- Reactivity of substrates with multiple competitive reactive sites toward NBS under neat reaction conditions promoted by visible light
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Regioselectivity of visible-light-induced transformations of a range of (hetero)aryl alkyl-substituted ketones bearing several competitive reactive sites (α-carbonyl, benzyl and aromatic ring) with N-bromosuccinimide (NBS) was studied under solvent-free reaction conditions (SFRC) and in the absence of inert-gas atmosphere, radical initiators and catalysts. An 8-W energy-saving household lamp was used for irradiation. Heterogeneous reaction conditions were dealt with throughout the study. All substrates were mono- or dibrominated at the α-carbonyl position, and additionally, some benzylic or aromatic bromination was observed in substrates with benzylic carbon atoms or electron-donating methoxy groups, respectively. Surprisingly, ipso-substitution of the acyl group with a bromine atom took place with (4-methoxynaphthyl) alkyl ketones. While the addition of the radical scavenger TEMPO (2,2,6,6-tetramethylpiperidin-1-yloxy) decreased the extent of α- and ring bromination, it completely suppressed the benzylic bromination and α,α-dibromination with NBS under SFRC.
- Grjol, Bla?,Jereb, Marjan
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p. 5235 - 5248
(2021/06/07)
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- Regioselective Oxybromination of Benzene and Its Derivatives by Bromide Anion with a Mononuclear Nonheme Mn(IV)-Oxo Complex
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Oxybromination of aromatic compounds by high-valent metal-oxo intermediates has yet to be explored despite extensive studies on the oxybromination of aliphatic C-H bonds of hydrocarbons. Herein, we report the regioselective oxybromination of methoxy-substituted benzenes by a nonheme MnIV-oxo complex binding scandium ions, [(Bn-TPEN)MnIV(O)]2+-(Sc(OTf)3)2 (1), in the presence of tetrabutylammonium bromide. The regioselective oxybromination occurs at the carbon atom with the highest positive charge via electron transfer (ET) from the methoxy-substituted benzenes to 1. ET driving force dependence of the rate constants of ET from methoxy-substituted benzenes to 1 is well fitted in light of the Marcus theory of ET. Under photoirradiation, the oxybromination of benzene by 1 can be achieved via ET from benzene to the photoexcited state of 1, although no reaction occurs between benzene and the ground state of 1 in the dark. To the best of our knowledge, this is the first example of reporting the stoichiometric regioselective oxybromination of the benzene ring by a synthetic high-valent Mn(IV)-oxo complex and the catalytic regioselective oxybromination reaction with a Mn(II) complex and a terminal oxidant.
- Sharma, Namita,Lee, Yong-Min,Li, Xiao-Xi,Nam, Wonwoo,Fukuzumi, Shunichi
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supporting information
p. 14299 - 14303
(2019/11/03)
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- Two Stereoinduction Events in One C?H Activation Step: A Route towards Terphenyl Ligands with Two Atropisomeric Axes
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Herein we disclose the synthesis of original chiral scaffolds—ortho-orientated terphenyls presenting two atropisomeric Ar–Ar axes. These unusual structures were built up by using the C?H activation approach, and remarkably, both chiral axes were controlled with excellent stereoselectivity in a single transformation. During the reaction, not only does atroposelective functionalization of a biaryl precursor occur to establish one stereogenic axis, but an unprecedented atropo-stereoselective C?H arylation also takes place to generate the second stereogenic element. These enantiomerically pure ortho-terphenyls show an original tridimensional structure and thus constitute a unique foundation for building up a library of enantiomerically pure bidentate ligands, such as the new ligands S/N-Biax and diphosphine BiaxPhos.
- Dherbassy, Quentin,Djukic, Jean-Pierre,Wencel-Delord, Joanna,Colobert, Fran?oise
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supporting information
p. 4668 - 4672
(2018/03/21)
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- Photocatalytic Selective Bromination of Electron-Rich Aromatic Compounds Using Microporous Organic Polymers with Visible Light
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Pure organic, heterogeneous, metal-free, and visible light-active photocatalysts offer a more sustainable and environmentally friendly alternative to traditional metal-based catalysts. Here we report a series of microporous organic polymers containing photoactive conjugated organic semiconductor units as heterogeneous photocatalysts for a visible-light-promoted, highly selective bromination reaction of electron-rich aromatic compounds using HBr as a bromine source and molecular oxygen as a clean oxidant. Via a simple Friedel-Crafts alkylation reaction, the microporous organic polymers were obtained by cross-linking of organic semiconductor compounds with defined valence and conduction band positions. The utilization of the simply prepared porous polymer-based photocatalytic systems opens new opportunities toward a sustainable and efficient material design for catalysis.
- Li, Run,Wang, Zi Jun,Wang, Lei,Ma, Beatriz Chiyin,Ghasimi, Saman,Lu, Hao,Landfester, Katharina,Zhang, Kai. A. I.
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p. 1113 - 1121
(2016/02/18)
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- Efficient and Practical Oxidative Bromination and Iodination of Arenes and Heteroarenes with DMSO and Hydrogen Halide: A Mild Protocol for Late-Stage Functionalization
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An efficient and practical system for inexpensive bromination and iodination of arenes as well as heteroarenes by using readily available dimethyl sulfoxide (DMSO) and HX (X = Br, I) reagents is reported. This mild oxidative system demonstrates a versatile protocol for the synthesis of aryl halides. HX (X = Br, I) are employed as halogenating reagents when combined with DMSO which participates in the present chemistry as a mild and inexpensive oxidant. This oxidative system is amenable to late-stage bromination of natural products. The kilogram-scale experiment (>95% yield) shows great potential for industrial application.
- Song, Song,Sun, Xiang,Li, Xinwei,Yuan, Yizhi,Jiao, Ning
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supporting information
p. 2886 - 2889
(2015/06/30)
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- PROCESS FOR PRODUCTION OF OXIDATION REACTION PRODUCT OF AROMATIC COMPOUND
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The present invention provides a process for producing an oxidation reaction product of an aromatic compound, having excellent environmental load reduction performance, cost reduction performance, etc. Provided is a process for producing an oxidation reaction product of a raw material aromatic compound by reacting the raw material aromatic compound with an oxidizing agent. The process further uses an electron donor-acceptor linked molecule. The process includes the step of: reacting the electron donor-acceptor linked molecule in an electron-transfer state, the oxidizing agent, and the raw material aromatic compound, thereby generating an oxidation reaction product resulting from oxidation of the raw material aromatic compound.
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Page/Page column 18
(2012/07/14)
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- Improved arene fluorination methodology for I(III) salts
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(Equation Presented). The use of low polarity aromatic solvents (benzene or toluene) and/or the removal of inorganic salts results in dramatically improved yields of fluorinated arenes from diaryliodonium salts. This methodology is shown to "scale down" to the conditions used typically for radiotracer synthesis.
- Wang, Bijia,Qin, Linlin,Neumann, Kiel D.,Uppaluri, Shriharsha,Cerny, Ronald L.,DiMagno, Stephen G.
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supporting information; experimental part
p. 3352 - 3355
(2010/11/02)
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- NOVEL INHIBITORS OF BETA-LACTAMASE
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This invention provides novel β-lactamase inhibitors of the aryl- and heteroarylsulfonamidomethylphosphonate monoester class having nitrogen-based cations or quarternary ammonium groups. The compounds inhibit three classes of β-lactamases and synergize the antibacterial effects of β-lactam antibiotics (e.g., imipenem and ceftazidime) against those micro-organisms normally resistant to the β-lactam antibiotics as a result of the presence of the β-lactamases. Formula (I) or pharmaceutically acceptable salt thereof.
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Page/Page column 18
(2010/12/29)
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- Oxidative bromination of aromatic compounds using O-iodoxybenzoic acid with tetraethylammonium bromide
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A mild and selective procedure for the bromination of activated arenes using o-iodoxybenzoic acid and tetraethylammonium bromide is presented. The reactions were carried out at room temperature and gave moderate to excellent yields. Copyright Taylor & Francis Group, LLC.
- Bhalerao, Dinesh S.,Mahajan, Ulhas S.,Akamanchi, Krishnacharya G.
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experimental part
p. 2814 - 2819
(2009/04/04)
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- Synthesis of both enantiomers of protoberberines via laterally lithiated (S)-4-isopropyl-2-(o-tolyl)-oxazolines
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The addition of the laterally lithiated (S)-4-isopropyl-2-(o- tolyl)oxazoline (1) to 6,7-dimethoxy-3,4-dihydroisoquinoline (2) proceeded in modest diastereoselectivity. However, the addition products (3a) and (3b) were easily separated by column chromatography over silica gel. Acid-catalyzed lactamization of 3a and 3b followed by LiAlH4-reduction afforded the corresponding optically pure protoberberines (8a) and (8b), respectively. This procedure was successfully applied to the synthesis of both enantiomers of xylopinine and bharatamine.
- Fukuda, Tsutomu,Iwao, Masatomo
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p. 701 - 720
(2008/09/18)
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- NOVEL SULFONAMIDOMETHYLPHOSPHONATE INHIBITORS OF BETA-LACTAMASE
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This invention provides novel β-lactamase inhibitors of the aryl-and heteroaryl-sulfonamidomethylphosphonate monoester class. The compounds inhibit three classes of β-lactamases and synergize the antibacterial effects of β-lactam antibiotics (e.g., imipenem and ceftazimdime) against those micro-organisms normally resistant to the β-lactam antibiotics as a result of the presence of the β-lactamases. Formula (I) or a pro-drug or pharmaceutically acceptable salt thereof, wherein: W represents: Formula (II).
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Page/Page column 24
(2008/06/13)
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- Asymmetric synthesis of the protoberberine alkaloid (s)-(-)-xylopinine using enantiopure sulfinimines
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A concise enantioselective synthesis of (S)-(-)-xylopinine (1) is described involving the addition of the laterally lithiated derivative of o-tolunitrile of 16 to enantiopure sulfinimine (+)-14. Treatment of the resulting cyano sulfinamide adduct (-)-17b with DIBAL-H accomplishes five operations in a single pot and furnishes the cyclic imine (+)-18 in good yield. Reduction and cyclization affords (S)-(-)-1. Alternatively basic hydrolysis of 17b,c gives isoquinolone 21 that is cyclized and reduced to give (S)-(-)-1.
- Davis, Franklin A.,Mohanty, Pradyumna K.
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p. 1290 - 1296
(2007/10/03)
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- Multisubstituted 1-hydroxy-9-acridones with anticancer activity
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The present invention provides a compound having the structure: STR1 The present invention also provides a method for synthesizing a compound having the above-identified structure as well as the intermediate compounds produced according to that method. The present invention further provides a pharmaceutical composition comprising the above compounds. Lastly, the present invention provides a method of inhibiting growth of tumor cells.
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- SUBSTITUENT EFFECTS ON THE PHOTOCHEMISTRY OF o-TOLUALDEHYDES
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The effect of 4-oxy and 4,5-dioxy substituents on the photochemical conversion of 2-methylbenzaldehydes to o-quinodimethanes (o-QDMs) has been studied.The presence of a 4-methoxy, or a 4 and 5-methoxy substituent prevented the photochemical formation of the o-QDM whereas 4-acetoxy and 4,5-diacetoxy-2-methylbenzaldehyde and the corresponding mesylates and tosylates were successfully converted to the o-QDMs.
- Charlton, James L.,Koh, Kevin
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p. 5595 - 5598
(2007/10/02)
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