaction mixtures in excellent yields.
- Azarifar, Davood,Mahmoudi, Boshra
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p. 645 - 651
(2016/02/19)
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- Regioselective Chlorination of Quinoline N-Oxides and Isoquinoline N-Oxides Using PPh3/Cl3CCN
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A novel method for the regioselective C2-chlorination of heterocyclic N-oxides has been developed. PPh3/Cl3CCN were used as chlorinating reagents and the desired N-heterocyclic chlorides were obtained smoothly in satisfactory yields. The reactions proceeded in a highly efficient and selective manner across a broad range of substrates demonstrating excellent functional group tolerance. In addition, this chlorination reaction can be used for the modification of N-heterocyclic scaffolds of appealing ligands and pharmaceuticals.
- Qiao, Kai,Wan, Li,Sun, Xiaoning,Zhang, Kai,Zhu, Ning,Li, Xin,Guo, Kai
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p. 1606 - 1611
(2016/04/05)
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- A lipase-glucose oxidase system for the efficient oxidation of: N -heteroaromatic compounds and tertiary amines
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In this work, a lipase-glucose oxidase system has been designed and proven to be an efficient system for the oxidation of N-heteroaromatic compounds and tertiary amines. This dual-enzyme system not only displays environmental friendliness, but also demonstrates its huge potential in industrial applications.
- Yang, Fengjuan,Zhang, Xiaowen,Li, Fengxi,Wang, Zhi,Wang, Lei
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supporting information
p. 3518 - 3521
(2016/07/06)
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- Metal-Free, Phosphonium Salt-Mediated Sulfoximination of Azine N-Oxides: Approach for the Synthesis of N-Azine Sulfoximines
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Herein, we report a simple and metal-free method for the synthesis of N-azine sulfoximines by the nucleophilic substitution of azine N-oxides with NH-sulfoximines. The present method works at room temperature with wide functional group compatibility and gives several unprecedented N-azine sulfoximines. The reaction conditions were also found suitable with enantiopure substrates and furnished products without any racemization. It also finds an application in the sulfoximination of azine-based functional molecules such as 2,2′-bipyridine, 1,10-phenanthroline, and quinine.
- Aithagani, Sravan Kumar,Kumar, Mukesh,Yadav, Mahipal,Vishwakarma, Ram A.,Singh, Parvinder Pal
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p. 5886 - 5894
(2016/07/23)
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- Palladium(II)-catalyzed C-C and C-O bond formation for the synthesis of C1-benzoyl isoquinolines from isoquinoline: N -oxides and nitroalkenes
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C1-Benzoyl isoquinolines can be generated via a palladium(ii)-catalyzed C-C and C-O coupling of isoquinoline N-oxides with aromatic nitroalkenes. The reaction proceeds through remote C-H bond activation and subsequent intramolecular oxygen atom transfer (OAT). In this reaction, the N-O bond was designed as a directing group in the C-H bond activation as well as the source of an oxygen atom.
- Li, Jiu-Ling,Li, Wei-Ze,Wang, Ying-Chun,Ren, Qiu,Wang, Heng-Shan,Pan, Ying-Ming
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supporting information
p. 10028 - 10031
(2016/08/15)
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- Cu-Catalyzed Deoxygenative C2-Sulfonylation Reaction of Quinoline N-Oxides with Sodium Sulfinate
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An unexpected Cu-catalyzed deoxygenative C2-sulfonylation reaction of quinoline N-oxides in the presence of radical initiator K2S2O8 was developed that used sodium sulfinate as a sulfonyl coupling partner. The mechanism studies indicate that the reaction proceeds via Minisci-like radical coupling step to give sulfonylated quinoline with good chemical yields.
- Du, Bingnan,Qian, Ping,Wang, Yang,Mei, Haibo,Han, Jianlin,Pan, Yi
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supporting information
p. 4144 - 4147
(2016/08/30)
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- Copper-Catalyzed Regioselective Cascade Alkylation and Cyclocondensation of Quinoline N-Oxides with Diazo Esters: Direct Access to Conjugated π-Systems
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An inexpensive copper-catalyzed cascade regioselective alkylation, followed by cyclocondensation of quinoline N-oxides with α-diazo esters has been achieved successfully to provide heteroarene-containing conjugated π-systems. The developed method is simple, straightforward, and economical with a broad range of substrate scope. The dual role of copper catalyst in the C?H bond functionalization and in Lewis acid-promoted cyclization was explored.
- Biswas, Aniruddha,Karmakar, Ujjwal,Pal, Arun,Samanta, Rajarshi
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supporting information
p. 13826 - 13830
(2016/09/21)
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- Benzylation of heterocyclic N-oxides via direct oxidative cross-dehydrogenative coupling with toluene derivatives
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A novel cross-dehydrogenative coupling (CDC) of heterocyclic N-oxides with toluene derivatives has been discussed, allowing for the facile synthesis of a broad range of structurally diverse C1-benzyl quinoline N-oxides, isoquinoline N-oxides and pyridine N-oxides, including two methylated quinoline N-oxides in particular. This protocol not only extends the application of toluenes in synthetic organic chemistry, but also offers an alternative method to prepare benzylated heterocyclic N-oxides without any metal involved, which is important in medicinal chemistry.
- Wan,Qiao,Sun,Di,Fang,Li,Guo
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supporting information
p. 10227 - 10232
(2016/12/07)
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- Facile Immobilization of a Lewis Acid Polyoxometalate onto Layered Double Hydroxides for Highly Efficient N-Oxidation of Pyridine-Based Derivatives and Denitrogenation
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N-Oxides are a class of highly important compounds that are used widely as synthetic intermediates. In this paper, we demonstrate for the first time the use of a polyoxometalate-based composite material as a highly efficient heterogeneous catalyst for the N-oxidation of pyridines and its derivatives in the presence of H2O2 at room temperature. The composite was prepared by the intercalation of the [La(PW11O39)2]11- anion into a layered double hydroxide (LDH) modified with tris(hydroxymethyl)aminomethane (Tris). Additionally, the Tris-LDH-La(PW11)2-based catalyst has been employed for the denitrogenation of a model oil mixture in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate and H2O2. Denitrogenation can be achieved in 40 min at 75 C. Finally, the heterogeneous catalyst can be recovered easily and reused at least 10 times without a measurable decrease of the catalytic activity and disintegration of the Tris-LDH-La(PW11)2 structure. Between the sheets: We demonstrate for the first time the use of a polyoxometalate-based composite material as a highly efficient heterogeneous catalyst for the N-oxidation of pyridines and its derivatives in the presence of H2O2 at room temperature. The composite is prepared by the intercalation of the [La(PW11O39)2]11- anion into a layered double hydroxide modified with tris(hydroxymethyl)aminomethane.
- Liu, Kai,Yao, Zhixiao,Miras, Haralampos N.,Song, Yu-Fei
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p. 3903 - 3910
(2016/01/26)
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- Catalytic system for pyridine oxidation to N-oxides under mild conditions based on polyoxomolybdate
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A reusable and effective catalytic system has been developed for oxidation of pyridines catalyzed by Keplerate polyoxomolybdate ({Mo132}) at room temperature. Pyridine compounds could be oxidized in high yields under mild conditions.
- Yang, Chunxia,Zhao, Wei,Cheng, Zhiguo,Luo, Baomin,Bi, Dongqin
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p. 36809 - 36812
(2015/05/05)
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- External-Photocatalyst-Free Visible-Light-Mediated Synthesis of Indolizines
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A visible-light-mediated synthesis of valuable polycyclic indolizine heterocycles from easily accessed brominated pyridine and enol carbamate derivatives has been developed. This process, which operates at room temperature under irradiation from readily available light sources, does not require the addition of an external photocatalyst. Instead, an investigation into the reaction mechanism indicates that the indolizine products themselves may be in some way involved in mediating and accelerating their own formation. Preliminary studies also show that these simple heterocyclic compounds may be capable of facilitating other visible-light-mediated transformations.
- Sahoo, Basudev,Hopkinson, Matthew N.,Glorius, Frank
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supporting information
p. 15545 - 15549
(2016/01/26)
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- Metal-free methylation of a pyridine N-oxide C-H bond by using peroxides
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Metal-free methylation of a pyridine N-oxide C-H bond was developed using peroxide as a methyl reagent under neat conditions. Pyridine N-oxide derivatives with various groups (e.g., Cl, NO2, and OCH3) were all suitable substrates, and the desired products were obtained in moderate to excellent yields under standard conditions. Moreover, the methylation can be performed with a good yield on the gram-scale experiment. Tentative mechanistic studies show that the methylation is a classical radical process.
- Li, Gang,Yang, Suling,Lv, Bingjie,Han, Qingqing,Ma, Xingxing,Sun, Kai,Wang, Zhiyong,Zhao, Feng,Lv, Yunhe,Wu, Hankui
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supporting information
p. 11184 - 11188
(2015/11/27)
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- A general synthesis of bis(o-azaheteroaryl)methane derivatives from N-oxides of azines and azoles
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A general method of preparation of derivatives of bis(o-azaheteroaryl)methanes from aromatic N-oxides is reported, the key step of which is a 1,3-dipolar cycloaddition between N-oxides of azines or azoles and in situ generated terminal difluoroalkenes containing an o-azaheteroaryl substituent at the double bond. Selected products were applied for the preparation of two novel unsymmetrical analogues of BODIPY fluorescent dyes, containing both an imidazole and a quinoline or isoquinoline unit.
- Szpunar, Magdalena,Loska, Rafa?
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supporting information
p. 2133 - 2137
(2015/03/31)
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- 2,2,2-Trifluoroacetophenone as an organocatalyst for the oxidation of tertiary amines and azines to N-oxides
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A cheap, mild and environmentally friendly oxidation of tertiary amines and azines to the corresponding Noxides is reported by using polyfluoroalkyl ketones as efficient organocatalysts. 2,2,2-Trifluoroacetophenone was identified as the optimum catalyst for the oxidation of aliphatic tertiary amines and azines. This oxidation is chemoselective and proceeds in high-to-quantitative yields utilizing 10 mol% of the catalyst and H2O2 as the oxidant.
- Limnios, Dimitris,Kokotos, Christoforos G.
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supporting information
p. 559 - 563
(2014/04/03)
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- Green and reusable synthetic procedure for pyridine N-oxides catalyzed by a lacunary polyoxometalate
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A lacunary Keggin polyoxometalate of K8[BW11O39H] · 13H2O was used as an effective and reusable catalyst for pyridine oxidation. Good yields of pyridine N-oxides were obtained in this catalytic system with hydrogen peroxide in water under mild conditions. Taylor and Francis Group, LLC.
- Zhao, Wei,Wang, Xing,Yang, Chunxia
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p. 150 - 160
(2013/11/06)
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- Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles
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A Mo/P catalytic system for an efficient gram-scale oxidation of a variety of nitrogen heterocycles to N-oxides with hydrogen peroxide as terminal oxidant has been investigated. Combined spectroscopic and crystallographic studies point to the tetranuclear Mo4P peroxo complex as one of the active catalytic species present in the solution. Based on this finding an optimized catalytic system has been developed. The utility and chemoselectivity of the catalytic system has been demonstrated by the synthesis of over 20 heterocyclic N-oxides.
- Larionov, Oleg V.,Stephens, David,Mfuh, Adelphe M.,Arman, Hadi D.,Naumova, Anastasia S.,Chavez, Gabriel,Skenderi, Behije
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p. 3026 - 3036
(2014/05/06)
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- Trichloroacetonitrile-hydrogen peroxide: A simple and efficient system for the selective oxidation of tertiary and secondary amines
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A variety of tertiary and secondary amines were efficiently oxidized to their corresponding N-oxides and nitrones, respectively, using the trichloroacetonitrile-hydrogen peroxide system. The in situ generated trichloromethylperoxyimidic acid is the active reagent for the oxidation processes.
- Nikbakht, Fatemeh,Heydari, Akbar
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p. 2513 - 2516
(2014/05/06)
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