- Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes
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Nanotubes assembled from macrocyclic precursors offer a unique combination of low dimensionality, structural rigidity, and distinct interior and exterior microenvironments. Usually the weak stacking energies of macrocycles limit the length and mechanical
- Strauss, Michael J.,Asheghali, Darya,Evans, Austin M.,Li, Rebecca L.,Chavez, Anton D.,Sun, Chao,Becker, Matthew L.,Dichtel, William R.
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- Diverse Proton-Conducting Nanotubes via a Tandem Macrocyclization and Assembly Strategy
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Macrocycles that assemble into nanotubes exhibit emergent properties stemming from their low dimensionality, structural regularity, and distinct interior environments. We report a versatile strategy to synthesize diverse nanotube structures in a single, efficient reaction by using a conserved building block bearing a pyridine ring. Imine condensation of a 2,4,6-triphenylpyridine-based diamine with various aromatic dialdehydes yields chemically distinct pentagonal [5 + 5], hexagonal [3 + 3], and diamond-shaped [2 + 2] macrocycles depending on the substitution pattern of the aromatic dialdehyde monomer. Atomic force microscopy and in solvo X-ray diffraction demonstrate that protonation of the macrocycles under the mild conditions used for their synthesis drives assembly into high-aspect ratio nanotubes. Each of the pyridine-containing nanotube assemblies exhibited measurable proton conductivity by electrochemical impedance spectroscopy, with values as high as 10-3 S m-1 (90% R.H., 25 °C) that we attribute to differences in their internal pore sizes. This synthetic strategy represents a general method to access robust nanotube assemblies from a universal pyridine-containing monomer, which will enable systematic investigations of their emergent properties.
- Strauss, Michael J.,Jia, Manping,Evans, Austin M.,Castano, Ioannina,Li, Rebecca L.,Aguilar-Enriquez, Xavier,Roesner, Emily K.,Swartz, Jeremy L.,Chavez, Anton D.,Enciso, Alan E.,Stoddart, J. Fraser,Rolandi, Marco,Dichtel, William R.
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supporting information
p. 8145 - 8153
(2021/06/21)
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- Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
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Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
- K?nig, Burkhard,Wang, Hua,Wang, Shun
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p. 1653 - 1665
(2021/06/17)
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- Non-innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides
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We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated in situ. The combination of an isophthalonitrile photocatalyst and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.
- Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.,Williams, Oliver P.,Yeung, Charles S.
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supporting information
p. 10882 - 10889
(2021/07/31)
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- Purine compound obtained based on virtual docking as well as preparation method and application of same
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The invention provides a purine compound obtained based on virtual docking. The purine compound is screened in a virtual screening and pharmacophore manner, through a result of mutual evidence verification of virtual docking design and compound synthesis,
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Paragraph 0035-0042
(2020/11/26)
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- Visible Light-Induced Borylation of C-O, C-N, and C-X Bonds
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Boronic acids are centrally important functional motifs and synthetic precursors. Visible light-induced borylation may provide access to structurally diverse boronates, but a broadly efficient photocatalytic borylation method that can effect borylation of a wide range of substrates, including strong C-O bonds, remains elusive. Herein, we report a general, metal-free visible light-induced photocatalytic borylation platform that enables borylation of electron-rich derivatives of phenols and anilines, chloroarenes, as well as other haloarenes. The reaction exhibits excellent functional group tolerance, as demonstrated by the borylation of a range of structurally complex substrates. Remarkably, the reaction is catalyzed by phenothiazine, a simple organic photocatalyst with MW 200 that mediates the previously unachievable visible light-induced single electron reduction of phenol derivatives with reduction potentials as negative as approximately - 3 V versus SCE by a proton-coupled electron transfer mechanism. Mechanistic studies point to the crucial role of the photocatalyst-base interaction.
- Arman, Hadi D.,Dang, Hang. T.,Haug, Graham C.,He, Ru,Jin, Shengfei,Larionov, Oleg V.,Nguyen, Viet D.,Nguyen, Vu T.,Schanze, Kirk S.
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- Reductive Electrophotocatalysis: Merging Electricity and Light to Achieve Extreme Reduction Potentials
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We describe a new electrophotocatalytic strategy that harnesses the power of light and electricity to generate an excited radical anion with a reducing potential of -3.2 V vs SCE, which can be used to activate substrates with very high reduction potentials (Ered ≈ -1.9 to -2.9 V). The resultant aryl radicals can be engaged in various synthetically useful transformations to furnish arylboronate, arylstannane, and biaryl products.
- Kim, Hyunwoo,Kim, Hyungjun,Lambert, Tristan H.,Lin, Song
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supporting information
p. 2087 - 2092
(2020/02/04)
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- Copper-Photocatalyzed Borylation of Organic Halides under Batch and Continuous-Flow Conditions
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The copper-photocatalyzed borylation of aryl, heteroaryl, vinyl and alkyl halides (I and Br) was reported. The reaction proceeded using a new heteroleptic Cu complex under irradiation with blue LEDs, giving the corresponding boronic-acid esters in good to excellent yields. The reaction was extended to continuous-flow conditions to allow an easy scale-up. The mechanism of the reaction was studied and a mechanism based on a reductive quenching (CuI/CuI*/Cu0) was suggested.
- Nitelet, Antoine,Thevenet, Damien,Schiavi, Bruno,Hardouin, Christophe,Fournier, Jean,Tamion, Rodolphe,Pannecoucke, Xavier,Jubault, Philippe,Poisson, Thomas
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supporting information
p. 3262 - 3266
(2019/02/13)
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- Hydrogenation of (Hetero)aryl Boronate Esters with a Cyclic (Alkyl)(amino)carbene–Rhodium Complex: Direct Access to cis-Substituted Borylated Cycloalkanes and Saturated Heterocycles
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We herein report the hydrogenation of substituted aryl- and heteroaryl boronate esters for the selective synthesis of cis-substituted borylated cycloalkanes and saturated heterocycles. A cyclic (alkyl)(amino)carbene-ligated rhodium complex with two dimethyl groups at the ortho-alkyl scaffold of the carbene showed high reactivity in promoting the hydrogenation, thereby enabling the hydrogenation of (hetero)arenes with retention of the synthetically valuable boronate group. This process constitutes a clean, atom-economic, as well as chemo- and stereoselective route for the generation of cis-configured, diversely substituted borylated cycloalkanes and saturated heterocycles that are usually elusive and difficult to prepare.
- Ling, Liang,He, Yuan,Zhang, Xue,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 6554 - 6558
(2019/04/17)
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- Equilibration of Imine-Linked Polymers to Hexagonal Macrocycles Driven by Self-Assembly
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Macrocycles based on directional bonding and dynamic covalent bond exchange can be designed with specific pore shapes, sizes, and functionality. These systems retain many of the design criteria and desirable aspects of two-dimensional (2D) covalent organi
- Chavez, Anton D.,Evans, Austin M.,Flanders, Nathan C.,Bisbey, Ryan P.,Vitaku, Edon,Chen, Lin X.,Dichtel, William R.
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supporting information
p. 3989 - 3993
(2018/03/01)
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- The synthesis of a rigid conjugated viologen and its cucurbituril pseudorotaxanes
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A linear viologen (bis[4-(4-pyridinyl)phenyl] viologen, BPPV) characterized by a fully-conjugated structure was synthesized through Zinke reaction. BPPV consists of a unique linear sexiaryl structure and is apt to be encapsulated by cucurbit[n]uril (CB[n]
- Song, Yingfeng,Huang, Xinghua,Hua, Haojie,Wang, Qiaochun
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p. 229 - 235
(2016/11/09)
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- Nickel-Catalyzed Borylation of Aryl- and Benzyltrimethylammonium Salts via C-N Bond Cleavage
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By developing a mild Ni-catalyzed system, a method for direct borylation of sp2 and sp3 C-N bonds has been established. The key to this hightly efficient C-N bond borylative cleavage depends on the appropriate choice of the nickel catalyst Ni(COD)2, ICy·HCl as a ligand, and the use of 2-ethoxyethanol as the cosolvent. This transformation shows good functional group compatibility and can serve as a powerful synthetic tool for gram-scale synthesis and late-stage C-N borylation of complex compounds.
- Hu, Jiefeng,Sun, Heqing,Cai, Wangshui,Pu, Xinghui,Zhang, Yemin,Shi, Zhuangzhi
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- A novel protocol for the one-pot borylation/Suzuki reaction provides easy access to hinge-binding groups for kinase inhibitors
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The one-pot borylation/Suzuki reaction is a very efficient means of accessing cross-coupling products of two aryl-halide partners that generally requires the use of specific catalysts or ligands and/or relatively long reaction times. This new microwave-assisted method provides a quick one-pot borylation/Suzuki reaction protocol that we applied to the synthesis of various bi- or poly-aryl scaffolds, including a variety of aryl and heteroaryl ring systems and the core frameworks of kinase inhibitors vemurafenib and GDC-0879.
- Hooper,Zambon,Springer
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supporting information
p. 963 - 969
(2016/01/15)
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- Amphiphilic inclusion spaces for various guests and regulation of fluorescence intensity of 1,8-bis(4-aminophenyl)anthracene crystals
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A host framework for inclusion of various guest molecules was investigated by preparation of inclusion crystals of 1,8-bis(4-aminophenyl)anthracene (1,8-BAPA) with organic solvents. X-ray crystallographic analysis revealed construction of the same inclusion space incorporating 1,8-BAPA and eight guest molecules including both non-polar (benzene) and polar guests (N,N-dimethylformamide, DMF). Fluorescence efficiencies varied depending on guest molecule polarity; DMF inclusion crystals exhibited the highest fluorescence intensity (ΦF=0.40), four times as high as that of a benzene inclusion crystal (ΦF=0.10). According to systematic investigations of inclusion phenomena, strong host-guest interactions and filling of the inclusion space led to a high fluorescence intensity. Temperature-dependent fluorescence spectral measurements revealed these factors effectively immobilised the host framework. Although hydrogen bonding commonly decreases fluorescence intensity, the present study demonstrated that such strong interactions provide excellent conditions for fluorescence enhancement. Thus, this remarkable behaviour has potential application toward sensing of highly polar molecules, such as biogenic compounds. Immobilisation by guests from within: Inclusion crystals of 1,8-bis(4-aminophenyl)anthracene (1,8-BAPA) constructed the same inclusion space for eight guest molecules including not only non-polar guests (benzene) but also polar guests (DMF; see scheme). Fluorescence efficiencies varied depending on guest molecule polarity. Strong host-guest interactions and filling of the inclusion space led to a high fluorescence intensity.
- Sugino, Misa,Hatanaka, Keisuke,Araki, Yusuke,Hisaki, Ichiro,Miyata, Mikiji,Tohnai, Norimitsu
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p. 3069 - 3076
(2014/03/21)
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- Iron catalysis and water: A synergy for refunctionalization of boron
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A new catalytic system has been optimized to promote the conversion of boron species into others. FeCl3 associated with imidazole and water favors boron refunctionalization under mild conditions. Georg Thieme Verlag Stuttgart New York.
- Wood, John L.,Marciasini, Ludovic D.,Vaultier, Michel,Pucheault, Mathieu
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supporting information
p. 551 - 555
(2014/03/21)
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- Synthesis of macrocycles containing 1,3,4-oxadiazole and pyridine moieties
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A series of peptide-like 25-28 membered macrocycles containing 1,3,4-oxadiazoles and pyridines bearing a chiral center scaffold have been synthesized by using known coupling reagents and common protecting groups. The yield of the purified macrocycles was poor on an average, yet it seems to be independent of amino acid substitution or stereochemistry. These macrocycles represent a new class of structures for further development and for future application in high-throughput screening against a variety of biological targets.
- Poojari, Subba,Naik, Parameshwar,Krishnamurthy
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p. 305 - 309
(2014/01/06)
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- Identification of pyrazine-based TrkA inhibitors: Design, synthesis, evaluation, and computational modeling studies
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Trk receptors play a key role in the development and maintenance of neuronal networks. Recent evidence suggests that the Trk family, specifically TrkA, is an important driver for tumour growth, inflammatory and neuropathic pain, and chemoresistance. Through a computational screen, a novel Trk active pharmacophore was identified and a series of pyrazine-based inhibitors were developed, which potently inhibited TrkA. Inhibitors displayed the highest activity on TrkA when screened against a small, tyrosine kinase panel and also exhibited a non-linear SAR. Predicted binding modes of the inhibitors were examined, which identified exploitable regions for future development of more advanced inhibitors. This journal is
- Frett, Brendan,McConnell, Nick,Wang, Yuanxiang,Xu, Zhigang,Ambrose, Andrew,Li, Hong-Yu
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p. 1507 - 1514
(2014/12/12)
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- Ligand-assisted J-type aggregates of zinc porphyrin: Anticooperative molecular organization in self-assembled bolaamphiphile
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Bolaamphiphilic zinc porphyrins bearing a 2-pyridylethynyl or 4-methoxyphenylethynyl group, Zn(PyPor) or Zn(ArPor), respectively, were newly synthesized in order to explore the molecular organizing behaviours within the interior hydrophobic layer of aqueous self-assemblies. Well-ordered J-type aggregates of Zn(PyPor) were formed in aqueous self-assembled bolaamphiphile, whereas J-type aggregates of Zn(ArPor) were disordered. The titration experiments suggest that axial coordination bond improves the structural uniformity of the J-type aggregates of Zn(PyPor). In a homogeneous isotropic media, on the other hand, Zn(PyPor) formed an antiparallel dimer through self-complementary coordination. Unprecedented molecular organization of ligand-assisted J-type aggregates is described in the term of anticooperative effect under the bulk conditions. The Royal Society of Chemistry 2010.
- Morisue, Mitsuhiko,Morita, Takefumi,Kuroda, Yasuhisa
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experimental part
p. 3457 - 3463
(2010/08/21)
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- Pyrazolopyrimidines as therapeutic agents
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The present invention is directed to pyrazolopyrimidine derivatives of formula (I) wherein the substituents are defined herein, which are useful as kinase inhibitors and as such are useful for affecting angiogenesis and diseases and conditions associated with angiogenesis.
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- Pyrazolopyrimidines as therapeutic agents
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The present invention provides compounds of Formula I, including pharmaceutically acceptable salts and/or prodrugs thereof, where G, R2, and R3 are defined as described herein.
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