- β-Cyclodextrin as a scaffold for supramolecular chemistry, to reverse the regioselectivity of nitrile oxide cycloadditions
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β-Cyclodextrin has been used as a molecular scaffold, whereby tethering dipolarophiles to the cyclodextrin and then allowing preassociation of the modified cyclodextrins with aromatic nitrile oxides, as host-guest complexes, controls the relative orientations of the dipoles and the dipolarophiles in their cycloadditions. In this manner it has been possible to reverse the usual regioselectivity of cycloadditions of nitrile oxides, as illustrated by reactions with a terminal alkene, a terminal alkyne, and a 1,2-disubstituted alkene. For example, in aqueous solution, 4-tertbutylbenzonitrile oxide reacted with 6(A)-deoxy-6(A)-propynamido-β-cyclodextrin to give the corresponding 4- and 5-substituted isoxazoles, in a 15:1 ratio. With DMF as the solvent, to reduce the extent of host-guest complexation, the product ratio was 1:1.5. The role of complexation in these reactions is also demonstrated by contrasting these results with that of the reaction of the nitrile oxide with methyl propynoate, which afforded only the 5-substituted cycloaddition product. Molecular recognition by the cyclodextrin scaffolds was demonstrated through treatment of 4-tertbutylbenzonitrile oxide with an equimolar mixture of 6(A)-deoxy-6(A)-propynamido-β-cyclodextrin and methyl propynoate, in aqueous solution, which gave only the cycloadducts from reaction of the cyclodextrin dipolarophile.
- Meyer, Adam G.,Easton, Christopher J.,Lincoln, Stephen F.,Simpson, Gregory W.
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Read Online
- Anodic Oxidation of Aminotetrazoles: A Mild and Safe Route to Isocyanides
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A new electrochemical method for the preparation of isocyanides from easily accessible aminotetrazole derivatives has been developed, which tolerates an unprecedented range of functional groups. The use of chemical, rather than electrochemical, oxidation to afford isocyanides was also demonstrated, which provides access to these compounds for those without electrosynthesis equipment. The practicality of scale-up using flow electrochemistry has been demonstrated, in addition to the possibility of using electrochemically generated isocyanides in further reactions.
- Leech, Matthew C.,Petti, Alessia,Tanbouza, Nour,Mastrodonato, Andrea,Goodall, Iain C. A.,Ollevier, Thierry,Dobbs, Adrian P.,Lam, Kevin
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supporting information
p. 9371 - 9375
(2021/12/09)
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- Electrochemical synthesis of 1,2,4-oxadiazoles from amidoximes through dehydrogenative cyclization
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A convenient and efficient method for the generation of the iminoxy radical through anodic oxidation was developed for the synthesis of 3,5-disubstituted 1,2,4-oxadiazoles fromN-benzyl amidoximes. The transformation proceeds through 1.5-Hydrogen Atom Transfer (1,5-HAT) and intramolecular cyclization. The process features simple operation, mild conditions, broad substrate scope and high functional group compatibility, and provides a facile and practical way for the preparation of 1,2,4-oxadiazoles.
- Hu, Aixi,Jiang, chan,Li, mingfang,Xu, Leitao,Ye, Jiao,Yi, Yangjie
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supporting information
p. 10611 - 10616
(2021/12/27)
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- SO2F2-Mediated one-pot cascade process for transformation of aldehydes (RCHO) to cyanamides (RNHCN)
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A simple, mild and practical cascade process for the direct conversion of aldehydes to cyanamides was developed featuring a wide substrate scope and great functional group tolerability. This method allows for transformations of readily available, inexpensive, and abundant aldehydes to highly valuable cyanamides in a pot, atom, and step-economical manner with a green nitrogen source. This protocol will serve as a robust tool for the installation of the cyanamide moiety in various complicated molecules.
- Ding, Chengrong,Ge, Shuting,Wei, Junjie,Zhang, Guofu,Zhao, Yiyong
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p. 17288 - 17292
(2020/05/18)
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- Design, synthesis of novel 4,5-dihydroisoxazole-containing benzamide derivatives as highly potent FtsZ inhibitors capable of killing a variety of MDR Staphylococcus aureus
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Antibiotic resistance among clinically significant bacterial pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) is becoming a prevalent threat to public health, and new antibacterial agents with novel mechanisms of action hence are in an urgent need. As a part of continuing effort to develop antibacterial agents, we rationally designed and synthesized two series of 4,5-dihydroisoxazol-5-yl and 4,5-dihydroisoxazol-3-yl-containing benzamide derivatives that targeted the bacterial cell division protein FtsZ. Evaluation of their activity against a panel of Gram-positive and -negative pathogens revealed that compound A16 possessing the 4,5-dihydroisoxazol-5-yl group showed outstanding antibacterial activity (MIC, ≤0.125–0.5 μg/mL) against various testing strains, including methicillin-resistant, penicillin-resistant and clinical isolated S. aureus strains. Besides, further mouse infection model revealed that A16 could be effective in vivo and non-toxic to Hela cells. Finally, a detailed discussion of structure-activity relationships was conducted, referring to the docking results. It is worth noting that substituting a 4,5-dihydroisoxazole ring for the isoxazole ring not only broadened the antibacterial spectrum but also resulted in a significant increase in antibacterial activity against S. aureus strains. Taken together, these results suggest a promising chemotype for the development of new FtsZ-targeting bactericidal agents.
- Song, Di,Bi, Fangchao,Zhang, Nan,Qin, Yinhui,Liu, Xingbang,Teng, Yuetai,Ma, Shutao
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supporting information
(2020/09/11)
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- Vilsmeier-Haack reagent mediated synthetic transformations with an immobilized iridium complex photoredox catalyst
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An immobilized iridium complex photocatalyst Ir(ppy)2(PDVB-py) was synthesized by immobilization of the iridium complex onto the nanoporous vinylpyridine-divinylbenzene copolymer (PDVB-py). Its application for the synthesis of amides, nitriles, and anhydrides was reported via reactions under the action of the visible-light-driven in situ generated Vilsmeier-Haack reagent from CBr4 in DMF. The results showed that this heterogeneous photocatalyst has extremely high activity and excellent stability to be recycled five times.
- Zhi, Peng,Xi, Zi-Wei,Wang, Dan-Yan,Wang, Wei,Liang, Xue-Zheng,Tao, Fei-Fei,Shen, Run-Pu,Shen, Yong-Miao
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supporting information
p. 709 - 717
(2019/01/10)
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- Leaving Group Assisted Strategy for Photoinduced Fluoroalkylations Using N-Hydroxybenzimidoyl Chloride Esters
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Redox-active esters (RAEs) as alkyl radical precursors have been extensively developed for C?C bond formations. However, the analogous transformations of fluoroalkyl radicals from the corresponding acid or ester precursors remain challenging because of the high oxidation potential of the fluoroalkyl carboxylate anions. The newly developed N-hydroxybenzimidoylchloride (NHBC) ester provides a general leaving group assisted strategy to generate a portfolio of fluoroalkyl radicals, and can be successfully applied in photoinduced decarboxylative hydrofluoroalkylation and heteroarylation of unactivated olefins. In addition, DFT calculations revealed that the NHBC ester proceeds by the fluorocarbon radical pathway, whereas other well-known RAEs proceed by the nitrogen radical pathway.
- Zhang, Weigang,Zou, Zhenlei,Wang, Yuanheng,Wang, Yi,Liang, Yong,Wu, Zhengguang,Zheng, Youxuan,Pan, Yi
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supporting information
p. 624 - 627
(2018/12/13)
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- Betulinic acid derivatives: a new class of α-glucosidase inhibitors and LPS-stimulated nitric oxide production inhibition on mouse macrophage RAW 264.7 cells
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Chemical manipulation studies were conducted on betulinic acid (1), twenty-one new rationally designed analogues of 1 with modifications at C-28 were synthesized for their evaluation of inhibitory effects on α-glucosidase and LPS-stimulated nitric oxide production in mouse macrophage RAW 264.7 cells. Compound 2 (IC50 = 5.4 μM) exhibited an almost 1.4-fold increase in α-glucosidase inhibitory activity on yeast α-glucosidase while analogues 5 (IC50 16.4 μM) and 11 (IC50 16.6 μM) exhibited a 2-fold enhanced inhibitory activity on NO-production than betulinic acid.
- Gundoju, Narayanarao,Bokam, Ramesh,Yalavarthi, Nageswara Rao,Azad, Rajaram,Ponnapalli, Mangala Gowri
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supporting information
p. 2618 - 2622
(2018/04/30)
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- Continuous Platform to Generate Nitroalkanes On-Demand (in Situ) Using Peracetic Acid-Mediated Oxidation in a PFA Pipes-in-Series Reactor
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The synthetic utility of the aza-Henry reaction can be diminished on scale by potential hazards associated with the use of peracid to prepare nitroalkane substrates and the nitroalkanes themselves. In response, a continuous and scalable chemistry platform to prepare aliphatic nitroalkanes on-demand using the oxidation of oximes with peracetic acid and direct reaction of the nitroalkane intermediate in an aza-Henry reaction is reported. A uniquely designed pipes-in-series plug-flow tube reactor addresses a range of process challenges, including stability and safe handling of peroxides and nitroalkanes. The subsequent continuous extraction generates a solution of purified nitroalkane, which can be directly used in the following enantioselective aza-Henry chemistry to furnish valuable chiral diamine precursors with high selectivity, thus completely avoiding isolation of the potentially unsafe low-molecular-weight nitroalkane intermediate. A continuous campaign (16 h) established that these conditions were effective in processing 100 g of the oxime and furnishing 1.4 L of nitroalkane solution.
- Tsukanov, Sergey V.,Johnson, Martin D.,May, Scott A.,Kolis, Stanley P.,Yates, Matthew H.,Johnston, Jeffrey N.
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supporting information
p. 971 - 977
(2018/08/28)
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- Design, synthesis and structure-based optimization of novel isoxazole-containing benzamide derivatives as FtsZ modulators
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Antibiotic resistance among clinically significant bacterial pathogens is becoming a prevalent threat to public health, and new antibacterial agents with novel mechanisms of action hence are in an urgent need. Utilizing computational docking method and structure-based optimization strategy, we rationally designed and synthesized two series of isoxazol-3-yl- and isoxazol-5-yl-containing benzamide derivatives that targeted the bacterial cell division protein FtsZ. Evaluation of their activity against a panel of Gram-positive and -negative pathogens revealed that compounds B14 and B16 that possessed the isoxazol-5-yl group showed strong antibacterial activity against various testing strains, including methicillin-resistant Staphylococcus aureus and penicillin-resistant S. aureus. Further molecular biological studies and docking analyses proved that the compound functioned as an effective inhibitor to alter the dynamics of FtsZ self-polymerization via a stimulatory mechanism, which finally terminated the cell division and caused cell death. Taken together, these results could suggest a promising chemotype for development of new FtsZ-targeting bactericidal agent.
- Bi, Fangchao,Song, Di,Zhang, Nan,Liu, Zhiyang,Gu, Xinjie,Hu, Chaoyu,Cai, Xiaokang,Venter, Henrietta,Ma, Shutao
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- Ultrasonic-assisted synthesis of 1,4-disubstituted 1,2,3-triazoles via various terminal acetylenes and azide and their quorum sensing inhibition
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An efficient synthesis of 1,4-disubstituted 1,2,3-triazole derivatives was studied. 1,4-Disubstituted 1,2,3-triazoles containing isoxazole and thymidine structures were synthesized in 84–96% yields starting from various terminal isoxazole ether alkynes and β-thymidine azide derivatives via a 1,3-dispolar cycloaddition using copper acetate, sodium ascorbate as the catalyst under ultrasonic assisted condition. All the target compounds were characterized by HRMS, FT-IR, 1H NMR and 13C NMR spectroscopy. Furthermore, the quorum sensing inhibitory activities of synthesized compounds were evaluated with Chromobacterium violaceum (C. Violaceum CV026) based on their inhibition of violacein production, with compound C10-HSL as a positive control. The compounds 8a, 8c and 8f exhibited considerable levels of inhibitory activity against violacein production, and IC50 values were 217?±?19, 223?±?20 and 42.8?±?4.5?μM, respectively, which highlighted the potential of these compounds as lead structures for further research towards the development of novel QS inhibitors.
- Zhang, Da-wei,Zhang, Yu-min,Li, Jing,Zhao, Tian-qi,Gu, Qiang,Lin, Feng
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p. 343 - 353
(2016/12/23)
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- Asymmetric Nitrone Synthesis via Ligand-Enabled Copper-Catalyzed Cope-Type Hydroamination of Cyclopropene with Oxime
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We report realization of the first enantioselective Cope-type hydroamination of oximes for asymmetric nitrone synthesis. The ligand promoted asymmetric cyclopropene "hydronitronylation" process employs a Cu-based catalytic system and readily available starting materials, operates under mild conditions and displays broad scope and exceptionally high enantio- and diastereocontrol. Preliminary mechanistic studies corroborate a CuI-catalytic profile featuring an olefin metalla-retro-Cope aminocupration process as the key C-N bond forming event. This conceptually novel reactivity enables the first example of highly enantioselective catalytic nitrone formation process and will likely spur further developments that may significantly expedite chiral nitrone synthesis.
- Li, Zhanyu,Zhao, Jinbo,Sun, Baozhen,Zhou, Tingting,Liu, Mingzhu,Liu, Shuang,Zhang, Mengru,Zhang, Qian
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supporting information
p. 11702 - 11705
(2017/09/07)
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- An efficient solvent-free synthesis of isoxazolyl-1,4-dihydropyridines on solid support SiO2 under microwave irradiation
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An efficient synthesis of 1,4-dihydropyridines was developed. 1,4-Dihydropyridines were synthesized starting from various 3-substituted isoxazolyl-5-carbaldehydes, ethyl acetoacetate, and ammonium acetate under microwave irradiation and solvent-free conditions (86–96?%), and were characterized by HRMS, FT-IR, 1H NMR, and 13C NMR spectroscopy. Solid support SiO2 was found to possess favorable catalysis and dispersancy for the condensation reaction. The merits of the method included the environmental friendly reaction conditions, simple operation, extensive substrates, good yields and reuse of the SiO2. Moreover, the crystal structure of compound diethyl 4-[3-(2-methoxyphenyl)isoxazol-5-yl]-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate in orthorhombic Pbca space group was presented. Graphical abstract: [Figure not available: see fulltext.]
- Zhang, Dawei,Chen, Xiaodong,Guo, Xue,Zhang, Yumin,Hou, Yaya,Zhao, Tianqi,Gu, Qiang
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p. 1605 - 1614
(2016/08/16)
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- Highly efficient and stable peracid for rapid and selective oxidation of aliphatic amines to oximes
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A novel, transition-metal free, rapid approach for selective oxidation of aliphatic and benzylic amines to oximes is described. The dodecanebis(peroxoic acid)-DMF combination efficiently oxidizes various aliphatic amines at 50 °C temperature to give 100% conversion in 20 min with high oxime selectivity. The peroxy acid used here shows exceptional stability at room temperature and is non-shock sensitive in nature, which was confirmed by differential scanning colorimetric (DSC) analysis.
- Patil, Vilas V.,Gayakwad, Eknath M.,Shankarling, Ganapati S.
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p. 6677 - 6682
(2015/08/06)
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- Tandem and Selective Conversion of Tetrahydropyranyl and Silyl Ethers to Oximes Catalyzed with Trichloroisocyanuric Acid
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Direct and oxidative conversion of tetrahydropyranyl and silyl ethers to oximes is described using trichloroisocyanuric acid (TCCA) as a relatively stable and inexpensive oxidant surprisingly in a catalytic amount and hydroxylamine hydrochloride under solvent-free conditions. Oximes can be synthesized from these protected alcohols in the presence of some other functional groups with excellent chemoselectivity using the present tandem catalytic method.
- Aghapour, Ghasem,Abbaszadeh, Zeinab
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p. 1464 - 1470
(2015/09/01)
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- Efficient solvent-free synthesis of bis(indolyl)methanes on SiO2 solid support under microwave irradiation
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An efficient synthesis of bis(indolyl)methanes was developed. Bis(indolyl)methanes were synthesized starting from various aromatic aldehydes with indole under microwave irradiation and solvent-free conditions (85-98 %). Solid support SiO2 was found to possess favorable catalytic and dispersancy parameters for the condensation reaction. Moreover, novel bis(indolyl)methanes containing an isoxazole ring were synthesized via this method in excellent yields (> 94 %) using 3-substituted isoxazole-5-carbaldehydes and indole.
- Zhang, Da-Wei,Zhang, Yu-Min,Zhang, Yi-Liang,Zhao, Tian-Qi,Liu, Hong-Wei,Gan, Yuan-Ming,Gu, Qiang
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p. 470 - 478
(2015/01/30)
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- Efficient synthesis of bis-isoxazole ethers via 1,3-dipolar cycloaddition catalysed by Zn/Zn2+ and their antifungal activities
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An efficient method was developed for synthesising isoxazoles. A series of novel bis-isoxazole ether compounds VI, VII and VIII were synthesised starting from different substituted aldehydes (I) via a 1,3-dispolar cycloaddition using Zn/Zn2+ as a catalyst; these were characterised by FT-IR, HRMS, 1H NMR and 13C NMR spectroscopy. In addition, the antimicrobial properties of the synthesised products were investigated. The synthesised compounds exhibited significant antifungal activities in comparison with the standard drugs, fluconazole and itraconazole. It was found that Candida albicans was sensitive to 2-substituted phenyl bis-isoxazole ethers bearing pyridyl.
- Zhang, Da-Wei,Lin, Feng,Li, Bo-Chao,Liu, Hong-Wei,Zhao, Tian-Qi,Zhang, Yu-Min,Gu, Qiang
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p. 1500 - 1511
(2015/09/15)
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- Synthesis of Nitriles from Aldoximes and Primary Amides Using XtalFluor-E
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The dehydration reaction of aldoximes and amides for the synthesis of nitriles using [Et2NSF2]BF4 (XtalFluor-E) is described. Overall, the reaction proceeds rapidly (normally 1 h) at room temperature in an environmentally benign solvent (EtOAc) with only a slight excess of the dehydrating agent (1.1 equiv). A broad scope of nitriles can be prepared, including chiral nonracemic ones. In addition, in a number of cases, further purification of the nitrile after the workup was not required.
- Keita, Massaba,Vandamme, Mathilde,Paquin, Jean-Fran?ois
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p. 3758 - 3766
(2015/11/28)
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- Conversion of aldoximes into nitriles and amides under mild conditions
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A series of Pd(en)X2 salts were used as catalysts for the conversion of aldoximes into nitriles and amides. Highlights of this protocol include the use of inexpensive polar solvents, including water, and moderate reaction temperatures. A high degree of selectivity in the reaction outcome was observed when using aliphatic vs. aromatic/conjugated aldoximes. The Royal Society of Chemistry 2013.
- Tambara, Koujiro,Pantos, G. Dan
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supporting information
p. 2466 - 2472
(2013/06/05)
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- Design, synthesis, and herbicidal activities of novel 2-cyanoacrylates containing isoxazole moieties
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A series of novel 2-cyanoacrylates containing an isoxazole moiety were designed and synthesized. Their structures were characterized by 1H NMR and elemental analysis (or high-resolution mass spectrometry). Their herbicidal activities against four species were evaluated, and the results indicated that some of the title compounds showed excellent herbicidal activities against rape and amaranth pigweed in postemergence treatment even at a dose of 75 g/ha.
- Liu, Yuxiu,Cui, Zhipeng,Liu, Bin,Cai, Baoli,Li, Yonghong,Wang, Qingmin
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scheme or table
p. 2685 - 2689
(2011/07/07)
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- Synthesis of 5-isoxazol-5-yl-2′-deoxyuridines exhibiting antiviral activity against HSV and several RNA viruses
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This paper describes a simple method for synthesizing a small library of 5-isoxazol-5-yl-2′-deoxyuridines from 5-iodo-2′-deoxyuridine. Nitrile oxides were generated in situ from oximes using a commercial bleaching agent; their cycloaddition with 5-ethynyl-2′-deoxyuridine yielded isoxazoles possessing activity against herpes simplex viruses 1 and 2, Encephalomyocarditis virus, Coxsackie B3, and vesicular stomatitis virus; these isoxazoles were, however, inactive against corona virus, influenza virus, and HIV.
- Lee, Yoon-Suk,Park, Sun Min,Kim, Byeang Hyean
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scheme or table
p. 1126 - 1128
(2009/08/07)
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- AZOLE-BASED PHOSPHODIESTERASE INHIBITORS
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The present invention relates to phosphodiesterase (PDE) type IV selective inhibitors. Processes for the preparation of disclosed compounds of Formula (I), pharmaceutical compositions containing the compounds described herein and their use as PDE type IV selective inhibitors are provided.
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Page/Page column 48
(2010/11/24)
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- Synthesis and tyrosinase inhibitory activity of novel N-hydroxybenzyl-N-nitrosohydroxylamines
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Several novel N-substituted N-nitrosohydroxylamines were synthesized. They all inhibited mushroom tyrosinase, but the type of inhibition was different depending on the substituent. Some N-(mono- or dihydroxybenzyl)-N-nitrosohydroxylamines exhibited uncompetitive inhibition with respect to L-dopa. Among them, compound 6 was also a competitive inhibitor with respect to oxygen. This observation suggests that another interaction by the meta- or para-hydroxyl group might stabilize the binding of the inhibitor to the enzyme through the oxygen binding site.
- Shiino, Mitsuhiro,Watanabe, Yumi,Umezawa, Kazuo
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p. 129 - 135
(2007/10/03)
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- One-pot oxidation of azomethine compounds into arenecarboxylic acids
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Aromatic azomethine compounds, such as aldazines 1, aldoximes 7 and tosylhydrazones 8 oxidized with 30% hydrogen peroxide in the presence of poly(bis-1,2-phenylene) diselenide (6) as catalyst produce arenecarboxylic acids 2 mostly in high to excellent yields. The presented one-pot procedure has a synthetic value.
- Giurg,Said,Syper,Mlochowski
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p. 3151 - 3159
(2007/10/03)
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