- A bio-inspired imidazole-functionalised copper cage complex
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An imidazole-functionalised cage is synthesised that can coordinate to Cu(i). X-ray analysis reveals a T-shaped coordination of copper by the imidazole ligands reminiscent of the coordination geometry found in enzymatic active sites. This cage complex can
- Bete, Sarah C.,Würtele, Christian,Otte, Matthias
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- Dual cobalt-copper light-driven catalytic reduction of aldehydes and aromatic ketones in aqueous media
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We present an efficient, general, fast, and robust light-driven methodology based on earth-abundant elements to reduce aryl ketones, and both aryl and aliphatic aldehydes (up to 1400 TON). The catalytic system consists of a robust and well-defined aminopyridyl cobalt complex active for photocatalytic water reduction and the [Cu(bathocuproine)(Xantphos)](PF6) photoredox catalyst. The dual cobalt-copper system uses visible light as the driving-force and H2O and an electron donor (Et3N or iPr2EtN) as the hydride source. The catalytic system operates in aqueous mixtures (80-60% water) with high selectivity towards the reduction of organic substrates (>2000) vs. water reduction, and tolerates O2. High selectivity towards the hydrogenation of aryl ketones is observed in the presence of terminal olefins, aliphatic ketones, and alkynes. Remarkably, the catalytic system also shows unique selectivity for the reduction of acetophenone in the presence of aliphatic aldehydes. The catalytic system provides a simple and convenient method to obtain α,β-deuterated alcohols. Both the observed reactivity and the DFT modelling support a common cobalt hydride intermediate. The DFT modelled energy profile for the [Co-H] nucleophilic attack to acetophenone and water rationalises the competence of [CoII-H] to reduce acetophenone in the presence of water. Mechanistic studies suggest alternative mechanisms depending on the redox potential of the substrate. These results show the potential of the water reduction catalyst [Co(OTf)(Py2Tstacn)](OTf) (1), (Py2Tstacn = 1,4-di(picolyl)-7-(p-toluenesulfonyl)-1,4,7-triazacyclononane, OTf = trifluoromethanesulfonate anion) to develop light-driven selective organic transformations and fine solar chemicals.
- Call, Arnau,Casadevall, Carla,Acu?a-Parés, Ferran,Casitas, Alicia,Lloret-Fillol, Julio
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p. 4739 - 4749
(2017/07/10)
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- Surface-Plasmon-Mediated Hydrogenation of Carbonyls Catalyzed by Silver Nanocubes under Visible Light
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Plasmonic nanoparticles are exciting and promising candidates for light-activated catalysis. We report herein the use of plasmonic nanocubes for the activation of molecular hydrogen and the hydrogenation of ketones and aldehydes via visible light irradiation at 405 nm, corresponding to the position of the plasmon band of the nanocubes, at 80 °C. Only 1 atm of molecular hydrogen is required to access, using catalytic amounts of silver, primary, and secondary alcohols, with complete chemoselectivty for C=O over C=C reduction. The resulting catalytic system was studied over a scope of 12 compounds. Exposure to other wavelengths, or absence of light failed to provide activity, thus proving a direct positive impact of the plasmonic excitation to the catalytic activity. By varying the irradiation intensity, we studied the relationship between plasmon band excitation and catalytic activity and propose a potential reaction mechanism involving plasmon-activated hot electrons. This study expands the scope of reactions catalyzed by free-standing plasmonic particles and sheds light on H2 activation by silver surfaces.
- Landry, Michael J.,Gellé, Alexandra,Meng, Beryl Y.,Barrett, Christopher J.,Moores, Audrey
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p. 6128 - 6133
(2017/09/15)
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- Selective oxidations of activated alcohols in water at room temperature
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Allylic and benzylic alcohols can be selectively oxidized to their corresponding aldehydes or ketones in water containing nanoreactors composed of the designer surfactant TPGS-750-M. The oxidation relies on catalytic amounts of CuBr, bpy, and TEMPO, with N-methyl-imidazole; air is the stoichiometric oxidant. the Partner Organisations 2014.
- Lipshutz,Hageman,Fennewald,Linstadt,Slack,Voigtritter
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supporting information
p. 11378 - 11381
(2014/11/08)
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- Chemical synthesis and evaluation of 17α-alkylated derivatives of estradiol as inhibitors of steroid sulfatase
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Steroid sulfatase (STS) controls the levels of 3-hydroxysteroids available from circulating steroid sulfates in several normal and malignant tissues. This and the known involvement of active estrogens and androgens in diseases such as breast and prostate cancers thus make STS an interesting therapeutic target. Here we describe the chemical synthesis and characterization of an extended series of 17α-derivatives of estradiol (E2) using different strategies. A variant of the samarium-Barbier reaction with stoichiometric samarium metal and catalytic Kagan reagent formation was used for introducing low reactive benzyl substrates in position 17 of estrone (E1) whereas heterocyclic substrates were metalated and reacted with either the carbonyl or the 17-oxirane of E1. In vitro evaluation of the inhibitory potency of the new compounds against STS identified new inhibitors and allowed a more complete structure-activity relationship study of this family of 17α-derivatives of E2.
- Fournier, Diane,Poirier, Donald
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experimental part
p. 4227 - 4237
(2011/11/12)
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- Hydrogen atom abstraction reactions from tertiary amines by benzyloxyl and cumyloxyl radicals: Influence of structure on the rate-determining formation of a hydrogen-bonded prereaction complex
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A time-resolved kinetic study on the hydrogen atom abstraction reactions from a series of tertiary amines by the cumyloxyl (CumO?) and benzyloxyl (BnO?) radicals was carried out. With the sterically hindered triisobutylamine, comparable hydrogen atom abstraction rate constants (kH) were measured for the two radicals (kH(BnO ?)/kH(CumO?) = 2.8), and the reactions were described as direct hydrogen atom abstractions. With the other amines, increases in kH(BnO?)/kH(CumO ?) ratios of 13 to 2027 times were observed. kH approaches the diffusion limit in the reactions between BnO? and unhindered cyclic and bicyiclic amines, whereas a decrease in reactivity is observed with acyclic amines and with the hindered cyclic amine 1,2,2,6,6-pentamethylpiperidine. These results provide additional support to our hypothesis that the reaction proceeds through the rate-determining formation of a C-H/N hydrogen-bonded prereaction complex between the benzyloxyl α-C-H and the nitrogen lone pair wherein hydrogen atom abstraction occurs, and demonstrate the important role of amine structure on the overall reaction mechanism. Additional mechanistic information in support of this picture is obtained from the study of the reactions of the amines with a deuterated benzyloxyl radical (PhCD2O?, BnO?- d2) and the 3,5-di-tert-butylbenzyloxyl radical.
- Salamone, Michela,Dilabio, Gino A.,Bietti, Massimo
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p. 6264 - 6270
(2011/10/08)
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- Controlled submolecular translational motion in synthesis: A mechanically interlocking auxiliary
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Sew simple: How can you put a molecular bead on a thread when no recognition elements exist between them? A mechanically interlocking auxiliary assembles the macrocycle around a template, controlled submolecular translation moves the ring over the desired
- Hannam, Jeffrey S.,Lacy, Stephen M.,Leigh, David A.,Saiz, Carlos G.,Slawin, Alexandra M. Z.,Stitchell, Sheila G.
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p. 3260 - 3264
(2007/10/03)
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- Facile synthesis of rotaxanes through condensation reactions of DCC-[2]rotaxanes
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matrix presented In this Letter, we present an easy method for the synthesis of rotaxanes using a novel DCC-[2]rotaxane. The DCC-[2]rotaxane is composed of dibenzo-24-crown-8 ether, an amino acid tether, and di-tert-butyl phenyl rings as blocking groups.
- Zehnder II, Donald W.,Smithrud, David B.
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p. 2485 - 2487
(2007/10/03)
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- Trienoic retinoid compounds and methods
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Novel trienoic retinoid compounds having activity for retinoic acid receptors and retinoid X receptors are provided. Also provided are pharmaceutical compositions incorporating such compounds and methods for their use.
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- Binding activity of substituted benzyl derivatives of chloronicotinyl insecticides to housefly-head membranes, and its relationship to insecticidal activity against the housefly Musca domestica
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Variously substituted benzyl derivatives of chloronlcotinyl insecticides were synthesized with a wide range of substituents including halogens, NO2, CN, CF3 and small alkyl and alkoxy groups at the ortho, meta and para positions, as well as multiple-substituted benzyl analogues. Their binding activity to the α-bungarotoxin binding site in housefly (Musca domestica) head membrane preparations was measured. Among the compounds tested, the activity of the meta-CN derivative was the highest, being 20-100 times higher than those of imidacloprid, acetamiprid and nitenpyram. The synergized insecticidal activity against houseflies was also measured for selected compounds with the metabolic inhibitor, NIA16388 (propargyl propyl phenylphosphonate). For the nitromethylene analogues, including both benzyl and pyridylmethyl analogues, higher binding activity usually resulted in higher insecticidal activity. (C) 2000 Society of Chemical Industry.
- Nishiwaki, Hisashi,Nakagawa, Yoshiaki,Takeda, David Y.,Okazawa, Atsushi,Akamatsu, Miki,Miyagawa, Hisashi,Ueno, Tamio,Nishimura, Keiichiro
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p. 875 - 881
(2007/10/03)
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- Trienoic retinoid compounds and methods
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Novel trienoic compounds having activity for retinoic acid receptors and retinoid X receptors are provided. Also provided are pharmaceutical compositions incorporating such compounds and methods for their use.
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- Analogues of capsaicin with agonist activity as novel analgesic agents: Structure-activity studies. 4. Potent, orally active analgesics
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Structural features of three regions of the capsaicin molecule necessary for agonist properties were delineated by a previously reported modular approach. These in vitro agonist effects were shown to correlate with analgesic potency in rodent models. Comb
- Wrigglesworth, Roger,Walpole, Christopher S. J.,Bevan, Stuart,Campbell, Elizabeth A.,Dray, Andy,Hughes, Glyn A.,James, Iain,Masdin, Kay J.,Winter, Janet
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p. 4942 - 4951
(2007/10/03)
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- Photolytic double decarbonylation route to highly substituted indenes and benzene derivatives
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UV irradiation of cyclohexane solution of a 4,7-ethanoindene-8,9-dione derivative led to a facile extrusion of two molecules of carbon monoxide to give a dihydroindene along with its dehydrogenated product, a methylene indene (benzofulvene). The inseparab
- Thomas, Abraham,Anilkumar, Gopinathan,Nair, Vijay
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p. 2481 - 2488
(2007/10/03)
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- DERIVATIVES OF AROMATIC CYCLIC ALKYLETHERS
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The present invention provides compounds of the formula: and the pharmaceutically acceptable salts thereof, wherein: R1 and R2 are each alkyl; n is an integer of from 1 to 4; x is oxygen or -(CH2)m-; m is an integer of from 1 to 3; y is oxygen or sulfur; and p is an integer of from 1 to 4. These compounds are inhibitors of COX-I and/or COX-II, and are useful for the treatment of inflammation-associated disorders. The present invention also provides pharmaceutical compositions comprising a therapeutically-effective amount of a compound of Formula I in combination with a pharmaceutically-acceptable carrier, and a method for treating inflammation-associated disorders in an animal comprising administering a therapeutically-effective amount of a compound of Formula I to the animal
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