- Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-Supported Catalysts in Tandem Reactions
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Nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed, in the presence of an aqueous solution of TEMPO-oxidized nanocellulose (0.01 wt%), the reduction of a wide range of nitroarenes and aliphatic nitro compounds. Here we describe how the modified nanocellulose has a stabilizing effect on the catalyst that enables low loading of the nickel salt pre-catalyst. Ni-B prepared in situ from a methanolic solution was also used to develop a greener and facile reduction of organic azides, offering a substantially lowered catalyst loading with respect to reported methods in the literature. Both aromatic and aliphatic azides were reduced, and the protocol is compatible with a one-pot Boc-protection of the obtained amine yielding the corresponding carbamates. Finally, bacterial crystalline nanocellulose was chosen as a support for the Ni-B catalyst to allow an easy recovery step of the catalyst and its recyclability for new reduction cycles.
- Proietti, Giampiero,Prathap, Kaniraj Jeya,Ye, Xinchen,Olsson, Richard T.,Dinér, Peter
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supporting information
p. 133 - 146
(2021/11/04)
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- Harnessing Endogenous Formate for Antibacterial Prodrug Activation by in cellulo Ruthenium-Mediated Transfer Hydrogenation Reaction
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The abundance and evolving pathogenic behavior of bacterial microorganisms give rise to antibiotic tolerance and resistance which pose a danger to global public health. New therapeutic strategies are needed to keep pace with this growing threat. We propose a novel approach for targeting bacteria by harnessing formate, a cell metabolite found only in particular bacterial species, to activate an antibacterial prodrug and selectively inhibit their growth. This strategy is premised on transfer hydrogenation reaction on a biorthogonal substrate utilizing native formate as the hydride source as a means of uncaging an antibacterial prodrug. Using coordination-directed 3-component assembly to prepare a library of 768 unique Ru–Arene Schiff-base complexes, we identified several candidates that efficiently reduced sulfonyl azide functional group in the presence of formate. This strategy paves the way for a new approach of targeted antibacterial therapy by exploiting unique bacterial metabolites.
- Ang, Wee Han,Shen, Linghui,Weng, Cheng
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supporting information
p. 9314 - 9318
(2020/04/29)
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- Identification of highly potent and selective Cdc25 protein phosphatases inhibitors from miniaturization click-chemistry-based combinatorial libraries
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Cell division cycle 25 (Cdc25) protein phosphatases play key roles in the transition between the cell cycle phases and their association with various cancers has been widely proven, which makes them ideal targets for anti-cancer treatment. Though several Cdc25 inhibitors have been developed, most of them displayed low activity and poor subtype selectivity. Therefore, it is extremely important to discover novel small molecule inhibitors with potent activities and significant selectivity for Cdc25 subtypes, not only served as drugs to treat cancer but also to probe its mechanism in transitions. In this study, miniaturized parallel click chemistry synthesis via CuAAC reaction followed by in situ biological screening were used to discover selective Cdc25 inhibitors. The bioassay results showed that compound M2N12 proved to be the most potent Cdc25 inhibitor, which also act as a highly selective Cdc25C inhibitor and was about 9-fold potent than that of NSC 663284. Moreover, M2N12 showed remarkable anti-growth activity against the KB-VIN cell line, equivalent to that of PXL and NSC 663284. An all-atom molecular dynamics (MD) simulation approach was further employed to probe the significant selectivity of M2N12 for Cdc25C relative to its structural homologs Cdc25A and Cdc25B. Overall, above results make M2N12 a promising lead compound for further investigation and structural modification.
- Jing, Lanlan,Wu, Gaochan,Hao, Xia,Olotu, Fisayo A.,Kang, Dongwei,Chen, Chin Ho,Lee, Kuo-Hsiung,Soliman, Mahmoud E.S.,Liu, Xinyong,Song, Yuning,Zhan, Peng
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- Glucose promoted facile reduction of azides to amines under aqueous alkaline conditions
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A quick and efficient method for the reduction of azides to amines in water using d-glucose and KOH as green reagents is reported. The protocol is simple, inexpensive, scalable, and can be applied to different aromatic, heteroaromatic and sulphonyl azides. A high level of chemoselectivity is observed for azide reduction in the presence of other reducible functionalities like cyano, nitro, ether, ketone, amide and acid. The reaction gets completed in a short time (5-20 minutes), and furnishes the amines in high yield (85-99%). Unlike conventional hydrogenations, this reduction protocol does not require any metal catalyst, elaborate experimental setup or use of high-pressure equipment.
- Chandna, Nisha,Kaur, Fatehjeet,Kumar, Shobhna,Jain, Nidhi
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supporting information
p. 4268 - 4271
(2017/09/29)
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- Design, Synthesis, and Evaluation of Triazole Derivatives That Induce Nrf2 Dependent Gene Products and Inhibit the Keap1-Nrf2 Protein-Protein Interaction
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The transcription factor Nrf2 regulates the expression of a large network of cytoprotective and metabolic enzymes and proteins. Compounds that directly and reversibly inhibit the interaction between Nrf2 and its main negative regulator Keap1 are potential pharmacological agents for a range of disease types including neurodegenerative conditions and cancer. We describe the development of a series of 1,4-diphenyl-1,2,3-triazole compounds that inhibit the Nrf2-Keap1 protein-protein interaction (PPI) in vitro and in live cells and up-regulate the expression of Nrf2-dependent gene products.
- Bertrand, Hélène C.,Schaap, Marjolein,Baird, Liam,Georgakopoulos, Nikolaos D.,Fowkes, Adrian,Thiollier, Clarisse,Kachi, Hiroko,Dinkova-Kostova, Albena T.,Wells, Geoff
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supporting information
p. 7186 - 7194
(2015/10/05)
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- A fragment based click chemistry approach towards hybrid G-quadruplex ligands: Design, synthesis and biophysical evaluation
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A library of hybrid oxazole-triazole based compounds containing contiguously linked aromatic units were synthesised as G-quadruplex binding ligands. The design of these ligands was based upon combining features of our first generation of G-quadruplex bis-
- Ritson, Dougal J.,Moses, John E.
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experimental part
p. 197 - 203
(2012/01/31)
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- Copper(II)-catalyzed conversion of aryl/heteroaryl boronic acids, boronates, and trifluoroborates into the corresponding azides: Substrate scope and limitations
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We report the copper(II)-catalyzed conversion of organoboron compounds into the corresponding azide derivatives. A systematic series of phenylboronic acid derivatives is evaluated to examine the importance of steric and electronic effects of the sub-stituents on reaction yield as well as functional group compatibility. Heterocyclic substrates are also shown to participate in this mild reaction while compounds incorporating B-C(sp3) bonds are unreactive under the reaction conditions. The copper(II)-catalyzed boronic acid-azide coupling reaction is further extended to both boronate esters and potassium organotrifluoroborate salts. The method described herein complements existing procedures for the preparation of aryl azides from the respective amino, triazene, and halide derivatives and we expect that it will greatly facilitate copper- and ruthenium-catalyzed azide-alkyne cycloaddition reactions for the preparation of diversely functionalized 1-aryl- or 1-heteroaryl-1,2,3- triazoles derivatives. Georg Thieme Verlag Stuttgart.
- Grimes, Kimberly D.,Gupte, Amol,Aldrich, Courtney C.
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experimental part
p. 1441 - 1448
(2010/10/03)
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- Synthesis of aryl azides via post-cleavage modification of polymer-bound triazenes
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Starting from immobilized arenes on the triazene T1 linker resin, cleavage was achieved by trifluoroacetic acid in the presence of trimethylsilyl azide to obtain aryl azides in good yields and excellent purities. A novel cleavage protocol has been introduced and analytical and preparative applications have been presented.
- Avemaria, Frank,Zimmermann, Viktor,Br?se, Stefan
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p. 1163 - 1166
(2007/10/03)
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- Ring-expansion of Azidobenzenesulphonamides and Azidobenzamides
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4-Azidobenzenesulphonamides and 2- and 4-azidobenzamides undergo phototransformation to 2-alkoxy-3H-azepines in alcohols but the yields are low.Ring-expansion of 4-azidobenzenesulphonamide and 4-azidobenzenesulphonylguanidine in aqueous tetrahydrofuran to 3H-azepin-2(1H)-ones proceeds via a singlet nitrene pathway; thermolysis of 4-azidobenzenesulphonamide in aqueous dioxane gave only the triplet-derived product, sulphanilamide.Efficient de-azidation of 4-azidobenzesulphonamides and 4-azidobenzamides can be accomplished by heating the azides at 105 deg C in hydrazine hy drate.The crystallographic analysis of 5-sulphamoyl-3H-azepin-2(1H)-one shows the molecule to be non-planar with the azepine ring puckered in a boat form.The lactam configuration is confirmed with the carbonyl group having a bond length of 1.231 Angstroem.
- Brown, Thomas B.,Lowe, Philip R.,Schwalbe, Carl H.,Stevens, Malcolm F.G.
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p. 2485 - 2490
(2007/10/02)
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