- Rh/TiO2-Photocatalyzed Acceptorless Dehydrogenation of N-Heterocycles upon Visible-Light Illumination
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TiO2 is an effective and extensively employed photocatalyst, but its practical use in visible-light-mediated organic synthesis is mainly hindered by its wide band gap energy. Herein, we have discovered that Rh-photodeposited TiO2 nanoparticles selectively dehydrogenate N-heterocyclic amines with the concomitant generation of molecular hydrogen gas in an inert atmosphere under visible light (λmax = 453 nm) illumination at room temperature. Initially, a visible-light-sensitive surface complex is formed between the N-heterocycle and TiO2. The acceptorless dehydrogenation of N-heterocycles is initiated by direct electron transfer from the HOMO energy level of the amine via the conduction band of TiO2 to the Rh nanoparticle. The reaction condition was optimized by examining different photodeposited noble metals on the surface of TiO2 and solvents, finding that Rh0 is the most efficient cocatalyst, and 2-propanol is the optimal solvent. Structurally diverse N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, indolines, and others bearing electron-deficient as well as electron-rich substituents underwent the dehydrogenation in good to excellent yields. The amount of released hydrogen gas evinces that only the N-heterocyclic amines are oxidized rather than the dispersant. This developed method demonstrates how UV-active TiO2 can be employed in visible-light-induced synthetic dehydrogenation of amines and simultaneous hydrogen storage applications.
- Bahnemann, Detlef W.,Balayeva, Narmina O.,Dillert, Ralf,Mamiyev, Zamin,Zheng, Nan
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p. 5542 - 5553
(2020/08/25)
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- Optical p Ka Control in a Bifunctional Iridium Complex
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There are few ways to switch a catalyst's reactivity on or off, or change its selectivity, with external radiation; many of these involve photochemical activation of a catalyst. In the case of homogeneous late-transition-metal catalysts, the metal complex itself is frequently the chromophore involved in such reactivity switching. We show here a base-pendant ligand-metal bifunctional scaffold wherein a photobase, a compound that becomes more basic in the excited state (pKa a?), is used to switch the proton acceptor ability on an active site of the complex. The system differs from those with metal-centered chromophores, because the photobase operates independently of the metal. While excellent progress has been made in photoacid chemistry, neither a photoacid nor a photobase has been designed into the structure of a transition-metal catalyst where the metal is not part of the chromophore. We find that quinoline is an efficient photobase that preserves its unique properties in the close proximity of an iridium center: the efficacy of the photobase (9.3 a? a control in a transition-metal complex.
- Demianets, Ivan,Hunt, Jonathan R.,Dawlaty, Jahan M.,Williams, Travis J.
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supporting information
p. 200 - 204
(2019/01/21)
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- GLYCOSIDASE INHIBITORS
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Compounds of formula (I) wherein A, R, W, Q, n and m have the meaning according to the claims can be employed, inter alia, for the treatment of tauopathies and Alzheimer's disease.
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Page/Page column 87
(2016/03/22)
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- Rhodium-Catalyzed Interconversion of Quinolinyl Ketones with Boronic Acids via C-C Bond Activation
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A rhodium-catalyzed cross-coupling of aryl and aliphatic quinolinyl ketones with boronic acids has been developed. Proceeding via quinoline-directed carbon-carbon σ bond activation, the transformation demonstrates tolerance of a range of functional groups
- Dennis, Joseph M.,Compagner, Chad T.,Dorn, Stanna K.,Johnson, Jeffrey B.
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p. 3334 - 3337
(2016/07/26)
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- Exploring the Catalytic Reactivity of Nickel Phosphine-Phosphite Complexes
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In this study, we present an investigation into various nickel phosphite and phosphite-phosphine complexes for use in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions and the ammonia arylation reaction. In these coupling reactions, it was discovered that the Ni[P(OEt)3]4, (dppf)Ni[P(OPh)3]2, and (binap)Ni[P(OPh)3]2 catalysts were the most effective. In addition, an optimisation process for these catalytic systems as well as functional group compatibility are discussed.
- Kampmann, Sven S.,Man, Nikki Y. T.,McKinley, Allan J.,Koutsantonis, George A.,Stewart, Scott G.
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p. 1842 - 1853
(2015/12/26)
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- Quinoline and phenanthroline preparation starting from glycerol via improved microwave-assisted modified Skraup reaction
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An efficient "green" modified Skraup reaction in neat water was developed using inexpensive, abundant and environmentally-friendly glycerol under microwave irradiation conditions. Starting from aniline derivatives, various quinolines were obtained in 10-66% yields. The use of nitroaniline led to the corresponding phenanthrolines in 15-52% yields, respectively. This journal is the Partner Organisations 2014.
- Saggadi, Hanen,Luart, Denis,Thiebault, Nicolas,Polaert, Isabelle,Estel, Lionel,Len
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p. 21456 - 21464
(2014/06/10)
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- Direct exchange of a ketone methyl or aryl group to another aryl group through ciC bond activation assisted by rhodium chelation
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Swapped: Commercially available quinolinone derivatives (1 or 2, see scheme) were reacted with arylboronic acids in the presence of a RhI complex to give aryl(quinolin-8-yl)methanone products 3 in medium to good yields. A mechanism that involves the in situ oxidation of RhI to RhIII by O2 in the presence of CuI was proposed. Copyright
- Wang, Jingjing,Chen, Weiqiang,Zuo, Sujing,Liu, Lu,Zhang, Xinrui,Wang, Jianhui
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p. 12334 - 12338
(2013/02/23)
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- CALCIUM RECEPTOR MODULATING ARYLALKYLAMINES
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The compounds of the invention are represented by the following general structure (I) or a pharmaceutically acceptable salt thereof, and compositions containing them, wherein the variables are defined herein, and their use to reduce or inhibit PTH secretion, including methods for reducing or inhibiting PTH secretion and methods for treatment or prophylaxis of diseases associated with bone disorders, such as osteoporosis, or associated with excessive secretion of PTH, such as hyperparathyroidism. The subject invention also relates to processes for making such compounds as well as to intermediates useful in such processes.
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- Syntheses of acetylquinolines and acetylisoquinolines via palladium-catalyzed coupling reactions
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Acetylquinolines and acetylisoquinolines were obtained from the corresponding chloro-, bromo- or trifluoromethylsulfonyloxy-heteroaromatics via four different palladium-catalyzed coupling reactions: (i) Stille coupling with tri(n-butyl)-1-ethoxyvinylstannane; (ii) Negishi coupling with 1-ethoxyvinylzinc chloride; (iii) cross-coupling with tri(1-ethoxyvinyl)indium; (iv) Heck arylation of n-butyl vinyl ether.
- Legros, Jean-Yves,Primault, Ga?lle,Fiaud, Jean-Claude
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p. 2507 - 2514
(2007/10/03)
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