- Decatungstate-mediated solar photooxidative cleavage of CC bonds using air as an oxidant in water
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With the increasing attention for green chemistry and sustainable development, there has been much interest in searching for greener methods and sources in organic synthesis. However, toxic additives or solvents are inevitably involved in most organic transformations. Herein, we first report the combination of direct utilization of solar energy, air as the oxidant and water as the solvent for the selective cleavage of CC double bonds in aryl olefins. Various α-methyl styrenes, diaryl alkenes as well as terminal styrenes are well tolerated in this green and sustainable strategy and furnished the desired carbonyl products in satisfactory yields. Like heterogeneous catalysis, this homogeneous catalytic system could also be reused and it retains good activity even after repeating three times. Mechanism investigations indicated that both O2- and 1O2 were involved in the reaction. Based on these results, two possible mechanisms, including the electron transfer pathway and the energy transfer pathway, were proposed.
- Du, Dongdong,Luo, Junfei,Shi, Sanshan,Xie, Pan,Xue, Cheng
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p. 5936 - 5943
(2021/08/23)
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- Radical C?H Trifluoromethoxylation of (Hetero)arenes with Bis(trifluoromethyl)peroxide
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Trifluoromethoxylated (hetero)arenes are of great interest for several disciplines, especially in agro- and medicinal chemistry. Radical C?H trifluoromethoxylation of (hetero)arenes represents an attractive approach to prepare such compounds, but the high cost and low atom economy of existing .OCF3 radical sources make them unsuitable for the large-scale synthesis of trifluoromethoxylated building blocks. Herein, we introduce bis(trifluoromethyl)peroxide (BTMP, CF3OOCF3) as a practical and efficient trifluoromethoxylating reagent that is easily accessible from inexpensive bulk chemicals. Using either visible light photoredox or TEMPO catalysis, trifluoromethoxylated arenes could be prepared in good yields under mild conditions directly from unactivated aromatics. Moreover, TEMPO catalysis allowed for the one-step synthesis of valuable pyridine derivatives, which have been previously prepared via multi-step approaches.
- Dix, Stefan,Golz, Paul,Schmid, Jonas R.,Riedel, Sebastian,Hopkinson, Matthew N.
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supporting information
p. 11554 - 11558
(2021/07/09)
-
- Green Synthesis of Leaning Tower[6]arene-Mediated Gold Nanoparticles for Label-Free Detection
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Here a facile synthesis strategy toward carboxylated leaning tower[6]arene (CLT6)-mediated gold nanoparticles (CLT6-AuNPs) without external energy sources and reducing agents has been developed. Due to the cavity structure of CLT6, CLT6-AuNPs with a controllable particle size show good stability and excellent performance in label-free detection of diquat. Significantly, we reveal the reduction mechanism of AuNP formation, which is the cleavage of some phenyl ether bonds of CLT6 to produce reductive phenols, thus reducing Au3+ to AuNPs.
- Zhang, Hao,Wang, Xin,Huang, Kun-Tao,Liang, Feng,Yang, Ying-Wei
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supporting information
p. 4677 - 4682
(2021/06/28)
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- Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity
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The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C10H6R2N2CH2CH2]2+ (R=H [1 a]2+, Me [1 f]2+, tBu [1 g]2+), and [C12H4R4N2CH2CH2]2+ (R=H [2 a]2+, Me [2 b]2+) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]2+ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp3(C?F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF3)3C6H9. The dications are shown to act as hydride acceptors with the isolation of neutral species C16H14N2 (3 a) and C16H10Me4N2 (3 b) and monocationic species [C14H13N2]+ ([4 a]+) and [C18H21N2]+ ([4 b]+). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.
- Burton, Katherine I.,Elser, Iris,Waked, Alexander E.,Wagener, Tobias,Andrews, Ryan J.,Glorius, Frank,Stephan, Douglas W.
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supporting information
p. 11730 - 11737
(2021/07/16)
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- Covalent Organic Frameworks Enabling Site Isolation of Viologen-Derived Electron-Transfer Mediators for Stable Photocatalytic Hydrogen Evolution
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Electron transfer is the rate-limiting step in photocatalytic water splitting. Viologen and its derivatives are able to act as electron-transfer mediators (ETMs) to facilitate the rapid electron transfer from photosensitizers to active sites. Nevertheless, the electron-transfer ability often suffers from the formation of a stable dipole structure through the coupling between cationic-radical-containing viologen-derived ETMs, by which the electron-transfer process becomes restricted. Herein, cyclic diquats, a kind of viologen-derived ETM, are integrated into a 2,2′-bipyridine-based covalent organic framework (COF) through a post-quaternization reaction. The content and distribution of embedded diquat-ETMs are elaborately controlled, leading to the favorable site-isolated arrangement. The resulting materials integrate the photosensitizing units and ETMs into one system, exhibiting the enhanced hydrogen evolution rate (34600 μmol h?1 g?1) and sustained performances when compared to a single-module COF and a COF/ETM mixture. The integration strategy applied in a 2D COF platform promotes the consecutive electron transfer in photochemical processes through the multi-component cooperation.
- Mi, Zhen,Zhou, Ting,Weng, Weijun,Unruangsri, Junjuda,Hu, Ke,Yang, Wuli,Wang, Changchun,Zhang, Kai A. I.,Guo, Jia
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supporting information
p. 9642 - 9649
(2021/03/16)
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- Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow
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The first example of photocatalytic trifluoromethoxylation of arenes and heteroarenes under continuous-flow conditions is described. Application of continuous-flow microreactor technology allowed to reduce the residence time up to 16 times in comparison t
- Cendón, Borja,Gulías, Moisés,Ho, Michelle,No?l, Timothy,Nyuchev, Alexander V.,Sambiagio, Carlo,Struijs, Job J. C.,Wan, Ting,Wang, Ying
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supporting information
p. 1305 - 1312
(2020/07/10)
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- Redox-Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C?H Di- and Trifluoromethoxylation
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Applications of TEMPO. catalysis for the development of redox-neutral transformations are rare. Reported here is the first TEMPO.-catalyzed, redox-neutral C?H di- and trifluoromethoxylation of (hetero)arenes. The reaction exhibits a broad substrate scope, has high functional-group tolerance, and can be employed for the late-stage functionalization of complex druglike molecules. Kinetic measurements, isolation and resubjection of catalytic intermediates, UV/Vis studies, and DFT calculations support the proposed oxidative TEMPO./TEMPO+ redox catalytic cycle. Mechanistic studies also suggest that Li2CO3 plays an important role in preventing catalyst deactivation. These findings will provide new insights into the design and development of novel reactions through redox-neutral TEMPO. catalysis.
- Lee, Johnny W.,Lim, Sanghyun,Maienshein, Daniel N.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 21475 - 21480
(2020/10/02)
-
- Identification of new aryl hydrocarbon receptor (AhR) antagonists using a zebrafish model
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A new series of 1,3-diketone, heterocyclic and α,β-unsaturated derivatives were synthesized and evaluated for their AhR antagonist activity using zebrafish and mammalian cells. Compounds 1b, 2c, 3b and 5b showed significant AhR antagonist activity in a transgenic zebrafish model. Among them, compound 3b, and 5b were found to have excellent AhR antagonist activity with IC50 of 3.36 nM and 8.3 nM in a luciferase reporter gene assay. In stem cell proliferation assay, compound 5b elicited marked HSC expansion.
- Jeong, Jieun,Kim, Kun-Hee,Kim, Dong-Young,Chandrasekaran, Gopalakrishnan,Kim, Minhee,Pagire, Suvarna H.,Dighe, Mahesh,Choi, Eun Young,Bak, Su-Min,Kim, Eun-Young,Shin, Myung-Geun,Choi, Seok-Yong,Ahn, Jin Hee
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- Visible-Light Photoredox-Catalyzed and Copper-Promoted Trifluoromethoxylation of Arenediazonium Tetrafluoroborates
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We report the development of photoredox-catalyzed and copper-promoted trifluoromethoxylation of arenediazonium tetrafluoroborates, with trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxylation reagent. This new method takes advantage of visible-light photoredox catalysis to generate the aryl radical under mild conditions, combined with copper-promoted selective trifluoromethoxylation. The reaction is scalable, tolerates a wide range of functional groups, and proceeds regioselectively under mild reaction conditions. Furthermore, mechanistic studies suggested that a Cs[Cu(OCF3)2] intermediate might be generated during the reaction.
- Yang, Shaoqiang,Chen, Miao,Tang, Pingping
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supporting information
p. 7840 - 7844
(2019/05/15)
-
- Synthesis method of primary amine hydrochloride
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The invention discloses a synthesis method of primary amine hydrochloride. According to the synthesis method, in the presence of a gold complex, water and alkyne carry out catalytic hydrolysis to generate ketones, and then ketones and ammonium formate are catalyzed by a rhodium complex to generate primary amine. Compared with a conventional primary amine synthesis method, the synthesis method hasthe advantages that no alkali is added during the reaction process, no side product is generated, the atomic economy is good, the reaction conditions are mild, and the synthesis method has a wide prospect.
- -
-
Paragraph 0069-0072
(2019/03/09)
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- Efficient Palladium(0) supported on reduced graphene oxide for selective oxidation of olefins using graphene oxide as a ‘solid weak acid’
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Selective oxidation of olefin derivatives to ketones has made innovative development over palladium(0) supported on reduced graphene oxide. Compared to traditional Wacker oxidation, the novel method offers an economical and environment-friendly option by using graphene oxide (GO) as a ‘solid weak acid’ instead of classical homogeneous catalysts like H2SO4 and CF3COOH. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscopy images of Pd0/RGO showed that the nanoscaled Pd particles generated at the flake structure of reduced graphene oxide. Under optimized condition, up to 44 kinds of ketones with different structures can be prepared with excellent yields.
- Gao, Xi,Zhou, Jianhao,Peng, Xinhua
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-
- DIFLUOROMETHOXYLATION AND TRIFLUOROMETHOXYLATION COMPOSITIONS AND METHODS FOR SYNTHESIZING SAME
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The present invention provides a compound having the structure (I), a processing of making the compound; and a process of using the compound as a reagent for the difluoromethoxylation and trifluoromethoxylation of arenes or heteroarenes.
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Page/Page column 75; 79; 118-119; 124
(2019/09/18)
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- Stable Radical Cation-Containing Covalent Organic Frameworks Exhibiting Remarkable Structure-Enhanced Photothermal Conversion
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The production of a radical cation-containing covalent organic framework (COF) has been accomplished by sequential in situ reactions, quaternization, and one-electron reduction of the 2,2′-bipyridine-based COFs. The acid-catalyzed COF formation enables the cis configuration of 2,2′-bipyridyl moieties in the structure, of which the stability arises from the eclipsed stacking of the two-dimensional layered structure. The postfunctionalization generates cyclic alkylated diquats as the sole products from the controlled quaternization. The reduction of diquat cations on the COF skeletons results in a large number of radical cations, which delocalize and uniaxially stack on top of one another by virtue of interlayered ?-electronic couplings. The absorption of the near-infrared (NIR) region exhibited by the cationic radical COF is remarkably high owing to the intercharge transfer across the ?-coupling interlayers. Also, the long-range array of extended and planar frameworks in such a COF leads to the extra stability of the radical cations against external stresses. The structure-enhanced performance of the COF material is witnessed with photothermal conversion efficiencies of as high as 63.8 and 55.2% when exposed to 808 and 1064 nm lasers, respectively. Further PEG modification on such a COF allows photoacoustic imaging and photothermal therapy in vivo under NIR light illumination to be manifested.
- Mi, Zhen,Yang, Peng,Wang, Rong,Unruangsri, Junjuda,Yang, Wuli,Wang, Changchun,Guo, Jia
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supporting information
p. 14433 - 14442
(2019/10/11)
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- Tetrachlorocuprate-bipyridyl quaternary ammonium salt and preparation method and application thereof
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The invention belongs to the technical field of fine chemosynthesis and particularly relates to a tetrachlorocuprate-bipyridyl quaternary ammonium salt with weeding and antibacterial dual functions. Acompound prepared from tetrachlorocuprate anions and 1,1'-ethylene-2,2'-bipyridyl cations has a chemical structure represented by a formula (I), i.e., shortened for [EtBiPy][CuCl4]. A preparation method of the compound comprises the steps of preparing a 1,1'-ethylene-2,2'-bipyridyl dibromo salt, preparing the tetrachlorocuprate anions and preparing the tetrachlorocuprate-bipyridyl quaternary ammonium salt. The tetrachlorocuprate-bipyridyl quaternary ammonium salt provided by the invention has relatively high antibacterial capability to Staphylococcus aureus and Escherichia coli and also has arelatively good contact poisoning effect on weeds.
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-
Paragraph 0013; 0022-0025
(2019/02/03)
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- Redox-Active Reagents for Photocatalytic Generation of the OCF3 Radical and (Hetero)Aryl C?H Trifluoromethoxylation
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The trifluoromethoxy (OCF3) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF3 radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported. More importantly, the reagent allows catalytic, intermolecular C?H trifluoromethoxylation of a broad array of (hetero)arenes and biorelevant compounds. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1 resulting in exclusive liberation of the OCF3 radical. Addition of this radical to (hetero)arenes gives trifluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of trifluoromethoxylation.
- Zheng, Weijia,Lee, Johnny W.,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 13795 - 13799
(2018/09/27)
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- Radical Trifluoromethoxylation of Arenes Triggered by a Visible-Light-Mediated N?O Bond Redox Fragmentation
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A simple trifluoromethoxylation method enables non-directed functionalization of C?H bonds on a range of substrates, providing access to aryl trifluoromethyl ethers. This light-driven process is distinctly different from conventional procedures and occurs through an OCF3 radical mechanism mediated by a photoredox catalyst, which triggers an N?O bond fragmentation. The pyridinium-based trifluoromethoxylation reagent is bench-stable and provides access to synthetic diversity in lead compounds in an operationally simple manner.
- Jelier, Benson J.,Tripet, Pascal F.,Pietrasiak, Ewa,Franzoni, Ivan,Jeschke, Gunnar,Togni, Antonio
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supporting information
p. 13784 - 13789
(2018/09/14)
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- Catalytic C?H Trifluoromethoxylation of Arenes and Heteroarenes
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The intermolecular C?H trifluoromethoxylation of arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox-active catalysts for the direct (hetero)aryl C?H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy-to-handle reagents, requires only 0.03 mol % of redox-active catalysts, does not need specialized reaction apparatus, and tolerates a wide variety of functional groups and complex structures such as sugars and natural product derivatives. Importantly, both ground-state and photoexcited redox-active catalysts are effective. Detailed computational and experimental studies suggest a unique reaction pathway where photoexcitation of the trifluoromethoxylating reagent releases the OCF3 radical that is trapped by (hetero)arenes. The resulting cyclohexadienyl radicals are oxidized by redox-active catalysts and deprotonated to form the desired products of trifluoromethoxylation.
- Zheng, Weijia,Morales-Rivera, Cristian A.,Lee, Johnny W.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 9645 - 9649
(2018/03/21)
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- O-Trifluoromethylation of Phenols: Access to Aryl Trifluoromethyl Ethers by O-Carboxydifluoromethylation and Decarboxylative Fluorination
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A new strategy for the synthesis of aryl trifluoromethyl ethers (ArOCF3) by combining O-carboxydifluoromethylation of phenols and subsequent decarboxylative fluorination is reported. This protocol allows easy construction of functionalized trifluoromethoxybenzenes and trifluoromethylthiolated arenes (ArSCF3) in moderate to good yields. Moreover, it utilizes accessible and inexpensive reagents sodium bromodifluoroacetate and SelectFluor II and, thus, is practical for O-trifluoromethylation of phenols. The potential application of this method is demonstrated with the preparation of a plant-growth regulator, Flurprimidol.
- Zhou, Min,Ni, Chuanfa,He, Zhengbiao,Hu, Jinbo
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supporting information
p. 3754 - 3757
(2016/08/16)
-
- Design, synthesis and pharmacology of 1,1-bistrifluoromethylcarbinol derivatives as liver X receptor β-selective agonists
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A novel series of 1,3-bistrifluoromethylcarbinol derivatives that act as liver X receptor (LXR) β-selective agonists was discovered. Structure-activity relationship studies led to the identification of molecule 62, which was more effective (Emax) and selective toward LXRβ than T0901317 and GW3965. Furthermore, 62 decreased LDL-C without elevating the plasma TG level and significantly suppressed the lipid-accumulation area in the aortic arch in a Bio F1B hamster fed a diet high in fat and cholesterol. We demonstrated that our LXRβ agonist would be potentially useful as a hypolipidemic and anti-atherosclerotic agent. In this manuscript, we report the design, synthesis and pharmacology of 1,3-bistrifluoromethylcarbinol derivatives.
- Koura, Minoru,Matsuda, Takayuki,Okuda, Ayumu,Watanabe, Yuichiro,Yamaguchi, Yuki,Kurobuchi, Sayaka,Matsumoto, Yuuki,Shibuya, Kimiyuki
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p. 2668 - 2674
(2015/06/08)
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- Small Crystal ZSM-5, Its Synthesis and Use
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A molecular sieve having the framework structure of ZSM-5 is described comprising crystals having an external surface area in excess of 100 m2/g (as determined by the t-plot method for nitrogen physisorption) and a unique X-ray diffraction pattern.
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- Effect of chemical structure of bipyridinium salts as electron carrier on the visible-light induced conversion of CO2 to formic acid with the system consisting of water-soluble zinc porphyrin and formate dehydrogenase
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Effect of chemical structures of some 2,2′-bipyridinium salts (BP2+) as the electron carrier molecules on the visible-light induced conversion of CO2 to formic acid with the system consisting of water-soluble zinc tetraphneylporphyrin tetrasulfonate (ZnTPPS) and formate dehydrogenase (FDH) in the presence of triethanolamine (TEOA) as an electron donor molecule was investigated. Irradiation of a CO2 saturated solution containing TEOA, ZnTPPS, BP2+ and FDH with visible light resulted in production of formic acid. By using 1,1′-ethylene-2,2′-bipyridinium dibromide (DB2+) as an electron carrier molecule, the effective formic acid production was observed compared with the other 2,2′-bipyridinium salt derivatives.
- Amao, Yutaka,Abe, Ryutaro,Shiotani, Sachina
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p. 149 - 153
(2015/10/28)
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- Molecular photoconductor with simultaneously photocontrollable localized spins
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UV irradiation reversibly switches a new insulating and nonmagnetic molecular crystal, BPY[Ni(dmit)2]2 (BPY = N,N-ethylene-2,2-bipyridinium; Ni(dmit)2 = bis(1,3-dithiole-2-thione- 4,5-dithiolato)nickelate(III)), into a magnetic conductor. This is possible because the bipyridyl derivative cations (BPY2+) trigger a photochemical redox reaction in the crystal to produce a change of ~10% in the filling of the Ni(dmit)2 valence band, leaving localized spins on the BPY themselves. In the dark, almost all of the BPY molecules are closed-shell cations, and most of the Ni(dmit)2 radical anions form spin-singlet pairs; thus, this material is a diamagnetic semiconductor. Under UV irradiation, a photocurrent is observed, which enhances the conductivity by 1 order of magnitude. Electron spin resonance measurements indicate that the UV irradiation reversibly generates carriers and localized spins on the Ni(dmit)2 and the BPY, respectively. This high photoconductivity can be explained by charge transfer (CT) transitions between Ni(dmit)2 and BPY in the UV region. In other words, the photoconduction and "photomagnetism" can be described as reversible optical control of the electronic states between an ionic salt (BPY2+/[Ni(dmit) 2]-, nonmagnetic insulator) and a CT complex (BPY 2(1-δ)+/[Ni(dmit)2](1-δ)- (δ - 0.1), magnetic conductor) in the solid state.
- Naito, Toshio,Karasudani, Tomoaki,Mori, Shigeki,Ohara, Keishi,Konishi, Kensuke,Takano, Takahiro,Takahashi, Yukihiro,Inabe, Tamotsu,Nishihara, Sadafumi,Inoue, Katsuya
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p. 18656 - 18666
(2013/01/15)
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- NOVEL SPIROPIPERIDINE PROLYLCARBOXYPEPTIDASE INHIBITORS
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Compounds of structural formula (I) are inhibitors of prolylcarboxypeptidase (PrCP). The compounds of the present invention are useful for the prevention and treatment of conditions related to enzymatic activity of PrCP such as abnormal metabolism, including obesity; diabetes; metabolic syndrome; obesity related disorders; and diabetes related disorders.
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Page/Page column 54-55
(2011/11/13)
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- Synthesis and discovery of 2,3-dihydro-3,8-diphenylbenzo[1,4]oxazines as a novel class of potent cholesteryl ester transfer protein inhibitors
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2,3-Dihydro-3,8-diphenylbenzo[1,4]oxazines were identified as a new class of potent cholesteryl ester transfer protein inhibitors. The most potent compound 6a (IC50 = 26 nM) possessed a favorable pharmacokinetic profile with good oral bioavailability in rat (F = 53%) and long human liver microsome stability (t1/2 = 62 min). It increased HDL-C in human CETP transgenic mice and high-fat fed hamsters. The structure and activity relationship of this series will be described in this Letter.
- Wang, Aihua,Prouty, Catherine P.,Pelton, Patricia D.,Yong, Maria,Demarest, Keith T.,Murray, William V.,Kuo, Gee-Hong
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scheme or table
p. 1432 - 1435
(2010/07/06)
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- Conversion of solar energy to chemical energy
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The rate of evolution of hydrogen from water by photochemical process using solar energy has been investigated employing fourteen metal complexes as catalysts, ten electron relays, three electron donors and two co-catalysts in different permutation and combinations. The effect of varying reaction conditions like temperature, concentration and pH have also been investigated for the optimum production of hydrogen by the photochemical cleavage of water molecules.
- Ranganayakulu,Murthy
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scheme or table
p. 309 - 316
(2011/08/09)
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- Revisiting the IspH catalytic system in the deoxyxylulose phosphate pathway: Achieving high activity
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(Chemical Equation Presented) From two C5 isoprene building blocks, isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP), the more than 30000 members of the isoprenoid family are constructed in nature using two biosynthetic pathways, the mevalonate (MVA) pathway and the deoxyxylulose phosphate (DXP) pathway. IspH of the DXP pathway is a protein containing an iron-sulfur cluster and catalyzes a reductive dehydration reaction of the DXP pathway. In the literature, a wide range of Escherichia coli IspH activities have been reported (2.0 nmol min-1 mg-1 to 3.4 μmol min-1 mg-1). For such a broad range of activities, reaction assays were carried out under many different conditions, preventing direct comparison of the activities and determination of the key factor responsible for such a dramatic difference in IspH activities. In this work, we systematically examined the role of redox mediators in IspH catalysis using E. coli IspH as the enzyme and dithionite as the ultimate electron source. Our studies not only suggest the importance of the iron-sulfur cluster but also improve the E. coli IspH activity by nearly 97-fold relative to that from the E. coli NADPH-flavodoxin reductase-flavodoxin system.
- Xiao, Youli,Chu, Lisa,Sanakis, Yiannis,Liu, Pinghua
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supporting information; experimental part
p. 9931 - 9933
(2009/12/08)
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- CF3 oxonium salts, O-(trifluoromethyl)dibenzofuranium salts: In situ synthesis, properties, and application as a real CF3+ species reagent
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(Chemical Equation Presented) We report in situ synthesis of the first CF3 oxonium salts, thermally unstable O-(trifluoromethyl)- dibenzofuranium salts, which furthermore have different counteranions (BF 4-, PF6-, SbF6 -, and Sb2F11-) and ring substituents (tert-butyl, F, and OCH3), by photochemical decomposition of the corresponding 2-(trifluoromethoxy)biphenylyl-2′- diazonium salts at -90 to -100°C. The yields markedly increased in the order of BF4- 6- 6- 2F11-. The CF3 oxonium salts were fully assigned by means of 1H and 19F NMR spectroscopy at low temperature. The CF3 salts decomposed to form CF4 and dibenzofurans. The half-life times at -60°C of the 2-tert-butyl salts having different counteranions were 29 min for BF4- salt 2d, 36 min for PF6- salt 2c, 270 min for SbF6- salt 2a, and 415 min for Sb2F11- salt 2b. Those at -60°C of the Sb2F11- salts having different 2-substituents were 13 min for F salt 3b, 63 min for H (unsubstituted) salt 1b, and 415 min for tert-butyl salt 2b. Thus, the stability of the CF3 oxonium salts increased in the order of BF4- 6 - 6- 2F 11- and F 3+ species source to the direct O- and N-trifluoromethylations of alcohols, phenols, amines, anilines, and pyridines under very mild conditions. The thermal decomposition method with a mixture of diazonium salt 17a and aryl- or alkylsulfonic acids, pyridine, or pyridines having an electron-withdrawing group also afforded CF3O or CF 3N products. The trifluoromethylation mechanism is discussed and an SN2 mechanism containing the transient formation of free CF 3+ is proposed. Thus, the present study has demonstrated that the exceedingly reactive CF3+ species can be generated much easier than the CH3+ species, contrary to the common sense that CF3+ is extremely difficult to generate in solution.
- Umemoto, Teruo,Adachi, Kenji,Ishihara, Sumi
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p. 6905 - 6917
(2008/02/11)
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- The reaction of α,α,α-trifluoromethoxybenzene with AlCl3: A high yield preparation of α,α,α-trichloromethoxybenzene
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α,α,α-Trifluoromethoxybenzene was allowed to react with AlCl3 in CH2Cl2 to afford α,α,α-trichloromethoxybenzene in excellent yield and purity.
- Chen, Qiliang,Xu, Jie,Zhang, Wei
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p. 799 - 801
(2007/10/03)
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- Free-energy dependence of electron-transfer rate constants at Si/liquid interfaces
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The interfacial energetics and kinetics of n-type Si electrodes in contact with a series of one-electron, outer-sphere redox couples were investigated using the differential capacitance vs potential and current density vs potential measurements, respectively. The differential capacitance vs potential measurements were essentially independent of the ac frequency imposed on the interface, with linear Bode plots between ≈103 and ≈105 Hz. The current density vs potential plots exhibited first-order kinetic dependence on the concentration of electrons at the semiconductor surface and a first-order kinetic dependence on the concentration of acceptors in the solution.
- Fajardo,Lewis
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p. 11136 - 11151
(2007/10/03)
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- Antifugal azole compounds
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1,3-Diazolyl-2-propanol derivatives of the formula STR1 wherein X and Y are N or CH, R1 is phenyl, heterocyclyl, heterocyclyl-alkyl, -alkenyl or -alkynyl, optionally substituted, R2 and R3 are hydrogen or alkyl, and R4 and R5 are hydrogen, amino, alkoxyalkyl, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, or alkenyl, or phenyl, phenylalkyl or phenylalkenyl, heterocycyl, heterocyclyalkyl or heterocyclylalkenyl, each optionally substituted, provided that when R1 is optionally substituted phenyl at least one of R1, R4 and R5 is, or contains, a phenyl ring bearing at least one substitutent selected from cyano, cyanoalkyl, nitro, aminocarbonylalkyl, halogeneoalkoxy and radicals of the formulae --CONR6 R7, --NHCOR8 or OR9 as defined herein, and the acid addition salts of compounds which contain a basic substituent; together with processes for their manufacture, pharmaceutical, veterinary and plant antifungal compositions, a method of treating fungal diseases in plants, and the use of the compounds for the manufacture of pharmacuetical or veterinary antifungal compositions.
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- Solid, herbicidal bipyridinium quaternary salt compositions
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Bipyridinium quaternary salt compositions are prepared which are dry, free-flowing, wettable powders. The solid compositions are complexes of the bipyridinium salts and algin.
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- Solid, herbicidal complexes
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Low viscosity heteropolysaccharides, e.g., xanthan gum, S-194, and guar gum, are disclosed. These gums are especially useful in preparing herbicidal compositions.
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- 6-(polyfluoroalkoxyphenyl) pyridazinones, their compositions, synthesis and use
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6-aryl-3[2H]pyridazinones of formula I STR1 in which one of the substituents R1 and R2 denotes hydrogen or (C1-C4)-alkoxy, and the other denotes polyfluoro-(C1-C4)-alkoxy, and their pharmacologically-tolerated salts are suitable as bronchospasmolytic and cardiotonic active compounds. Processes for their preparation and appropriate medicaments are indicated.
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- Acylation du trifluoromethoxybenzene en catalyse HF-BF3
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Friedel and Crafts acylation of trifluoromethoxy- and trifluoromethyl-thiobenzene fails to give ketones in a one step synthesis if chlorinated Lewis acids (AlCl3) are used, because of halogen exchange on the -OCF3 and -SCF3 groups.The use of a fluorinated catalyst system such as HF-BF3 avoids exchange reactions and acylation occurs smoothly under mild conditions: - Low temperature and pressure - High yields (very often >90 percent) - Very high para-regioselectivity.Related reactions such as formylation or sulfonylation can also be achieved under similar conditions.
- Desbois, Michel
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p. 885 - 890
(2007/10/02)
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- 5,6-Dihydro-1,2,4,6-thiatriazin-5-one-1,1-dioxides
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5,6-Dihydro-1,2,4,6-thiatriazin-5-one-1,1-dioxides of the formula STR1 where R1 is hydrogen, a metal atom or an unsubstituted or substituted ammonium radical, R2 is a saturated or unsaturated straight-chain aliphatic radical of up to 10 carbon atoms, a cycloaliphatic radical or 3 to 7 carbon atoms, a branched saturated or unsaturated aliphatic radical of 3 to 10 carbon atoms, a halogen-, alkoxy- or alkylmercapto-substituted aliphatic radical of 2 to 10 carbon atoms tetrahydrofuryl substituted methyl, a cycloalkoxy-substituted aliphatic radical of 4 to 10 carbon atoms, unsubstituted or halogen-substituted benzyl or phenyl, halophenyl, or alkylphenyl of a total of up to 10 carbon atoms, R3 is hydrogen, a straight-chain aliphatic radical of up to 10 carbon atoms, a cycloaliphatic radical of 3 to 7 carbon atoms, a branched aliphatic radical of 3 to 10 carbon atoms, haloalkyl, or alkoxyalkyl of 2 to 10 carbon atoms and X is oxygen and may also be sulfur if R2 is unsubstituted or halogen-substituted benzyl, processes for their preparation, and herbicides containing the above compounds.
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- Herbicidal compositions
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A solid complex of a herbicidal bipyridylium salt in combination with urea or thiourea having the formula: Wherein X represents the bipyridylium salt, A represents urea or thiourea, n is 1, 2 or 4, and m is 0 to 4, its preparation and use are disclosed.
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