- Conformational and structural analysis of bis(4-chloroquinoline-N-oxide)hydrogen tribromide
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The X-ray diffraction and conformational study of bis(4-chloroquinoline-N-oxide)hydrogen tribromide is performed. Two conformations corresponding to the minima on the energy curve are found by DFT using the ABINIT software. The model of one of the conformers generally matches with the structure determined experimentally for this compound using X-ray diffraction. In both instances, the structure with the dihedral angle (quinoline - N-O-H) close to 90° is most favorable, which is explained in terms of resonance theory and steric factors. It is concluded that oxygen atoms in the complex are in the sp3 hybridization state and the sp2 hybrid state of the oxygen atom is not possible here due to steric factors.
- Romanov,Nizhnik, Ya. P.,Fofanov
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- Copper-catalyzed intermolecular dehydrogenative amidation/amination of quinoline N-oxides with lactams/cyclamines
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C-H, N-H dehydrogenative coupling of quinoline N-oxides with lactams/cyclamines has been achieved in the presence of the Cu(OAc)2 catalyst to give good to excellent yields. This study provides a new strategy for the construction of a 2-aminoqui
- Li, Gang,Jia, Chunqi,Sun, Kai
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- 13C NMR studies on the structure of 5H- and 6H-indolo-[2,3-b] quinolines and the related compounds
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A set of 13C NMR data which included one-bond spin-spin coupling constants has been obtained for a large series of heteroaromatic compounds. It contains, among others, 6-substituted quinolines, their N-oxides, 2- and 5-methoxyindoles. The results obtained for these basic molecules were compared with those measured for a series of variously substituted 5H- and 6H-indolo[2,3-b]quinolines, which shed new light on the electronic structure of the two latter groups of the compounds.
- Kamieńska-Trela,Kania,Bechcicka,Kaczmarek
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Read Online
- A fluorescence chemosensor based on imidazo[1,2-a]quinoline for Al3+ and Zn2+ in respective solutions
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A new chemosensor, N′-[(2-hydroxyphenyl)methylidene]imidazo[1,2-a]quinoline-2-carbohydrazide (L2), was developed, which could detect Al3+ in DMSO/H2O HEPES buffer and Zn2+ in EtOH/H2O HEPES buffer. The chemosensor exhibits high selectivity and sensitivity for sensing Al3+ and Zn2+ with a fluorescence "turn-on" mode.
- Sun, Junhua,Liu, Zheng,Wang, Ying,Xiao, Shihua,Pei, Meishan,Zhao, Xiuxian,Zhang, Guangyou
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p. 100873 - 100878
(2015)
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- Heterogeneous mesoporous manganese oxide catalyst for aerobic and additive-free oxidative aromatization of N-heterocycles
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Herein, we report a heterogeneous, aerobic, additive-free and environmentally benign catalytic protocol for oxidative aromatization of saturated nitrogen-heterocycles using a mesoporous manganese oxide material. The aromatized products can be separated by easy filtration and the catalyst is reusable for at least four cycles. Mechanistic investigation provides evidence for radical intermediates, a multi-electron redox cycle between Mn centers, and an oxygen exchange mechanism.
- Mullick, Kankana,Biswas, Sourav,Angeles-Boza, Alfredo M.,Suib, Steven L.
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- Graphene oxide as an active carbocatalyst for cyanation of quinoline and isoquinoline N-Oxides
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Graphene oxide was found to be a highly efficient and cost-effective heterogeneous catalyst for the direct metal-free transformation of quinoline and isoquinoline N-oxides into the corresponding nitriles under mild conditions. This method is simple, econo
- Huang, Panpan,Peng, Xiangjun,Qiu, Genhong,Yu, Keyang,Li, Hong,Kong, Lingting,Hu, Jiaming,Chen, Zhengwang,Huang, Qing,Liu, Liangxian
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- Copper-Catalyzed Deoxygenative C2-Sulfonylation of Quinoline N -Oxides with DABSO and Phenyldiazonium Tetrafluoroborates for the Synthesis of 2-Sulfonylquinolines via a Radical Reaction
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An efficient and practical method for the synthesis of 2-sulfonylquinolines through copper-catalyzed deoxygenative C2-sulfonylation of quinoline N -oxides with 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) and phenyldiazonium tetrafluoroborates is demonstrated. Products with various substituents were obtained in moderate to high yields.
- Deng, Qi,Dong, Dao-Qing,Li, Guang-Hui,Wang, Zu-Li,Yan, Shi-Qiang
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- Reductive Amination Revisited: Reduction of Aldimines with Trichlorosilane Catalyzed by Dimethylformamide─Functional Group Tolerance, Scope, and Limitations
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Aldimines, generated in situ from aliphatic, aromatic, and heteroaromatic aldehydes and aliphatic, aromatic, and heteroaromatic primary or secondary amines, can be reduced with trichlorosilane in the presence of dimethylformamide (DMF) as an organocatalys
- Campbell, Joanna L. P.,Davies, Christopher D.,Ho?ek, Jan,Ko?ovsky, Pavel,Kysilka, Ond?ej,Popov, Kirill K.,Pour, Milan
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p. 920 - 943
(2022/01/27)
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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 0021-0023
(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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- Metal-free C8-H functionalization of quinolineN-oxides with ynamides
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The metal-free C8-H functionalization of quinolineN-oxides with ynamides is unveiled for the first time by the intramolecular Friedel-Crafts-type reaction of quinolyl enolonium intermediates generated from Br?nsted acid-catalyzed addition of quinolineN-ox
- Hu, Weican,Zhang, Feiyang,Chen, Chen,Qi, Tianhang,Shen, Yanlong,Qian, Guoying,Rong, Zhouting
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supporting information
p. 6995 - 6998
(2021/07/21)
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- A photochemical C=C cleavage process: Toward access to backbone N-formyl peptides
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Photo-responsive modifications and photo-uncaging concepts are useful for spatiotemporal control of peptides structure and function. While side chain photo-responsive modifications are relatively common, access to photo-responsive modifications of backbone N-H bonds is quite limited. This letter describes a new photocleavage pathway, affording N-formyl amides from vinylogous nitroaryl precursors under physiologically relevant conditions via a formal oxidative C=C cleavage. The N-formyl amide products have unique properties and reactivity, but are difficult or impossible to access by traditional synthetic approaches.
- Ball, Zachary T.,Wang, Haopei
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supporting information
p. 2932 - 2938
(2022/01/12)
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- Deconstructive di-functionalization of unstrained, benzo cyclic amines by C-N bond cleavage using a recyclable tungsten catalyst
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With H2WO4 as the catalyst and H2O2 as the oxidant, we herein report a deconstructive difunctionalization of the C-N bond in unstrained, benzo cyclic amines to generate an ester group and nitro group simultaneously. The preliminary mechanistic studies suggested that the corresponding hydroxamic acid is the key intermediate for this transformation. Importantly, with the utilization of this transformation, we achieved an interesting approach for the ring contraction of quinoline to indole, an example of scaffold hopping in a hetero-aromatic system.
- Zhang, Yujing,Sun, Shuai,Su, Yijin,Zhao, Jian,Li, Yong-Hong,Han, Bo,Shi, Feng
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supporting information
p. 4970 - 4974
(2019/05/29)
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- Synthesis method of N oxide
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The invention relates to the field of organic synthesis, and provides a synthesis method of N oxide aiming at the problem of low yield, which comprises the following steps of: (1) adding an N-containing heterocyclic compound into glacial acetic acid, and dissolving to obtain a premix; (2) adding hydrogen peroxide with the mass concentration of 10%-15% into the premix, wherein the molar ratio of the hydrogen dioxide in the hydrogen peroxide to the N-containing heterocyclic compound is 1-3:1, and the control temperature is 20-110 DEG C, and reacting to obtain a first intermediate; (3) evaporating residual glacial acetic acid in the first intermediate to obtain the N oxide. The glacial acetic acid is oxidized into peroxyacetic acid by adding hydrogen peroxide with the mass concentration of 10-15%, and the N-containing heterocyclic compound is oxidized into a N-oxygen compound by the peroxyacetic acid, so that the yield of more than 98% can be still achieved without adding a catalyst in the reaction, the removal operation of the catalyst is not needed after the reaction is finished, and the experimental operation of the reaction is simpler and more convenient.
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Paragraph 0035-0134
(2019/06/07)
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- The M?CPbA?NH3(G) system: A safe and scalable alternative for the manufacture of (substituted) pyridine and quinoline N?oxides?
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An improved, safe, and scalable isolation process for (substituted) pyridine and quinoline N-oxides in quantitative yields along with high purities using the m-CPBA?NH3(g) system is described. The safety was assessed by reaction calorimetry and differential scanning calorimetry studies for possible hazards during the conversion and isolation steps. Careful interpretation of the data substantiated the safety and scalability. The process flow is simplified to meet the industrial requirements of safety, cost-effectiveness, and utility minimization. The reaction was safely demonstrated at a 2.5 kg scale.
- Palav, Amey,Misal, Balu,Ernolla, Anilkumar,Parab, Vinod,Waske, Prashant,Khandekar, Dileep,Chaudhary, Vinay,Chaturbhuj, Ganesh
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supporting information
p. 244 - 251
(2019/03/17)
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- Cu-Catalyzed carbamoylation: Versus amination of quinoline N -oxide with formamides
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An efficient, direct carbamoylation and amination of quinoline N-oxides with formamides to access 2-carbamoyl and 2-amino quinolines has been developed through copper-catalyzed C-C and C-N bond formations via cross-dehydrogenative coupling reactions. The reaction proceeds smoothly over a broad range of substrates with excellent functional group tolerance under mild conditions. Mechanistic studies suggest that the reaction is initiated by formamide radical or decarbonylative aminyl radical formation in the presence of TBHP, according to the different substituent on the N atom of formamide.
- Zhang, Yan,Zhang, Shiwei,Xu, Guangxing,Li, Min,Tang, Chunlei,Fan, Weizheng
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supporting information
p. 309 - 314
(2019/01/10)
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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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- Catalytic Selective Metal-Free Cross-Coupling of Heteroaromatic N-Oxides with Organosilanes
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A metal-free, regioselective C-H functionalization of heteroaromatic N-oxides has been developed. The method enables the synthesis of various benzylated and alkynylated N-heterocycles in a transition-metal-free manner employing organosilanes as coupling partners. The unanticipated reactivity has been exploited for the synthesis of a number of symmetrical disubstituted acetylenes from ethynyltrimethylsilane via carbon-silicon bond metathesis.
- Puthanveedu, Mahesh,Polychronidou, Vasiliki,Antonchick, Andrey P.
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supporting information
p. 3407 - 3411
(2019/05/10)
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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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- Simple and scalable electrochemical synthesis of 2,1-benzisoxazoles and quinoline: N -oxides
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Cathodic reduction of the nitro moiety and subsequent intramolecular cyclization affords different substituted 2,1-benzisoxazoles and quinoline N-oxides. This methodology allows the synthesis of two different types of heterocycles from common simple starting materials, using electrons as a sole reagent for this transformation. The electrolysis can be conducted in a very simple undivided electrolysis cell under constant current conditions. This permits working on a larger scale compared to other electrochemical methodologies and represents a significant advantage.
- Rodrigo, Eduardo,Baunis, Haralds,Suna, Edgars,Waldvogel, Siegfried R.
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p. 12255 - 12258
(2019/10/22)
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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 0036-0048
(2018/06/21)
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- A mild and efficient H2O2 oxygenation of N-heteroaromatic compounds to the amine N-oxides and KI deoxygenation back to the tertiary amine with hexaphenyloxodiphosphonium triflate
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A mild and efficient method for the oxidation of N-heteroaromatic compounds to the corresponding N-oxides using H2O2 in the presence of hexaphenyloxodiphosphnium triflate (Hendrickson reagent) in EtOH at room temperature was reported. This methodology presented relatively fast and selective reactions to afford the N-oxides in good yields. The reverse reactions, deoxygenation reactions, were also carried out under the same reaction conditions by KI to produce the tertiary amines.
- Khodaei, Mohammad Mehdi,Alizadeh, Abdolhamid,Hezarkhani, Hadis Afshar
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p. 1843 - 1849
(2018/07/06)
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- Combining C-H functionalisation and flow photochemical heterocyclic metamorphosis (FP-HM) for the synthesis of benzo[1,3]oxazepines
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C-H Activation/functionalisation and Flow Photochemical Heterocyclic Metamorphosis (FP-HM) have been combined to synthesize a library of benzo [1,3]oxazepines, a rarely described heterocyclic family. This combined protocol allows a range of arylated products to be made from simple starting materials, and the cheap flow photochemical system has proven effective for rapid synthesis of gram-quantities of benzo [1,3]oxazepines.
- Babra, Jasraj S.,Russell, Andrew T.,Smith, Christopher D.,Zhang, Yuxiong
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p. 5351 - 5357
(2018/05/31)
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- Structure-Activity Relationship for Small Molecule Inhibitors of Nicotinamide N-Methyltransferase
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Nicotinamide N-methyltransferase (NNMT) is a fundamental cytosolic biotransforming enzyme that catalyzes the N-methylation of endogenous and exogenous xenobiotics. We have identified small molecule inhibitors of NNMT with >1000-fold range of activity and developed comprehensive structure-Activity relationships (SARs) for NNMT inhibitors. Screening of N-methylated quinolinium, isoquinolinium, pyrididium, and benzimidazolium/benzothiazolium analogues resulted in the identification of quinoliniums as a promising scaffold with very low micromolar (IC50 à 1 μM) NNMT inhibition. Computer-based docking of inhibitors to the NNMT substrate (nicotinamide)-binding site produced a robust correlation between ligand-enzyme interaction docking scores and experimentally calculated IC50 values. Predicted binding orientation of the quinolinium analogues revealed selective binding to the NNMT substrate-binding site residues and essential chemical features driving protein-ligand intermolecular interactions and NNMT inhibition. The development of this new series of small molecule NNMT inhibitors direct the future design of lead drug-like inhibitors to treat several metabolic and chronic disease conditions characterized by abnormal NNMT activity.
- Neelakantan, Harshini,Wang, Hua-Yu,Vance, Virginia,Hommel, Jonathan D.,McHardy, Stanton F.,Watowich, Stanley J.
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supporting information
p. 5015 - 5028
(2017/06/28)
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- Intermolecular Amidation of Quinoline N-Oxides with Arylsulfonamides under Metal-Free Conditions
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An efficient method for the synthesis of N-(quinolin-2-yl)sulfonamides is described. The intermolecular amidation of quinoline N-oxides with sulfonamides proceeded smoothly in the presence of PhI(OAc)2 and PPh3 to afford N-(quinolin-
- Yu, Xiaoqiang,Yang, Sana,Zhang, Yue,Guo, Mingju,Yamamoto, Yoshinori,Bao, Ming
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supporting information
p. 6088 - 6091
(2017/11/27)
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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 0020-0023
(2017/08/25)
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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 0076; 0080; 0081; 0082
(2017/08/25)
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- O-bicyclic amine compounds as well as preparation method and chiral products thereof
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The invention relates to the field of asymmetric synthesis methods, and discloses a preparation method of o-bicyclic amine compounds. The method comprises the step of enabling a compound having a structure as shown in a formula (1) and hydrogen to be subjected to an addition reaction in presence of a chiral catalyst, wherein the chiral catalyst is a complex having a structure as shown in a formula (2). The invention also provides chiral products of the o-bicyclic amine compounds prepared by the method, and the o-bicyclic amine compounds. After the method is adopted, the selective hydrogenation reduction of the compound having the structure as shown in the formula (1) is realized by using the hydrogen, so that octahydrogenated products, i.e., the o-bicyclic amine compounds shown in a formula (4) are produced with low cost. The formula (1), the formula (2) and the formula (4) are described in the description.
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Paragraph 0214
(2017/11/04)
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- Design of a biased potent small molecule inhibitor of the bromodomain and PHD finger-containing (brpf) proteins suitable for cellular and in vivo studies
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The BRPF (bromodomain and PHD finger-containing) family are scaffolding proteins important for the recruitment of histone acetyltransferases of the MYST family to chromatin. Evaluation of the BRPF family as a potential drug target is at an early stage although there is an emerging understanding of a role in acute myeloid leukemia (AML). We report the optimization of fragment hit 5b to 13-d as a biased, potent inhibitor of the BRD of the BRPFs with excellent selectivity over nonclass IV BRD proteins. Evaluation of 13-d in a panel of cancer cell lines showed a selective inhibition of proliferation of a subset of AML lines. Pharmacokinetic studies established that 13-d had properties compatible with oral dosing in mouse models of disease (Fpo 49%). We propose that NI-42 (13-d) is a new chemical probe for the BRPFs suitable for cellular and in vivo studies to explore the fundamental biology of these proteins.
- Igoe, Niall,Bayle, Elliott D.,Fedorov, Oleg,Tallant, Cynthia,Savitsky, Pavel,Rogers, Catherine,Owen, Dafydd R.,Deb, Gauri,Somervaille, Tim C. P.,Andrews, David M.,Jones, Neil,Cheasty, Anne,Ryder, Hamish,Brennan, Paul E.,Müller, Susanne,Knapp, Stefan,Fish, Paul V.
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supporting information
p. 668 - 680
(2017/02/05)
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- 2,2′-Homocoupled Azine N,N′-Dioxides or Azine N-Oxides: CDC- or SNAr-Controlled Chemoselectivity
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An unprecedented Cu(OAc)2- and LiOtBu-mediated homocoupling of azine N-oxides to yield 2,2′-azine N,N′-dioxides is reported. This is the first instance in which copper has been used to catalyze the homodimerization reaction, especially of 2-phenylpyridine N-oxides. In the absence of catalytic copper, the reaction follows an alternative pathway, and instead of dioxides it yields 2,2′-azine N-monoxides. This latter protocol works efficiently with a range of N-heterocyclic oxides of pyridine, 2-phenylpyridine, quinoline and N-aryl-1,2,3-triazole. It is scalable, offers high regioselectivity and gives the products in moderate to high yields. The observed chemoselectivity between the copper-assisted and copper-free protocols is routed through oxidative cross-dehydrogenative coupling (CDC) and nucleophilic aromatic substitution of hydrogen (SNAr) pathways, respectively.
- Jha, Abadh Kishor,Jain, Nidhi
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p. 4765 - 4772
(2017/09/07)
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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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- Rhodium-Catalyzed Remote C-8 Alkylation of Quinolines with Activated and Unactivated Olefins: Mechanistic Study and Total Synthesis of EP4 Agonist
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Reported herein is a rhodium(III)-catalyzed regioselective distal C(sp2)-H bond alkylation of quinoline N-oxides using olefins as alkyl source and N-oxide as the traceless directing group. The reaction exhibits broad substrate scope with excellent selectivity for C-8 position and good yields of alkylated products. The usefulness of the developed catalytic protocol is established by synthesis of EP4 agonist. In mechanistic study, C-8 olefinated quinoline was identified as the reaction intermediate, which gets reduced to desired C-8 alkylated product in the presence of a rhodium(I) species (produced from rhodium(III) during reaction) and formic acid. Formic acid is produced from dimethylformamide in the presence of silver tetrafluoroborate. (Figure presented.).
- Sharma, Ritika,Kumar, Inder,Kumar, Rakesh,Sharma, Upendra
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supporting information
p. 3022 - 3028
(2017/09/08)
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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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- 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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- Renewable waste rice husk grafted oxo-vanadium catalyst for oxidation of tertiary amines to N-oxides
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Low cost renewable waste rice husks (RH) have been used as a support for grafting of an oxo-vanadium Schiff base via covalent attachment for the oxidation of tertiary amines to N-oxide. The synthesis of the desired RH grafted oxo-vanadium complex involves prior functionalization of the RH support with amino-propyltrimethoxysilane (APTMS) followed by its reaction with salicylaldehyde to get an RH-functionalized Schiff base which subsequently reacted with vanadyl sulphate to get the targeted oxo-vanadium catalyst. The synthesized catalyst was found to be an efficient heterogeneous catalyst and afforded an excellent yield of corresponding N-oxides via oxidation of tertiary amines with hydrogen peroxide as an oxidant. Furthermore, the synthesized catalyst was found to be quite stable and showed consistent activity for five runs without any loss in activity.
- Panwar, Vineeta,Bansal, Ankushi,Ray, Siddharth S.,Jain, Suman L.
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p. 71550 - 71556
(2016/08/05)
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- Catalyst and solvent-free alkylation of quinoline N-oxides with olefins: A direct access to quinoline-substituted α-hydroxy carboxylic derivatives
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A catalyst/solvent-free, one-pot and operationally simple method for the synthesis of quinoline-substituted α-hydroxy carboxylic derivatives by the hydroxyheteroarylation of olefins with quinoline N-oxides is reported. The reaction features a high atom-economy, mild and reagent/solvent-free conditions, broad substrate scope and good selectivity with high yields. A preliminary mechanistic study to shed light into the reaction pathway was also carried out.
- Kumar, Rakesh,Kumar, Inder,Sharma, Ritika,Sharma, Upendra
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supporting information
p. 2613 - 2617
(2016/03/05)
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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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- Synthesis and biological evaluation of quinoline derivatives as potential anti-prostate cancer agents and Pim-1 kinase inhibitors
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In this work, a series of quinoline derivatives were designed and synthesized as antitumor agents. Most quinolines showed potent anti-proliferative activity against human prostatic cancer PC-3 cell line. Among which, 9d, 9f and 9g were the most effective compounds with GI50 values of 2.60, 2.81 and 1.29 μM, respectively. Structure-activity relationship analysis indicated that the secondary amine linked quinoline and pyridine ring played an important role in the anti-proliferative effects. Mechanistic studies revealed that 9g was a potential Pim-1 kinase inhibitor with abilities of cell cycle arrest and apoptosis induction. Considering of the increased activity of Pim-1 in prostate cancer, such compounds have potential to be developed as anti-prostate cancer agents.
- Li, Kun,Li, Ying,Zhou, Di,Fan, Yinbo,Guo, Hongye,Ma, Tianyi,Wen, Jiachen,Liu, Dan,Zhao, Linxiang
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p. 1889 - 1897
(2016/04/05)
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- Synthesis of 2-Alkenylquinoline by Reductive Olefination of Quinoline N-Oxide under Metal-Free Conditions
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Synthesis of 2-alkenylquinoline by reductive olefination of quinoline N-oxide under metal-free conditions is disclosed. Practically, the reaction could be performed with quinoline as starting material via a one-pot, two-step process. A possible mechanism is proposed that involves a sequential 1,3-dipolar cycloaddition and acid-assisted ring opening followed by a dehydration process.
- Xia, Hong,Liu, Yuanhong,Zhao, Peng,Gou, Shaohua,Wang, Jun
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supporting information
p. 1796 - 1799
(2016/05/19)
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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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- 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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- Highly Enantioselective Direct Synthesis of Endocyclic Vicinal Diamines through Chiral Ru(diamine)-Catalyzed Hydrogenation of 2,2′-Bisquinoline Derivatives
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An asymmetric hydrogenation of 2,2′-bisquinoline and bisquinoxaline derivatives, catalyzed by chiral cationic ruthenium diamine complexes, was developed. A broad range of chiral endocyclic vicinal diamines were obtained in high yields with excellent diastereo- and enantioselectivity (up to 93:7 dl/meso and >99 % ee). These chiral diamines could be easily transformed into a new class of chiral N-heterocyclic carbenes (NHCs), which are important but difficult to access.
- Ma, Wenpeng,Zhang, Jianwei,Xu, Cong,Chen, Fei,He, Yan-Mei,Fan, Qing-Hua
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supporting information
p. 12891 - 12894
(2016/10/04)
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- Copper-Mediated [3+2] Annulation of 3-N-Hydroxyallylamines with Nitrosoarenes
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Cu-mediated annulations of N-hydroxyallylamines with nitrosoarenes proceed through unprecedented formal [3+2] cycloadditions of N-hydroxyaminoallyl radicals with nitrosoarenes. Our mechanistic analysis opposes a 5-endo-trig cyclization involved in the final ring-closure step. To manifest the reaction utility, chemical elaborations of resulting isoxazolidinyl products into 2- or 3-substituted quinoline N-oxides and acyclic 1,3-diamino-2-ols are also described. Radical initiative! Cu-mediated annulations of N-hydroxyallylamines with nitrosoarenes proceed through unprecedented formal [3+2] cycloaddition reactions (see scheme). To manifest the reaction utility, chemical elaborations of resulting isoxazolidinyl products into 2- or 3-substituted quinoline N-oxides and acyclic 1,3-diamino-2-ols have been described.
- Ghorpade, Satish,Jadhav, Prakash D.,Liu, Rai-Shung
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supporting information
p. 2915 - 2919
(2016/03/23)
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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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- Revealing the Macromolecular Targets of Fragment-Like Natural Products
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Fragment-like natural products were identified as ligand-efficient chemical matter for hit-to-lead development and chemical-probe discovery. Relying on a computational method using a topological pharmacophore descriptor and a drug database, several macromolecular targets from distinct protein families were expeditiously retrieved for structurally unrelated chemotypes. The selected fragments feature structural dissimilarity to the reference compounds and suitable target affinity, and they offer opportunities for chemical optimization. Experimental confirmation of hitherto unknown macromolecular targets for the selected molecules corroborate the usefulness of the computational approach and suggests broad applicability to chemical biology and molecular medicine. Target acquired: Hitherto unknown macromolecular targets of the fragment-like natural products goitrin, isomacroin, and graveolinine were discovered through the use of a computational target-prediction tool tailored for natural products. The results suggest that such methods will find application in target discovery for natural products and could inspire the design of new chemical entities for chemical biology and molecular medicine.
- Rodrigues, Tiago,Reker, Daniel,Kunze, Jens,Schneider, Petra,Schneider, Gisbert
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p. 10516 - 10520
(2015/09/02)
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- 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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supporting information
p. 3207 - 3210
(2015/03/30)
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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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