- Enthalpies of combustion of 2,4,6-trimethylbenzonitrile, 2,4,6-trimethylbenzonitrile N-oxide, 2,6-dimethylbenzonitrile, 2,4,6-trimethoxybenzonitrile, and 2,4,6-trimethoxybenzonitrile N-oxide: the dissociation ethalpies of the (N-O) bonds
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The standard (pdeg = 0.1 MPa) molar enthalpies of combustion at 298.15 K were measured by static-bomb calorimetry and the standard molar enthalpies of sublimation at 298.15 K were measured by microcalorimetry for the following aromatic nitriles and aromatic nitrile N-oxides: .From the standard molar enthalpies of formation of the gaseous compounds, the molar dissociation enthalpies of the (N-O) bonds were derived: D(N-O)/(kJ*mol-1): trimethylbenzonitrile N-oxide, (222.2 +/- 4.6); trimethoxybenzonitrile N-oxide, (232.8 +/- 3.8).
- Acree, W. E.,Tucker, Sheryl A.,Zvaigzne, Anita I.,Meng-Yan, Yang,Pilcher, G.,Ribeiro da Silva, Maria D. M. C.
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Read Online
- N-Arylalkyl-N-phenylhydroxylamines as novel photo-induced DNA-cleaving agents
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Single-strand cleavage of DNA was accomplished by photolysis of various N-arylalkyl-N-phenylhydroxylamines under aerobic conditions for 3 h with 312 nm UV light, which functioned as the trigger to initiate the new and controllable DNA cleavage process.
- Hwu,Tsay,Chen,Patel,Chou
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Read Online
- Gold-Catalyzed Bicyclic and [3+2]-Annulations of Internal Propargyl Alcohols with Nitrones and Imines To Yield to Two Distinct Heterocycles
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A gold-catalyzed synthesis of 1,3-dihydrooxazolo[3,4-a]indoles from 1-oxo-3-yn-4-ols and nitrones is described; this new bicyclic annulation presents the first examples that internal alkynes can react with nitrones to undergo an oxoarylation route. DFT calculations indicate a [3,3]-sigmatropic shift of initial alkenylgold intermediates to elude the intermediacy of gold carbenes. We also developed new [3+2]-annulations of the same 1-oxo-3-yn-4-ols with imines, yielding oxazolidin-4-ylidene derivatives efficiently. The tethered alcohols of these 1-oxo-3-ynes allow trapping of their metastable 2-azadienium intermediates to enable a novel annulation. Our mechanistic analysis indicates that the two products, despite their structural relevance, are produced from two independent systems. (Figure presented.).
- More, Sayaji Arjun,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
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supporting information
p. 525 - 531
(2020/12/01)
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- Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement
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Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
- Cheng, Mu-Jeng,Kardile, Rahul Dadabhau,Kuo, Tung-Chun,Liu, Rai-Shung,More, Sayaji Arjun
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supporting information
p. 5506 - 5511
(2021/07/31)
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- Hydrazones as Substrates in the Synthesis of Isoxazolidines via a KOH-Promoted One-Pot Three-Component Cycloaddition with Nitroso Compounds and Olefins
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Hydrazones have been employed as the starting materials in a KOH-mediated one-pot three-component cycloaddition with readily accessible nitroso compounds and olefins to construct various isoxazolidines. Compared with diazo compounds as starting materials, this methodology could afford a wider range of products in good to excellent yields and diastereoselectivities for most substrates, and hydrazones are cheaper, more accessible, and safer substrates. The experimental study shows that the choice of suitable hydrazones is crucial.
- Chen, Wenwen,Li, Wenhui,Li, Xing,Lin, Jianying,Wei, Wen-Long,Zhai, Pingan
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p. 17710 - 17721
(2021/12/09)
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- S -Tetrazine: Robust and Green Photoorganocatalyst for Aerobic Oxidation of N,N-Disubstituted Hydroxylamines to Nitrones
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Efficient photocatalytic aerobic oxidative dehydrogenation reactions of N,N-disubstituted hydroxylamines to nitrones were developed with an in situ generated photocatalyst based on commercially available 3,6-dichlorotetrazine. This process affords a wide range of nitrones in high yields under mild conditions. In addition, an oxidative (3+3) cycloaddition between an oxyallyl cation precursor and a hydroxylamine was also developed.
- Allain, Clémence,Audebert, Pierre,Claraz, Aurélie,Le, Tuan,Lyu, Jiyuan,Masson, Géraldine
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supporting information
(2021/12/06)
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- Polyfunctionalized biaryls accessed by a one-pot nucleophilic aromatic substitution and sigmatropic rearrangement reaction cascade under mild conditions
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A practical synthetic method has been developed for polyfunctionalized biaryls based on a facile one-pot nucleophilic aromatic substitution (SNAr) reaction and [5,5]- or [3,3]-sigmatropic rearrangement reaction cascade. Under mild basic conditions, N-arylhydroxylamines reacted with o-activated fluoro (het)arenes to form N,O-diarylhydroxylamine intermediates which underwent spontaneously selective [5,5]-sigmatropic rearrangement reaction to produce diverse functionalized 4-amino-4′-hydroxy-1,1′-biaryls. A sequential SNAr reaction and [3,3]-sigmatropic rearrangement took place between N-arylhydroxylamines and 2-fluoropyridine derivatives or 4-fluorobenzonitrile to afford functionalized 2-amino-2′-hydroxy-1,1′-biaryls. As invaluable and unique building blocks, the resulting biaryls were applied in the straightforward synthesis of N2,O2-coronarene, carbazole, aza- and diaza carbazole derivatives.
- Liang, Dong-Dong,Guo, Shen-Yi,Tong, Shuo,Wang, Mei-Xiang
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- Method for converting terminal alkyne into carboxylic acid and application of method in construction of gene coding library
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The invention provides a method for converting terminal alkyne into carboxylic acid in construction of a gene coding compound library. The method has the advantages of good universality, mild conditions, convenient operation and high yield, and is suitable for synthesis of the gene coding compound library by a porous plate. According to the method for converting terminal alkyne into carboxylic acid in construction of the gene coding compound library, the reaction types which can be successfully applied in the gene coding library technology are increased, and the synthesis method of the gene coding compound library is simplified.
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Paragraph 0056-0058
(2021/11/27)
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- Method for converting terminal alkyne into amide and application of method in construction of gene coding library
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The invention provides a method for converting terminal alkyne into amide on oligomeric nucleic acid, and has good universality. The method is mild in condition, convenient to operate and high in yield, and is suitable for synthesis of a gene coding compound library carried out on a porous plate. The invention increases the reaction type which can be successfully applied in the gene coding library technology, and particularly provides a method for directly carrying out amide coupling reaction of free carboxylic acid and an unprotected primary or secondary amine small molecule compound. Thus, the synthesis step of the gene coding compound library is simplified, and the synthesis efficiency of the gene coding compound library and the quality of the oligomeric nucleic acid product are improved.
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Paragraph 0057-0059
(2021/12/07)
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- Single-Step Approach toward Nitrones via Pyridinium Ylides: The DMAP-Catalyzed Reaction of Benzyl Halides with Nitrosoarenes
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A single-step approach is reported for the preparation of nitrones from benzyl halides and nitrosoarenes via pyridinium ylides, utilizing 4-dimethylaminopyridine (DMAP) catalyst and mild reaction conditions (Li2CO3, dimethylacetamide, and room temperature). The reaction provides both keto-and aldonitrones in high yields with a wide scope for benzyl halides and nitrosoarenes. In the same reaction system, 2-methyl-2-nitrosopropane, which does not have an aryl group, also affords the corresponding N-tert-butyl nitrones from primary benzyl bromides that have an electron-withdrawing group. As an application of the reaction, methyl 2-bromo-2-phenylacetate was used to prepare the corresponding isoxazolidine by a sequential one-pot synthesis.
- Jung, Yeonghun,Hong, Jee Eun,Kwak, Jae-Hwan,Park, Yohan
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p. 6343 - 6350
(2021/05/29)
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- Regio- and Enantioselective (3+3) Cycloaddition of Nitrones with 2-Indolylmethanols Enabled by Cooperative Organocatalysis
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The regio- and enantioselective (3+3) cycloaddition of nitrones with 2-indolylmethanols was accomplished by the cooperative catalysis of hexafluoroisopropanol (HFIP) and chiral phosphoric acid (CPA). Using this approach, a series of indole-fused six-membered heterocycles were synthesized in high yields (up to 98 %), with excellent enantioselectivities (up to 96 % ee) and exclusive regiospecificity. This approach enabled not only the first organocatalytic asymmetric (3+3) cycloaddition of nitrones but also the first C3-nucleophilic asymmetric (3+3) cycloaddition of 2-indolylmethanols. More importantly, theoretical calculations elucidated the role of the cocatalyst HFIP in helping CPA control the reactivity and enantioselectivity of the reaction, demonstrating a new mode of cooperative catalysis.
- Li, Tian-Zhen,Liu, Si-Jia,Sun, Yu-Wen,Deng, Shuang,Tan, Wei,Jiao, Yinchun,Zhang, Yu-Chen,Shi, Feng
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supporting information
p. 2355 - 2363
(2020/12/09)
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- Gold-Catalyzed Oxidative Aminocyclizations of Propargyl Alcohols and Propargyl Amines to Form Two Distinct Azacyclic Products: Carbene Formation versus a 3,3-Sigmatropic Shift of an Initial Intermediate
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Gold-catalyzed oxidations of propargyl alcohols with nitrones by using a P(tBu)2(o-biphenyl)Au+ catalyst, afforded bicyclic annulation products from the Mannich reactions of gold enolates. The same reactions of propargyl amines with nitrones by using the same gold catalyst gave distinct oxoarylation products. Our DFT calculations indicate that oxidation of propargyl alcohols with nitrones by using electron-rich gold catalysts lead only to gold carbenes, which can generate gold enolates or oxoarylation intermediates with enolate species having a barrier smaller than that of oxoarylation species.
- Chao, Tzu-Hsuan,Chen, Mu-Jeng,Liu, Rai-Shung,Raj, Antony Sekar Kulandai,Sasane, Amit Vijay
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supporting information
p. 16932 - 16938
(2020/11/30)
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- Facile approach to alkaloid-like 6/6/5/5-tetracyclic spiroheterocycles via 1,3-dipolar cycloaddition reaction of fused 1H-pyrrole-2,3-diones with nitrones
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A facile synthetic approach towards 6/6/5/5-tetracyclic spiroheterocycles has been developed from the highly diastereoselective 1,3-dipolar cycloaddition reaction of [e]-fused 1H-pyrrole-2,3-diones with nitrones. The described novel heterocyclic systems are heteroanalogs of cytotoxic alkaloids, kibalaurifoline and gitingensine. The developed reaction represents the first example of involvement of 1H-pyrrole-2,3-diones fused at [e]-side in a 1,3-dipolar cycloaddition reaction.
- Stepanova, Ekaterina E.,Dmitriev, Maksim V.,Maslivets, Andrey N.
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supporting information
(2020/01/22)
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- Optimized aqueous Kinugasa reactions for bioorthogonal chemistry applications
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Kinugasa reactions hold potential for bioorthogonal chemistry in that the reagents can be biocompatible. Unlike other bioorthogonal reaction products, β-lactams are potentially reactive, which can be useful for synthesizing new biomaterials. A limiting factor for applications consists of slow reaction rates. Herein, we report an optimized aqueous copper(i)-catalyzed alkyne-nitrone cycloaddition involving rearrangement (CuANCR) with rate accelerations made possible by the use of surfactant micelles. We have investigated the factors that accelerate the aqueous CuANCR reaction and demonstrate enhanced modification of a model membrane-associated peptide. We discovered that lipids/surfactants and alkyne structure have a significant impact on the reaction rate, with biological lipids and electron-poor alkynes showing greater reactivity. These new findings have implications for the use of CuANCR for modifying integral membrane proteins as well as live cell labelling and other bioorthogonal applications.
- Bilodeau, Didier A.,Margison, Kaitlyn D.,Ahmed, Noreen,Strmiskova, Miroslava,Sherratt, Allison R.,Pezacki, John Paul
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supporting information
p. 1988 - 1991
(2020/02/25)
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- Synthesis of 2′,3′,4′-triaryl-5,6-dihydro-8H-spiro[indolizine-7,5′-isoxazolidin]-8-ones via 1,3-dipolar cycloaddition reaction involving (Z)-C-aryl-N-phenylnitrones
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[Figure not available: see fulltext.] The 1,3-dipolar cycloaddition of C-aryl-N-phenylnitrones to 7-arylmethylidene-6,7-dihydroindolizin-8(5H)-ones afforded novel 2′,3′,4′-triaryl-5,6-dihydro-8H-spiro[indolizine-7,5′-isoxazolidin]-8-ones in moderate yield
- Li, Xiaofang,Li, Youfeng,Tang, Jin
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p. 1062 - 1066
(2020/10/02)
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- Nitrone synthesis via pair electrochemical coupling of Nitro-Compounds with Benzyl Alcohol Derivatives
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Here we report a paired electrochemical coupling of readily accessible nitro-compounds with benzyl alcohols to yield nitrone derivatives. In this work, electrochemical behavior of nitrobenzene and benzyl alcohol derivatives was studied by cyclic voltammetry and controlled potential coulommetry. Electrochemical reactions have been performed in aqueous/ethanol (or acetonitrile) solutions by employing common graphite electrodes and a simple controlled current protocol which can make this strategy more appealing than other conventional pathways.
- Salehzadeh, Hamid,Mashhadizadeh, Mohammad Hossein
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p. 9307 - 9312
(2019/07/08)
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- Metal-free synthesis of triarylated (: Z)-nitrones via H2O-mediated 1,3-dipolar transfer under aerobic conditions
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A new and environmentally benign protocol aimed at the generation of triarylated (Z)-nitrones in generally good yields has been developed via metal- and catalyst-free H2O-mediated 1,3-dipolar transfer reaction of para-quinone methides (p-QMs) with diarylated nitrones under aerobic conditions. The purification of these products only needs to be recrystallized by a mixed solvent comprising small amounts of petroleum ether and ethyl acetate, thereby avoiding the requirement of traditional chromatography. This new 1,3-dipolar strategy features broader substrate scope, green process, and mild conditions.
- Chen, Ke,Hao, Wen-Juan,Tu, Shu-Jiang,Jiang, Bo
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p. 675 - 683
(2019/02/14)
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- A highly efficient and stereoselective cycloaddition of nitrones to N-arylitaconimides
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The 1,3-dipolar cycloaddition of keto- and aldonitrones with N-arylitaconimides proceeds regioselectively giving only 5-spiroisoxazolidines. In the case of aldonitrones the reaction proceeds with high diastereoselectivity. A range of the obtained adducts
- Teterina, Polina S.,Efremova, Mariia M.,Sirotkina, Ekaterina V.,Novikov, Alexander S.,Khoroshilova, Olesya V.,Molchanov, Alexander P.
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supporting information
(2019/08/26)
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- Highly Electron-Deficient Pyridinium-Nitrones for Rapid and Tunable Inverse-Electron-Demand Strain-Promoted Alkyne-Nitrone Cycloaddition
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Highly accelerated inverse-electron-demand strain-promoted alkyne-nitrone cycloaddition (IED SPANC) between a stable cyclooctyne (bicyclo[6.1.0]nonyne (BCN)) and nitrones delocalized into a Cα-pyridinium functionality is reported, with the most
- Gunawardene, Praveen N.,Luo, Wilson,Polgar, Alexander M.,Corrigan, John F.,Workentin, Mark S.
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supporting information
p. 5547 - 5551
(2019/08/01)
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- Strain-Release Driven Cycloadditions for Rapid Construction of Functionalized Pyridines and Amino Alcohols
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This paper describes the development of a new variant of stereoselective strain-release driven reactions (formal homo [3 + 2] dipolar cycloadditions) which utilize housane (1) to construct functionalized amino alcohols and pyridine-substituted cyclopentanes in two to three steps from simple and easily available building blocks (nitrones and pyridine N-oxides respectively).
- Clementson, Sebastian,Radaelli, Alessio,Fjelbye, Kasper,Tanner, David,Jessing, Mikkel
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supporting information
p. 4763 - 4766
(2019/06/24)
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- Synthesis of Exclusively 4-Substituted β-Lactams through the Kinugasa Reaction Utilizing Calcium Carbide
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A new Kinugasa reaction protocol has been elaborated for the one-pot synthesis of 4-substituted β-lactams utilizing calcium carbide and nitrone derivatives. Calcium carbide is thereby activated by TBAF·3H2O in the presence of CuCl/NMI. The ease of synthesis and use of inexpensive chemicals provides rapid access of practical quantities of β-lactams exclusively substituted at position 4.
- Hosseini, Abolfazl,Schreiner, Peter R.
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supporting information
p. 3746 - 3749
(2019/05/24)
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- Visible-light-initiated one-pot clean synthesis of nitrone from nitrobenzene and benzyl alcohol over CdS photocatalyst
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The controlled visible-light mediated conversion of nitroaromatics to versatile nitrogen-containing intermediates is of great significance but still remains a challenge. Herein, we report for the first time a facile visible-light-initiated one-pot strategy for clean and efficient synthesis of nitrone from nitrobenzene and benzyl alcohol. It integrates the controlled photocatalytic reduction of nitrobenzene to phenylhydroxylamine by photogenerated electrons with the selective photocatalytic oxidation of benzyl alcohol to benzaldehyde by photoinduced holes over a low-cost CdS photocatalyst with a suitable reduction capability, followed by spontaneous condensation of the as-formed hydroxylamine and aldehyde at ambient pressure and room temperature. Furthermore, by modulating cocatalyst and illumination time, for the conversion of the same reactants, the other two useful nitrogen-containing compounds, imine and secondary amine, were also successfully synthesized. The reaction mechanisms for flexible synthesis of the three target products are proposed.
- Yu, Weiwei,Guo, Xinwen,Song, Chunshan,Zhao, Zhongkui
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- Synthesis and Antimicrobial Evaluation of New Pyrrolo-isoxazolidine Derivatives
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In the present study, pyrrolo-isoxazolidines 3(a-l) and 4(a-e), 4g, 4i, 4j have been synthesized by using the 1,3-dipolar cycloaddition reactions of nitrones 1(a-l) with ester substituted N-aryl maleimide (2b). These heterocycles have been obtained in cis and trans diastereomeric forms. The structures of newly synthesized heterocycles have been confirmed from their spectroscopic parameters such as IR,1H NMR,13C NMR and ESI-MS. The in vitro antimicrobial evaluation of these compounds were also investigated. Most of the prepared heterocycles showed significant antimicrobial properties. C3-phenyl substituted products exhibited the remarkable antibacterial behaviours while C3-thienyl/furyl substituted heterocycles proved themselves potent antifungal agents.
- Yusuf, Mohamad,Shehneela,Singh, Baldev
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p. 220 - 228
(2018/12/11)
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- Tandem Chiral Cu(II) Phosphate-Catalyzed Deoxygenation of Nitrones/Enantioselective Povarov Reaction with Enecarbamates
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A new catalytic enantioselective tandem deoxygenation/aza-Diels-Alder reaction of nitrones with enecarbamates was serendipitously discovered in the presence of chiral copper(II) diphosphate complexes. This process affords a wide range of 4-aminotetrahydroquinolines in respectable yields under mild conditions with good to excellent ee values.
- Gelis, Coralie,Levitre, Guillaume,Guérineau, Vincent,Touboul, David,Neuville, Luc,Masson, Géraldine
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p. 5151 - 5155
(2019/06/27)
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- A green synthesis of nitrones in glycerol
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Abstract: An eco-friendly and efficient synthesis of nitrones is presented by condensation of an equimolar amount of aldehydes and N-substituted hydroxylamine hydrochlorides in glycerol as a recyclable solvent-catalyst. This novel protocol provides rapid and mild access to a series of nitrone derivatives in good to excellent yields in the absence of catalyst and base. Graphic abstract: SYNOPSIS In this study, a base-free protocol by using glycerol as the solvent-catalyst was applied for an eco-friendly synthesis of nitrones from the condensation of aldehydes and N-substituted hydroxylaminehydrochlorides.[Figure not available: see fulltext.].
- Shariatipour, Monire,Jadidinejad, Masoumeh,Heydari, Akbar
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- Catalytic Diastereo- and Enantioselective Synthesis of 2-Imidazolinones
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Chiral cyclic ureas (2-imidazolinones) were prepared by the reaction of nitrones and isocyanoacetate esters using a multicatalytic system that combines a bifunctional Br?nsted base-squaramide organocatalyst and Ag+ as a Lewis acid. The reaction could be achieved with a range of nitrones derived from aryl- and cycloalkylaldehydes with moderate diastereo- and good enantioselectivity. A plausible mechanism involving an initial formal [3 + 3] cycloaddition of the nitrone and isocyanoacetate ester, followed by rearrangement to an aminoisocyanate and cyclization to the imidazolinone, is proposed.
- Martínez-Pardo, Pablo,Blay, Gonzalo,Escrivá-Palomo, Alba,Sanz-Marco, Amparo,Vila, Carlos,Pedro, José R.
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supporting information
p. 4063 - 4066
(2019/06/17)
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- Catalytic Transformations of Alkynes into either α-Alkoxy or α-Aryl Enolates: Mannich Reactions by Cooperative Catalysis and Evidence for Nucleophile-Directed Chemoselectivity
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The catalytic formation of gold enolates from alkynes, nitrones, and nucleophiles is described, and their Mannich reactions result in nucleophile-directed chemoselectivity through cooperative catalysis. For 1-alkyn-4-ols and 2-ethynylphenols, their gold-catalyzed nitrone oxidations afforded N-containing dihydrofuran-3(2H)-ones with syn selectivity. The mechanism involves the Mannich reactions of gold enolates with imines through an O-H-N hydrogen-bonding motif. For aryloxyethynes, their gold enolates react selectively with nitrones to deliver 3-alkylidenebenzofuran-2-ones, as controlled by a C-H-O hydrogen-bonding motif.
- Sahani, Rajkumar Lalji,Patil, Manoj D.,Wagh, Sachin Bhausaheb,Liu, Rai-Shung
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supporting information
p. 14878 - 14882
(2018/10/15)
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- Trifluoromethyl Vinyl Sulfide: A Building Block for the Synthesis of CF3S-Containing Isoxazolidines
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Trifluoromethyl vinyl sulfide, a potential building block for pharmaceutically and agrochemically relevant products, is prepared and used for the first time in high-pressure-mediated 1,3-dipolar cycloaddition reactions with nitrones to synthesize (trifluoromethyl)sulfanyl isoxazolidines.
- Riesco-Domínguez, Alejandra,Van De Wiel, Jeroen,Hamlin, Trevor A.,Van Beek, Bas,Lindell, Stephen D.,Blanco-Ania, Daniel,Bickelhaupt, F. Matthias,Rutjes, Floris P. J. T.
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p. 1779 - 1789
(2018/02/23)
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- Copper-Catalyzed Synthesis of Polysubstituted Pyrroles through [3+1+1] Cycloaddition Reaction of Nitrones and Isocyanides
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An efficient, copper-catalyzed [3+1+1] cycloaddition reaction was developed for the expedient synthesis of pharmacologically interesting polysubstituted pyrroles from easily available nitrones and α-acidic isocyanides. The given approach features a new mo
- Tian, Zhuang,Xu, Jiaojiao,Liu, Bingxin,Tan, Qitao,Xu, Bin
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supporting information
p. 2603 - 2606
(2018/05/22)
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- Metal-free approach for the ?-proline mediated synthesis of nitrones from nitrosobenzene
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An efficient, and metal-free approach for the ?-proline mediated synthesis of nitrones from nitrosobenzene and benzaldehydes has been established. The reaction undergoes very efficiently at room temperature in methanol as a solvent. The reaction is assumed to involve that the initial formation of azomethine ylide and [2 + 3] cycloaddition of nitrosobenzene, followed by the subsequent retro [2 + 3] cycloaddition could offer the desired nitrone.
- Choi, Minho,Viji, Mayavan,Kim, Donghwan,Lee, Young Hee,Sim, Jaeuk,Kwak, Young-Shin,Lee, Kiho,Lee, Heesoon,Jung, Jae-Kyung
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p. 4182 - 4187
(2018/06/19)
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- Br?nsted acid-catalyzed metal- and solvent-free quinoline synthesis from: N -alkyl anilines and alkynes or alkenes
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Br?nsted acid-catalyzed cyclization reactions of N-alkyl anilines with alkynes or alkenes in the presence of oxygen gas as an oxidant under metal- and solvent-free conditions are described. Various quinoline derivatives are obtained in satisfactory to exc
- Ahmed, Waqar,Zhang, Sheng,Yu, Xiaoqiang,Yamamoto, Yoshinori,Bao, Ming
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supporting information
p. 261 - 265
(2018/01/17)
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- A Revised Mechanism for the Kinugasa Reaction
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Detailed kinetic analysis for the Cu(I)-catalyzed Kinugasa reaction forming β-lactams has revealed an anomalous overall zero-order reaction profile, due to opposing positive and negative orders in nitrone and alkyne, respectively. Furthermore, the reaction displays a second-order dependence on the catalyst, confirming the critical involvement of a postulated bis-Cu complex. Finally, reaction progress analysis of multiple byproducts has allowed a new mechanism, involving a common ketene intermediate to be delineated. Our results demonstrate that β-lactam synthesis through the Kinugasa reaction proceeds via a cascade involving (3 + 2) cycloaddition, (3 + 2) cycloreversion, and finally (2 + 2) cycloaddition. Our new mechanistic understanding has resulted in optimized reaction conditions to dramatically improve the yield of the target β-lactams and provides the first consistent mechanistic model to account for the formation of all common byproducts of the Kinugasa reaction.
- Malig, Thomas C.,Yu, Diana,Hein, Jason E.
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supporting information
p. 9167 - 9173
(2018/07/15)
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- RUBBER COMPOSITION FOR TIRE TREAD, AND STUDLESS TIRE
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The present invention is to provide a rubber composition for a tire tread, which can produce a studless tire having both excellent performance on ice and excellent wear resistance, and to provide a studless tire using the rubber composition. The rubber composition for a tire tread of the present invention contains 100 parts by mass of a diene rubber (A) containing a modified butadiene rubber and from 0.5 to 25 parts by mass of thermally expandable microcapsules (B). The modified butadiene rubber is obtained by modifying an unmodified butadiene rubber with a carboxy group-containing nitrone compound. The content of the modified butadiene rubber in the diene rubber (A) is from 20 to 65 mass %.
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Paragraph 0182
(2018/05/16)
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- Coupling of N -Nosylhydrazones with Nitrosoarenes: Transition-Metal-Free Approach to (Z)- N -Arylnitrones
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An efficient and transition-metal-free protocol for the synthesis of (Z)- N -arylnitrones from the direct coupling of N -nosylhydrazones with nitrosoarenes under mild conditions is described. The protocol is compatible with a wide range of functional groups placed on both the reagents and provided the corresponding nitrones in good to excellent yields by simple recrystallization process. The use of these 1,3-dipoles for the synthesis of substituted indoles is elaborated for 2,3-diphenyl-1 H -indole.
- Liu, Tingting,Liu, Zhaohong,Liu, Zhenhua,Hu, Donghua,Wang, Yeming
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p. 1728 - 1736
(2018/02/14)
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- Synthesis of Quinoline N-Oxides by Cobalt-Catalyzed Annulation of Arylnitrones and Alkynes
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A new and straightforward protocol for the synthesis of quinoline N-oxides from the annulation of arylnitrones and alkynes is described. For the first time, a [4+2] cyclization of nitrone and alkynes has been achieved by cobalt catalysis via a nitrone-assisted dual C–H cleavage under relatively mild conditions. (Figure presented.).
- Liu, Yue,Wang, Chen,Lv, Ningning,Liu, Zhanxiang,Zhang, Yuhong
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supporting information
p. 1351 - 1358
(2017/04/18)
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- Heterogeneous Catalytic Transfer Partial-Hydrogenation with Formic Acid as Hydrogen Source Over the Schiff-Base Modified Gold Nano-Catalyst
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Abstract: The catalytic hydrogenation transformation with gaseous hydrogen in liquid phase always refers to a harsh condition and over-hydrogenation, and it is highly desired to develop new methods with partial-hydrogenation at mild condition. Herein, a heterogeneous catalytic transfer partial-hydrogenation strategy with formic acid as hydrogen source was developed over the Schiff-base modified gold nano-catalysts. The Au/Schiff-SiO2catalyst was successfully prepared by one pot aldimine condensation and NaBH4reduction of a gold precursor. The characterization results indicated that the gold nanoparticles with an average size below 2?nm were highly dispersed over the Schiff-base modified silica support. Such Schiff-based gold nano-catalysts exhibits excellent activity and partial-hydrogenation selectivity, with a high yield (>99%) for phenylacetylene partial-hydrogenation and achieving a 75% chemoselectivity for imines at a relative low temperature and atmospheric pressure. More importantly, the excess of formic acid can be removed by the direct dissociation of formic acid over Au/Schiff-SiO2catalyst with CO2emission into atmosphere, which leads to a hydrogen source as clean as hydrogen gaseous, but with a much more high activity and selectivity under mild reaction process. Graphical Abstract: [Figure not available: see fulltext.]
- Wang, Xinkui,Qiu, Zhen,Liu, Qinggang,Chen, Xiao,Tao, Shengyang,Shi, Chuan,Pang, Min,Liang, Changhai
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p. 517 - 524
(2017/02/18)
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- Direct and Co-catalytic Oxidation of Hydroxylamines to Nitrones Promoted by Rhodium Nanoparticles Supported on Carbon Nanotubes
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Rhodium nanoparticles were assembled on carbon nanotubes, and the resulting nanohybrid was studied in the aerobic oxidation of hydroxylamines to nitrones. Two catalytic systems were developed (i.e., direct or co-catalytic) and both operated to provide high yields of the products, under mild conditions, but with their own specificity as regards the kinetics and regioselectivity of the transformation. In addition, the in situ cycloaddition of the produced nitrones with different alkynes was investigated.
- Prakash, Praveen,Gravel, Edmond,Nguyen, Dinh-Vu,Namboothiri, Irishi N. N.,Doris, Eric
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p. 2091 - 2094
(2017/06/27)
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- Synthesis and Evaluation of Novel 5-cyclohexyl-2-(4″-substitutedphenyl)-3-(2″-substitutedphenyl)4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione Derivatives for Their In Vitro Antioxidant and Antibacterial Activities
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1,3-Dipolar cycloaddition reactions of N-cyclohexyl maleimide (1) with azomethine N-oxide (2) have afforded novel isoxazolidine (3) in excellent yield. Their structures have been characterized from their IR,1H-NMR,13C-NMR,1H,1H-COSY, MS(ESI), and elemental analysis techniques. In vitro antibacterial activity of the synthesized compounds were investigated against a representative panel of pathogenic strains specifically two Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes) and two Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli) using agar-well diffusion assay. Some of the compounds (3a, 3k, 3n, and 3o) exhibited promising antibacterial activities. All the synthesized compounds have also been screened for their antioxidant activities and were found to be significantly active.
- Kaur, Manpreet,Kaur, Anjandeep,Singh, Baldev,Singh, Baljit
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- Chiral: N, N ′-dioxide/Co(II)-promoted asymmetric 1,3-dipolar cycloaddition of nitrones with methyleneindolinones
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A chiral N,N′-dioxide/Co(BF4)2·6H2O complex catalytic system has been developed to efficiently catalyze the asymmetric 1,3-dipolar cycloaddition of nitrones with methyleneindolinones. The corresponding chiral multisubstituted spiroisoxazolidines with three contiguous quaternary-tertiary stereocenters were obtained in moderate to high yields with excellent dr and ee values (up to 97% yield, >19:1 dr and 98% ee).
- Zhang, Dong,Yin, Chengkai,Zhou, Yuhang,Xu, Yali,Lin, Lili,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 7925 - 7928
(2017/07/22)
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- Visible-light-mediated anti-regioselective nitrone 1, 3-dipolar cycloaddition reaction and synthesis of bisindolylmethanes
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The development of photoredox reactions of 1, 3- dipolar cycloaddition of nitrones with alkenes is reported. It offers an efficient synthetic method to obtain isoxazolidine derivatives under mild conditions in synthetically useful yields. The nitrones are cyclized with oxidizable styrenes and aliphatic alkenes via a polar radical crossover cycloaddition reaction through photocatalytic reaction without additives. In addition, bis(indole)methanes can also be prepared through this method.
- Zheng, Lewei,Gao, Fei,Yang, Chao,Gao, Guo-Lin,Zhao, Yating,Gao, Yuan,Xia, Wujiong
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supporting information
p. 5086 - 5089
(2017/11/07)
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- Synthesis of 2,3-Disubstituted NH Indoles via Rhodium(III)-Catalyzed C-H Activation of Arylnitrones and Coupling with Diazo Compounds
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A rhodium-catalyzed intermolecular coupling between arylnitrones and diazo compounds by C-H activation/[4 + 1] annulation with a C(N2)-C(acyl) bond cleavage is reported, and 2,3-disubstituted NH indoles are directly synthesized in up to a 94% yield. A variety of functional groups are applicable to this reaction to give the corresponding products with high selectivity. Compared to other previously reported Rh(III)-catalyzed synthesis of homologous series, this method is simpler, more general, and more efficient.
- Guo, Xin,Han, Jianwei,Liu, Yafeng,Qin, Mingda,Zhang, Xueguo,Chen, Baohua
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p. 11505 - 11511
(2017/11/10)
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- Synthesis of Benzimidazolones via One-Pot Reaction of Hydroxylamines, Aldehydes, and Trimethylsilyl Cyanide Promoted by Diacetoxyiodobenzene
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A novel and efficient PhI(OAc)2-promoted one-pot reaction of aromatic hydroxylamines, aldehydes, and TMSCN in the presence of BF3·Et2O is described. A wide variety of N-substituted benzimidazolones are obtained with satisfactory yields under mild reaction conditions. The method was proven to be efficient for the synthesis of benzimidazolone derivatives from readily available starting materials.
- Zhang, Huaiyuan,Huang, Danfeng,Wang, Ke-Hu,Li, Jun,Su, Yingpeng,Hu, Yulai
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p. 1600 - 1609
(2017/02/10)
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- Nickel(II)-Catalyzed Enantioselective 1,3-Dipolar Cycloaddition of Nitrones with α,β-Unsaturated Acylcarboxylates
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The highly enantioselective 1,3-dipolar cycloaddition of nitrones with α,β-unsaturated acylcarboxylates was realized for the first time by using a chiral bis(indano-oxazoline)-based Ni complex. The reaction proceeded smoothly under mild conditions and provided isoxazolidines with three contiguous stereocenters in high yields with excellent diastereoselectivities (>20:1 dr) and enantioselectivities (up to 99 % ee). The reaction was scaled up to the gram scale, and the products were readily transformed into γ-amino alcohols and other potentially bioactive compounds.
- Xie, Lei,Yu, Xuan,Li, Jiaqi,Zhang, Zhenhua,Qin, Zhaohai,Fu, Bin
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supporting information
p. 657 - 661
(2017/02/05)
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- Cu(II)-catalyzed enantioselective 1,3-dipolar cycloaddition of nitrones with α, β-unsaturated acyl phosphonates
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A highly enantioselective 1, 3-dipolar cycloaddition of nitrone with α, β-unsaturated acyl phosphonate was developed for the first time by using a chiral indane-bis(oxazoline)-copper(II) complex. The reaction proceeded smoothly under mild conditions to provide isoxazolidines with multi-stereocenters in good yields with high to excellent diastereo- (>20:1 dr) and enantioselectivities (up to 99% ee). The resulting products were readily converted to multi-functional isoxazolidines or γ-amino alcohol compounds.
- Xie, Lei,Bai, Hui,Li, Jiaqi,Yu, Xuan,Zhang, Zhenhua,Fu, Bin
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supporting information
p. 2923 - 2930
(2017/04/27)
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- High diastereoselectivity induced by intermolecular hydrogen bonding in [3?+?2] cycloaddition reaction: experimental and computational mechanistic approaches
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A diastereoselective [3?+?2] cycloaddition of N-aryl substituted maleimides with N,α-diphenyl nitrone possessing 11-hydroxyundecyloxy as a flexible substituent was performed. Experimental and comprehensive mechanistic density functional theory studies reveals that intermolecular H-bonding and steric repulsive interaction predominate exo-Z and exo-E cycloaddition transition states, respectively. The reaction proceeded smoothly depending on the reactants and gave a good yield of (syn) cis-isoxazolidine or (anti) trans-isoxazolidine as a single diastereomer.
- Y?ld?r?m, Ayhan,Kaya, Yunus
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- REGULATORS FOR CONTROLLING LINEAR AND PSEUDO-RING EXPANSION POLYMERIZATION OF VINYL MONOMERS
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The invention concerns new regulator compounds for a novel polymerization process for vinyl monomers, which yields polymers with improved control over composition and nearly full to full conservation of architectural integrity up to high conversion. The regulator compounds are defined by according to anyone of the Formulas (1A), (1B), (1C), (1D), (1E), (1F), (1G), (1H) and (1I), wherein R1 stands for an optionally substituted secondary or tertiary alkyl or secondary or tertiary aralkyl; Z1 stands for -CN or a carboxylic acid ester of formula C(O)OR21; Z2 may be chosen from the group of -CN, carboxylic acid, salts of carboxylic acids, carboxylic acid ester, carboxylic acid amides, (hetero)aryl, alkenyl and halogen; R2, R3, R4 and R5 are each independently chosen from the group of H, alkyl, aralkyl, (hetero)aryl, -CN and carboxylic acid ester of formula C(O)OR22; R7 stands for a primary alkyl or primary aralkyl, -CN or hydrogen; Y stands for a bridging group and n is 2, 3, 4, 5 or 6; in case R1 stands for tertiary alkyl or tertiary aralkyl, R6 stands for a primary alkyl or primary aralkyl, -CN or a carboxylic acid ester of formula C(O)OR26; in case R1 stands for a secondary alkyl or secondary aralkyl, R6 stands for a primary or secondary alkyl or primary or secondary aralkyl, -CN, a carboxylic acid ester of formula C(O)OR26 or a phosphonic acid ester of formula P(O)(OR27)2, a (hetero)aryl or an alkenyl; R21, R22, R26 and R27 each independently stand for alkyl or aralkyi having from 1-30 carbon atoms, optionally containing heteroatoms.
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Page/Page column 30; 35; 36
(2017/07/01)
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- α-Aryl-N-aryl nitrones: Synthesis and screening of a new scaffold for cellular protection against an oxidative toxic stimulus
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Nitrone-containing compounds are commonly employed as spin traps of free radical species in chemical and biological studies. Some molecules as α-phenyl-N-t-butyl nitrone (PBN) and its derivatives have been tested as potential drugs to treat oxidative stress related diseases, as Alzheimer and stroke for example. In this work we report the design and the synthesis of α-aryl-N-aryl nitrones and their cytoprotection profile on human neuroblastoma cells (SH-SY5Y) under induced oxidative stress. All the nine synthesized nitrones showed a significant response at low micromolar concentration. The selected compound 8 (α-phenyl-N-phenyl nitrone) increased the reduced glutathione (GSH) levels by 65% and lowered the necrotic cell death from 25.8% to 3.8%. Based on our data, the designed highly conjugated nitrone double-bond skeleton can be considered as a good scaffold for further studies regarding oxidative stress-related diseases.
- Matias,Biazolla,Cerchiaro,Keppler
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p. 232 - 239
(2015/12/31)
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- Visible light active CdS nanorods: One-pot synthesis of aldonitrones
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This is the first report on nano semiconductor photocatalytic synthesis of aldonitrones through in situ trapping of hydroxylamine intermediates in the presence of aromatic aldehydes in aqueous media under visible light irradiation. A new highly efficient dispersible CdS nanorod photocatalyst was synthesized. The characterization of the catalyst was done by transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, CHNS elemental analysis, thermogravimetric analysis (TGA) and diffuse reflection spectroscopy (DRS). The CdS nanorods have 12-18 nm sizes according to TEM. The catalyst was used successfully in the chemoselective photocatalytic reduction of nitroarenes using a CdS/poly ethyleneglycol 400-water system (CdS/PEG-H2O). The reaction was successfully carried out under green and blue LED illumination by using ammonium formate as a sacrificial electron donor in the presence and absence of an aldehyde, producing aromatic amines or aromatic nitrones respectively. The reusability of the CdS nanorod photocatalyst was tested four times. Moreover, the stability of the catalyst was confirmed by the characterization of a reused catalyst.
- Ramdar, Moosa,Kazemi, Foad,Kaboudin, Babak,Taran, Zahra,Partovi, Adel
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p. 9257 - 9262
(2016/11/09)
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- Triphenylbismuth carbonate-mediated oxidation of hydroxylamines to nitrones and: In situ 1,3-dipolar cycloaddition
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Triphenylbismuth carbonate was shown to act as a mild, selective and efficient reagent for the oxidation of hydroxylamines. The developed reaction conditions were shown to be compatible with the in situ trapping of the produced nitrones by a strained alkyne, via a [3 + 2] cycloaddition reaction.
- Nguyen, Dinh-Vu,Prakash, Praveen,Gravel, Edmond,Doris, Eric
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p. 89238 - 89241
(2016/10/03)
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- Stereoselective Synthesis of Ezetimibe via Cross-Metathesis of Homoallylalcohols and α-Methylidene-β-Lactams
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Ru-catalyzed cross-metathesis (CM) reaction between β-arylated α-methylidene-β-lactams and terminal olefins was developed. The CM reaction is effectively catalyzed with Hoveyda-Grubbs second-generation catalyst affording corresponding α-alkylidene-β-aryl-
- Humpl, Marek,Tauchman, Ji?í,Topolov?an, Nikola,Kretschmer, Jan,Hessler, Filip,Císa?ová, Ivana,Kotora, Martin,Vesely, Jan
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p. 7692 - 7699
(2016/09/09)
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- Influence of the side-group at C=N bridging bond of bis-aryl Schiff bases on the wavelength of absorption maximum of ultraviolet absorption spectra
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The compounds N-(benzylidene)-anilines XArCH=NArY (XBAY), N-(phenyl-ethylene)-anilines XArC(CH3)=NArY (XPEAY) and N-phenyl-α-phenylnitrones XArCH=N(O)ArY (XPNY) have bridging group CH=N, C(CH3)=N and CH=N(O) respectively, in which the C(CH3)=N has a side-group methyl CH3 at carbon end and the CH=N(O) has a side-group O atom at nitrogen end. In this work, a series of XPEAY and XPNY were synthesized, and their longest wavelength maximum λmax (nm) of ultraviolet absorption spectra were measured. Then the change regularity of the νmax (cm-1, νmax=1/λmax) of XPEAY and XPNY were investigated, and they were compared with that of XBAY (reported by ref.26). The results indicate: (1) There are no good linear relationships between the νmax of XBAYs and XPEAYs or XPNYs. (2) In case of a same set of X-Y group couples, the distribution of λmax of XPEAYs is larger than that of XPNYs. (3) The side-group CH3 makes the effect of σ(X) larger than that of σ(Y) on the νmax of XPEAYs, whereas the O atom makes the effect of σ(Y) larger than that of σ(X) on the νmax of XPNYs. (4) The cross-interaction between X and Y has important effect on the all νmax. However, the cross-interaction between CH3 and X/Y has not important effect on the νmax of XPEAY, and the cross-interaction between O and X/Y has not important effect on the νmax of XPNY. Copyright
- Luo, Qingqing,Cao, Chao-Tun,Cao, Zhongzhong,Cao, Chenzhong
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p. 406 - 413
(2016/07/28)
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- Iron-Catalyzed Cyclization of Nitrones with Geminal-Substituted Vinyl Acetates: A Direct [4 + 2] Assembly Strategy Leading to 2,4-Disubstituted Quinolines
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An iron-catalyzed intermolecular [4 + 2] cyclization of arylnitrones with geminal-substituted vinyl acetates was developed for the synthesis of 2,4-disubstituted quinolines in moderate to good yields with good functional group compatibilities. Preliminary mechanistic studies suggest a plausible iron-catalyzed C-H activation process under external-oxidant-free conditions.
- Zhong, Mingbing,Sun, Song,Cheng, Jiang,Shao, Ying
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p. 10825 - 10831
(2016/11/29)
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