- Synthesis of Nitro-Aryl Functionalised 4-Amino-1,8-Naphthalimides and Their Evaluation as Fluorescent Hypoxia Sensors
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Fluorescent sensors are a vital research tool, enabling the study of intricate cellular processes in a sensitive manner. The design and synthesis of responsive and targeted probes is necessary to allow such processes to be interrogated in the cellular environment. This remains a challenge, and requires methods for functionalisation of fluorophores with multiple appendages for sensing and targeting groups. Methods to synthesise more structurally complex derivatives of fluorophores will expand their potential scope. Most known 4-amino-1,8-naphthalimides are only functionalised at imide and 4-positions, and structural modifications at additional positions will increase the breadth of their utility as responsive sensors. In this work, methods for the incorporation of a hypoxia sensing group to 4-amino-1,8-naphthalimide were evaluated. An intermediate was developed that allowed us to incorporate a sensing group, targeting group, and ICT donor to the naphthalimide core in a modular fashion. Synthetic strategies for attaching the hypoxia sensing group and how they affected the fluorescence of the naphthalimide were evaluated by photophysical characterisation and time-dependent density functional theory. An extracellular hypoxia probe was then rationally designed that could selectively image the hypoxic and necrotic region of tumour spheroids. Our results demonstrate the versatility of the naphthalimide scaffold and expand its utility. This approach to probe design will enable the flexible, efficient generation of selective, targeted fluorescent sensors for various biological purposes.
- Adair, Liam D.,Trinh, Natalie,Vérité, Pauline M.,Jacquemin, Denis,Jolliffe, Katrina A.,New, Elizabeth J.
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- Discovery of Cell-Permeable O-GlcNAc Transferase Inhibitors via Tethering in Situ Click Chemistry
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O-GlcNAc transferase (OGT) is a key enzyme involved in dynamic O-GlcNAcylation of nuclear and cytoplasmic proteins similar to phosphorylation. Discovery of cell-permeable OGT inhibitors is significant to clarify the function and regulatory mechanism of O-GlcNAcylation. This will establish the foundation for the development of therapeutic drugs for relevant diseases. Here, we report two cell-permeable OGT inhibitors (APNT and APBT), developed from low-activity precursors (IC50 > 1 mM) via “tethering in situ click chemistry (TISCC)”. Both of them were able to inhibit O-GlcNAcylation in cells without significant effects on cell viability. Unusual noncompetitive inhibition of OGT was helpful to discover novel inhibitors and explore the regulatory mechanism of OGT. The development of these molecules validates that TISCC can be utilized to discover novel lead compounds from components that exhibited very weak binding to the target.
- Wang, Yue,Zhu, Jingjing,Zhang, Lianwen
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- Copper catalyzed synthesis of aryl azides from aryl bromides and sodium azide
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Aryl azides were synthesized using heterogeneous porous Cu catalyst via a coupling reaction of aryl bromides with sodium azide under mild conditions. The catalyst can be recycled in five times without significant loss of their catalytic activity.
- Zeng, Ming,Yang, Yu Hua,Li, Jin Jing,Chen, Ying,Cui, Dong Mei,Zhang, Chen
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- Synthesis of aryl azides from aryl halides promoted by Cu2O/tetraethylammonium prolinate
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An efficient approach to aryl azides, in short reaction times and good to excellent yields, has been developed via the reaction of aryl halides with sodium azide under Cu2O/tetraethylammonium prolinate catalysis.
- Hajipour, Abdol R.,Mohammadsaleh, Fatemeh
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- Synthesis of aryl azides and vinyl azides via proline-promoted CuI-catalyzed coupling reactions.
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The coupling reaction of aryl halides or vinyl iodide with sodium azide under catalysis of CuI/L-proline works at relatively low temperature to provide aryl azides or vinyl azides in good to excellent yields.
- Zhu, Wei,Ma, Dawei
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- Chloromethylated polystyrene supported copper (II) bis–thiazole complex: Preparation, characterization and its application as a heterogeneous catalyst for chemoselective and homoselective synthesis of aryl azides
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This work deals the synthesis of aryl azides catalyzed by heterogeneous copper (II) complex of 3,5–bis (2–benzothiazolyl) pyridine, [Cu (II)(BTP)(OTf)2], immobilized on chloromethylated polystyrene, [Cu (II)(BTP)(OTf)2]@CMP. The prepared catalyst was characterized by different analytical techniques such as X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (SEM), energy dispersive X–ray spectroscopy (EDX), elemental analysis, and FT-IR and UV–Vis spectroscopic methods. This catalytic system showed excellent activity in the synthesis of aryl azides by the reaction of aryl halides with sodium azide in the presence of catalytic amounts of [Cu (II)(BTP)(OTf)2]@CMP. Moreover, this unique catalyst could be recovered easily and reused several times without any considerable loss of its catalytic activity.
- Dehbanipour, Zahra,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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- Selective recognition of: C-MYC G-quadruplex DNA using prolinamide derivatives
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Herein we report the design, synthesis, biophysical and biological evaluation of triazole containing prolinamide derivatives as selective c-MYC G-quadruplex binding ligands. A modular synthetic route has been devised for prolinamide derivatives using a copper(i) catalyzed azide-alkyne cycloaddition (CuAAC). The F?rster resonance energy transfer (FRET) melting assay indicates that prolinamide trimers can significantly stabilize G-quadruplex structures over duplex DNA compared to prolinamide dimers. The fluorescent intercalator displacement (FID) assay shows that a trimer with prolinamide side chains at the para-position of the benzene ring can discriminate between different quadruplex structures and exhibits the highest binding affinity towards the c-MYC G-quadruplex structure. Molecular modeling studies reveal that the prolinamide trimer stacks upon the terminal G-quartet of the c-MYC G-quadruplex. Atomic force microscopy (AFM) analysis reveals that the tris-prolinamide ligand can be used to regulate the assembly of novel supramolecular nanoarchitectures. Further, in vitro cellular studies with human hepatocellular carcinoma (HepG2) cells indicate that the tris-prolinamide derivatives can inhibit cell proliferation and reduce c-MYC expression in cancer cells.
- Chauhan, Ajay,Paladhi, Sushovan,Debnath, Manish,Dash, Jyotirmayee
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- Capping Strategies for Covalent Template-Directed Synthesis of Linear Oligomers Using CuAAC
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Covalent templating provides an attractive solution to the controlled synthesis of linear oligomers because a template oligomer can be used to define the precise length and sequence of the product. If the monomer units are attached to the template using kinetically inert covalent bonds it should be possible to operate at high dilution to favor intramolecular over intermolecular reaction. However, for oligomerization reactions using copper-catalyzed azide alkyne cycloaddition (CuAAC) this is not the case. The rate-limiting step is formation of an activated copper complex, so any alkyne that is activated by copper reacts rapidly with the nearest available azide. As a result, every time a chain end alkyne is activated, rapid intermolecular reaction takes place with a different oligomer leading to the formation of higher order products. It proved possible to block these intermolecular reactions by adding an excess of an azide capping agent that intercepts the chain end of the growing oligomer on the template. By adjusting the concentration of the capping agent to compete effectively with the unwanted intermolecular reactions without interfering with the desired intramolecular reactions, it was possible to obtain quantitative yields of copy strands from covalent template-directed oligomerization reactions. Remarkably, the capping agent could also be used to control the stereochemistry of the duplex formed in the templated oligomerization reaction to give exclusively the antiparallel product.
- Ciaccia, Maria,Nú?ez-Villanueva, Diego,Hunter, Christopher A.
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- A highly effective green catalyst Ni/Cu bimetallic nanoparticles supported by dendritic ligand for chemoselective oxidation and reduction reaction
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The highly active Ni/Cu bimetallic nanoparticles (NPs) of the different molar ratios of Ni and Cu (1:1, 1:3, 3:1) assisted by dendritic ligand 2,4,6-Tris (di-4-chlorobenzamido)-1,3-diazine were synthesized successfully confirmed by Scanning Electron Microscopy (SEM), Electron Diffraction X-ray (EDX), X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM) analysis. These NPs were studied as a heterogeneous catalyst for the chemoselective oxidation of alcohol to the corresponding aldehyde at 30?min and chemoselective reduction of aromatic nitro substituents to the corresponding amino substituents at 20?min, while the Ni/Cu (3:1) NPs were found to be the most effective among other Ni/Cu?(1:1)?and Ni/Cu?(1:3)?NPs at room temperature under mild conditions. The Ni/Cu (3:1) NPs can be recycled for at least five successive runs with no perceptible decrease in catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
- Islam, Md. Sayedul,Khan, Md. Wahab
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p. 2353 - 2369
(2021/01/07)
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- Unsymmetric Bistable [c2]Daisy Chain Rotaxanes which Combine Two Types of Electroactive Stoppers
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Mechanically interlocked molecules (MIMs) have emerged as intriguing building blocks for the construction of stimuli-responsive devices and materials. A particularly interesting and well-implemented subclass of MIMs is composed of symmetric bistable [c2]daisy chain rotaxanes. Topologically, they consist in the double thread of two symmetric macrocycles that are covalently linked to an axle bearing two switchable stations and a bulky stopper to avoid unthreading. Herein we report the synthesis and characterization of a series of unsymmetric bistable [c2]daisy chain rotaxanes that present two different electroactive units as stoppers (an electron donor triarylamine and an electron acceptor perylene bisimide unit). Using a combination of 1D and 2D NMR along with cyclic voltammetry, we demonstrate that the pH actuation of the mechanical bond can be used to modulate the electrochemical properties of the bistable [c2]daisy chain rotaxanes when switching between the contracted and extended forms.
- Wolf, Adrian,Cid, Juan-José,Moulin, Emilie,Niess, Frédéric,Du, Guangyan,Goujon, Antoine,Busseron, Eric,Ruff, Adrian,Ludwigs, Sabine,Giuseppone, Nicolas
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supporting information
p. 3421 - 3432
(2019/03/26)
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- Controlled Transformations of Aryl Halides in a Flow System: Selective Synthesis of Aryl Azides and Aniline Derivatives
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Copper-mediated nitrogenation of aryl halides with sodium azide can result in either aryl azides or aniline derivatives. The selectivity of the transformation is highly dependent on reaction time and temperature, which led to contradictory literature results with respect to product selectivity and the conditions applied. The advantages of a strictly controlled flow reactor environment were exploited in order to facilitate selective haloarene transformations. Reaction conditions were carefully investigated to understand their role on product selectivity. Aryl azides and aryl amines were successfully prepared from the same starting materials using the same auxiliaries by means of precise control over residence time and reaction temperature, thereby ensuring time-, cost- and atom-efficient syntheses. (Figure presented.).
- Georgiádes, ádám,?tv?s, Sándor B.,Fül?p, Ferenc
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p. 1841 - 1849
(2018/04/09)
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- Mild-Base-Promoted Arylation of (Hetero)Arenes with Anilines
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Transition metal-free radical arylation of heteroarenes is achieved at room temperature by simply adding aqueous sodium carbonate to a solution of the corresponding heteroarene and arenediazonium salt, which can even be formed in situ. Such an easy, inexpensive and mild methodology has been optimized and applied to the expeditious modification of interesting molecular cores like naphthylimide or bisthienylcyclopentenes.
- Monzón, Diego M.,Santos, Tanausú,Pinacho-Crisóstomo,Martín, Víctor S.,Carrillo, Romen
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p. 325 - 333
(2018/01/15)
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- Synthesis of sulfamide analogues of deoxthymidine monophosphate as potential inhibitors of mycobacterial cell wall biosynthesis
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The recently discovered enzyme Mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt), which catalyses the phosphorylation of deoxythymidine monophosphate (dTMP) to give deoxythymidine diphosphate (dTDP), is indispensable for the growth and survival of M. tuberculosis as it plays an essential role in DNA synthesis. Inhibition of TMPKmt is an attractive avenue for the development of novel anti-tuberculosis agents. Based on the premise that sulfamide may be a suitable isostere of phosphate, deoxythymidine analogues comprising various substituted sulfamides at C5′ were modelled in silico into the active site of TMPKmt (PDB accession code: 1N5K) using induced-fit docking methods. A selection of modelled compounds was synthesized, and their activity as inhibitors of TMPKmt was evaluated. Three compounds showed competitive inhibition of TMPKmt in the micromolar range (10–50 μM). Compounds were tested in vitro for anti-mycobacterial activity against M. smegmatis: three compounds showed weak anti-mycobacterial activity (MIC 250 μg/mL).
- Suthagar, Kajitha,Jiao, Wanting,Munier-Lehmann, Hélène,Fairbanks, Antony J.
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- Rhenium Complexes Based on an N2O Tridentate Click Scaffold: From Synthesis, Structural and Theoretical Characterization to a Radiolabelling Study
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A general synthetic approach to a novel range of semirigid bifunctional chelating agents (BCAs) that include an aromatic ring and a triazolyl moiety in the chelating unit has been investigated for the fac-[M(CO)3]+core (M =185/187Re or188Re). The strategy includes the facile preparation of these N2O ligands bearing various functionalized arms (carboxylate, terminal alkyne, aromatic amine). The reaction of commercial [Re(CO)5Cl] {or a freshly prepared [Re(OH2)3(CO)3]+precursor} with our BCAs in methanol led to the formation of stable neutral tricarbonylrhenium complexes of general formula [Re(CO)3(L)] (LH = 5, 10, 11) in high yields. These compounds were characterized by IR and NMR spectroscopy, mass spectrometry, electrochemistry, and X-ray crystallography for [Re(CO)3(5–H)] and [Re(CO)3(11–H)] as well as by DFT calculations. The analogous rhenium-188 complexes [188Re(CO)3(5)] and [188Re(CO)3(11–H)] were also prepared, in acceptable to excellent yields, by the reaction of 5 or 11 with the fac-[188Re(OH2)3(CO)3]+precursor in methanol at 80 °C. The structural identities of the radioactive complexes were assessed by HPLC studies. The good affinity of these click ligands for the ReIcore combined with the ease of their derivatization make this chelating system promising for the conception of target-specific radiopharmaceuticals for therapeutic purposes.
- Eychenne, Romain,Guizani, Sihem,Wang, Jin-Hui,Picard, Claude,Malek, Nadia,Fabre, Paul-Louis,Wolff, Mariusz,Machura, Barbara,Saffon, Nathalie,Lepareur, Nicolas,Benoist, Eric
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- Highly chemoselective reduction of azides to amines by Fe(0) nanoparticles in water at room temperature
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A highly chemoselective reduction of aryl, heteroaryl, acyl and sulfonyl azides to the corresponding amines has been achieved by Fe(0) nanoparticles in water at room temperature in the absence of external hydride source. Several readily reducible functionalities including alkene, alkyne, S-S linkage, OTBDMS remain unaffected during reduction.
- Panja, Subir,kundu, Debasish,Ahammed, Sabir,Ranu, Brindaban C.
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supporting information
p. 3457 - 3460
(2017/08/10)
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- Design, combinatorial synthesis and biological evaluations of novel 3-amino-1'-((1-aryl-1H-1,2,3-triazol-5-yl)methyl)-2'-oxospiro[benzo[a] pyrano[2,3-c]phenazine-1,3'-indoline]-2-carbonitrile antitumor hybrid molecules
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A combinatorial chemical library of fifty-nine novel 3-amino-1'-((1-aryl-1H-1,2,3-triazol-5-yl)methyl)-2'-oxospiro[benzo[a]pyrano[2,3-c]phenazine-1,3'-indoline]-2-carbonitrile, designed as hybrid molecules of phenazine, pyran, indole and 1,2,3-triazole pharmacophores, were constructed in this study. Cytotoxic evaluation indicated that some compounds exhibited moderate cytotoxicity against HCT116, MCF7, HepG2 and A549 cancer cell lines in vitro, in which compound 36 was found to have best antiproliferative activity against the A549 cancer cell line with IC50 value of 5.4 μM. All compounds had low or no effect against L02 and HUVEC non-cancer cell lines. Compound 36 was further confirmed to mainly locate mitochondria in A549 cancer cells via laser-scanning confocal microscopy. Moreover, compound 36 was proved to increase ROS production and induce cell cycle arrest in S phase. Western blot analysis illustrated Bax/Bcl-2 ratio was increased at dose-dependent manner, and both cleaved caspase-3 and cleaved caspase-9 was enhanced by treated with compound 36. All the above evidences in vitro indicated that compound 36 might induce the apoptosis of A549 cancer cells via a mitochondria-dependent pathway.
- Lu, Yuanyuan,Wang, Linlin,Wang, Xiaobing,Xi, Tao,Liao, Jianmin,Wang, Zhixiang,Jiang, Feng
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p. 125 - 141
(2017/04/26)
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- Differential Targeting of Human Topoisomerase II Isoforms with Small Molecules
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(Chemical Equation Presented). The TOP2 poison etoposide has been implicated in the generation of secondary malignancies during cancer treatment. Structural similarities between TOP2 isoforms challenge the rational design of isoform-specific poisons to further delineate these processes. Herein, we describe the synthesis and biological evaluation of a focused library of etoposide analogues, with the identification of two novel small molecules exhibiting TOP2B-dependent toxicity. Our findings pave the way toward studying isoform-specific cellular processes by means of small molecule intervention.
- Mariani, Angelica,Bartoli, Alexandra,Atwal, Mandeep,Lee, Ka C.,Austin, Caroline A.,Rodriguez, Rapha?l
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supporting information
p. 4851 - 4856
(2015/06/25)
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- Copper catalyzed synthesis of 1-aryl-1,2,3-triazoles from aryl iodides, alkynes, and sodium azide
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Aryl azides were synthesized using heterogeneous porous Cu (0) catalyst via a coupling reaction of aryl iodides with sodium azide under mild conditions. Under the same conditions, one-pot Cu-catalyzed azide-alkyne cycloaddition of aryl iodides, alkynes, and sodium azide yielded 1-aryl-1,2,3-triazoles.
- Chen, Ying,Zhuo, Zi-Jian,Cui, Dong-Mei,Zhang, Chen
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p. 215 - 218
(2013/11/06)
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- Copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate)-catalyzed coupling of sodium azide with aryl iodides/boronic acids to aryl azides or aryl amines
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This work reports an efficient protocol for the coupling reaction of aryl iodides/boronic acids with sodium azide to aryl azides/amines in the presence of copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) Cu(TMHD)2 catalyst. The Cu(TMHD)2 catalyst is a structurally well-defined, O-containing, air- and moisture-stable, transition-metal complex and works at mild reaction conditions. It was observed that aryl azides can be reduced further to corresponding aniline derivatives using the same catalyst under basic reaction conditions for a prolonged period. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Lanke, Satish R.,Bhanage, Bhalchandra M.
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p. 399 - 407
(2014/01/06)
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- Introducing a new family of biotinylated Ir(III)-pyridyltriazole lumophores: Synthesis, photophysics, and preliminary study of avidin-binding properties
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Six new biotinylated reagents derived from monocationic pyridyl-1,2,3-triazole-based Ir(III) complexes of the general formula [(C∧N)2Ir(N∧N-spacer-X-CO-biotin)]+, where HC∧N is 2-phenylpyridine, N∧N is the neutral chelating (2-pyridyl)-1,2,3-triazole ligand, the term spacer refers to alkyl (-C11H22) or aromatic (p-phenyl- or 4,4′-biphenyl-) chains, and X is NH or O, have been prepared and characterized. Upon photoexcitation, all six complexes in fluid CH2Cl2 and aqueous solutions at room temperature displayed intense - with quantum yields as high as 0.60 (complex 4b) - and quite long-lived blue-green luminescence, corresponding in each case to a vibronically structured emission profile peaking at ca. 480 and ca. 508 nm. These features, in combination with the reduced rigidochromic shift that was observed from the same samples frozen at 77 K, suggested the 3LC-type excited states as the prevalent contributors to the emission. The interactions of these new biotinylated complexes with avidin have been studied by 4′-hydroxyazobenzene-2-carboxylic acid (HABA) assays and emission titrations. In general, the amplification of the emission intensity of the Ir(III) complexes occurring upon their interaction with avidin was observed. It is also worth mentioning how a similar or better response was displayed by [(C∧N)2Ir(N∧N-spacer-O-CO-biotin)]+-type complexes, in which biotin is appended to the Ir(III) lumophore through an ester moiety.
- Baschieri, Andrea,Muzzioli, Sara,Fiorini, Valentina,Matteucci, Elia,Massi, Massimiliano,Sambri, Letizia,Stagni, Stefano
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supporting information
p. 6154 - 6164
(2015/02/19)
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- A small molecule peptidomimetic that binds to c-KIT1 G-quadruplex and exhibits antiproliferative properties in cancer cells
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A modular synthesis of l-proline derived peptidomimetics has been developed using the CuI catalyzed Huisgen cycloaddition between an azido prolinamide with pyridine and benzene dicarboxamide containing dialkynes. F?rster Resonance Energy Transfer (FRET) melting assay provided an initial indication that the pyridyl analogue can stabilize the c-KIT1 quadruplex DNA. A competitive FRET-melting assay and Fluorescent Intercalator Displacement (FID) assay suggest that the pyridyl ligand shows excellent selectivity for c-KIT1 quadruplex over duplex DNA and other investigated G-quadruplexes. Molecular docking studies indicate that the pyridyl ligand can adopt unique conformations upon binding to c-KIT1 quadruplex due to the presence of intramolecular hydrogen bonds. The pyridyl ligand can perturb cell cycle progression and induce necrotic cell death of human hepatocellular liver carcinoma HepG2 cells.
- Chauhan, Ajay,Paladhi, Sushovan,Debnath, Manish,Mandal, Samir,Das, Rabindra Nath,Bhowmik, Sudipta,Dash, Jyotirmayee
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supporting information
p. 4422 - 4429
(2014/11/08)
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- DIHYDROPYRROLONES AND THEIR USE AS ANTIMICROBIAL AGENTS
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The present invention relates generally to antimicrobial dihydropyrrolone compounds, methods for their use and methods for preparing surfaces to which the dihydropyrrolone compounds are attached.
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Page/Page column 28
(2014/12/12)
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- Synthesis and biological evaluation of triazole-containing N-acyl homoserine lactones as quorum sensing modulators
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Many bacterial species are capable of assessing their local population densities through a cell-cell signaling mechanism termed quorum sensing (QS). This intercellular communication process is mediated by small molecule or peptide ligands and their cognate protein receptors. Numerous pathogens use QS to initiate virulence once they achieve a threshold cell number on a host. Consequently, approaches to intercept QS have attracted considerable attention as potential anti-infective therapies. Our interest in the development of small molecule tools to modulate QS pathways motivated us to evaluate triazole-containing analogs of natural N-acyl l-homoserine lactone (AHL) signals as non-native QS agonists and antagonists in Gram-negative bacteria. We synthesized 72 triazole derivatives of five broad structure types in high yields and purities using efficient Cu(i)-catalyzed azide-alkyne couplings. These compounds were evaluated for their ability to activate or inhibit two QS receptors from two prevalent pathogens-LasR from Pseudomonas aeruginosa and AbaR from Acinetobacter baumannii-using bacterial reporter strains. Several triazole derivatives were identified that were capable of strongly modulating the activity of LasR and AbaR. These compounds represent a new and synthetically accessible class of AHL analogs, and could find utility as chemical tools to study QS and its role in bacterial virulence.
- Stacy, Danielle M.,Le Quement, Sebastian T.,Hansen, Casper L.,Clausen, Janie W.,Tolker-Nielsen, Tim,Brummond, Jacob W.,Givskov, Michael,Nielsen, Thomas E.,Blackwell, Helen E.
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supporting information
p. 938 - 954
(2013/02/26)
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- HETEROCYCLIC UREA COMPOUNDS
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The present invention provides a compound of the following formula, racemates, enantiomers and salts thereof. Also provided is the use of these compounds as antibacterials, compositions comprising them and processes for their manufacture
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Page/Page column 63-64
(2013/07/05)
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- A simple and effective synthesis of aryl azides via arenediazonium tosylates
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Aromatic azides are formed in high yield from arenediazonium tosylates and sodium azide in water at room temperature or from aromatic amines via diazotization in the presence of p-TsOH Besides being experimentally simple, these methods do not require any metal catalysis and provide clean products without purification. Georg Thieme Verlag Stuttgart New York.
- Kutonova, Ksenia V.,Trusova, Marina E.,Postnikov, Pavels.,Filimonov, Victor D.,Parello, Joseph
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p. 2706 - 2710
(2013/10/21)
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- Multifunctional "click" prolinamides: A new platform for asymmetric aldol reactions in the presence of water with catalyst recycling
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"Click" chemistry is combined with organocatalysis to fabricate a multifunctional C3-symmetrical dendritic prolinamide with a hydrophobic aromatic core and hydrophilic triazolinium arms that exhibit high efficiency in catalyzing the asymmetric aldol reaction with cyclic ketones. The catalyst is water-compatible and remains active for five consecutive catalytic runs with a low catalyst loading (2 mol%), yielding the aldol products in high yields, diastereo- and enantioselectivities.
- Paladhi, Sushovan,Das, Joydeb,Mishra, Pratyush Kumar,Dash, Jyotirmayee
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supporting information
p. 274 - 280
(2013/05/08)
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- Fluorinated DF508-CFTR correctors and potentiators for PET imaging
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19F-modified bithiazole correctors and phenylglycine potentiators of the DF508-CFTR chloride channel were synthesized and their function assayed in cells expressing human DF508-CFTR and a halide-sensitive fluorescent protein. Fluorine was incorporated into each scaffold using prosthetic groups for future biodistribution imaging studies using positron emission tomography (PET). The DF508-CFTR corrector and potentiator potencies of the fluorinated analogs were comparable to or better than those of the original compounds.
- Davison, Holly R.,Solano, Danielle M.,Phuan, Puay-Wah,Verkman,Kurth, Mark J.
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scheme or table
p. 1602 - 1605
(2012/04/10)
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- Hydrogenation of azides over copper nanoparticle surface using ammonium formate in water
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Aryl azides undergo clean reduction by copper nanoparticles and ammonium formate in water. The surface hydrogen on copper nanoparticles is considered to be the active reducing species. A variety of functionalized aryl azides and aryl sulfonyl azides are reduced by this procedure to the corresponding amines with excellent chemoselectivity in high yields.
- Ahammed, Sabir,Saha, Amit,Ranu, Brindaban C.
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experimental part
p. 7235 - 7239
(2011/10/18)
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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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- Ditopic crown ether-guanidinium ion receptors for the molecular recognition of amino acids and small peptides
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A series of ditopic synthetic receptors based on a crown ether-guanidinium ion recognition motif is reported. The compounds show binding affinity to selected amino acids, including important neurotransmitters. The effect of the distance of the ammonium and the carboxylate ion, the rigidity of the spacer, and the use of pre-organized pyrrole- and pyrene-guanidinium groups on binding affinity and selectivity are discussed.
- Sp?th, Andreas,K?nig, Burkhard
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supporting information; experimental part
p. 1859 - 1873
(2010/04/06)
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- Rates of thermolysis of azidobenzenes in solution: Large stabilizations of transition states by charge transfer from electron-donor substituents
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Introduction of +R type para substituents into azidobenzenes causes very large increases in rate of thermolysis, up to 225-fold. The rates of nitrobenzene solutions at 120°C follow a Hammett-type linear free energy relationship log k = -5.44 - 2.33σ1 - 1.48R+ which indicates conjugative stabilization of a nitrene-like transition state. ortho-Substituents of the +R type causes still larger rate enhancements, up to 456-fold for 2-amino, which identify a special resonance proximity effect. It is suggested that the very high rates reported for such α-azidoheterocycles as 2-azidothiophene are due to similar resonance stabilizations and not to ring-opening concerted with nitrogen loss.
- Dyall, Leonard K.,L'abbe, Gerrit,Dehaen, Wim
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p. 971 - 975
(2007/10/03)
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- ELECTROCHEMICAL AZIDATION OF ANILINES
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It was found possible to effect the direct electrochemical introduction of the azido group into the aromatic nucleus of anilines and so obtain p-azidoanilines in high yields.
- Koshechko, V. G.,Shpil'nyi, S. A.,Pokhodenko, V. D.
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p. 328 - 331
(2007/10/02)
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