- Synthesis of side-chain functional polyesters via Baylis-Hillman polymerization
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Strategies that allow access to side-chain functional polyesters are valuable as they would enable to engineer the properties of these hydrolytically degradable materials. This contribution explores the feasibility of a novel approach toward side-chain functional polyesters that is based on the Baylis-Hillman reaction, which involves the base-catalyzed condensation of an aldehyde and an acrylate building block to produce an α-methylene-β- hydroxycarbonyl compound. Using 1,3-butanediol acrylate and 2,6- pyridinecarboxaldehyde as monomers and DABCO as catalyst, polymers with a degree of polymerization of up to 25 could be prepared. These polymers are attractive as they contain chemically orthogonal side-chain hydroxyl and vinyl groups that can be further modified. In the first experiments, it was demonstrated that the side-chain hydroxyl and vinyl groups can be quantitatively postmodified with phenyl isocyanate and methyl-3-mercaptopropionate, respectively. As the Baylis-Hillman polymerization does not require the use of side-chain protected monomers, this route may represent an interesting alternative strategy for the preparation of side-chain functional polyesters.
- Ji, Sanhao,Bruchmann, Bernd,Klok, Harm-Anton
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- Synthesis and crystal structure of metal complexes based on 2,6-bis(6-methylquinolin-2-yl)pyridine ligand
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Two mononuclear five-coordinated transition metal complexes FeLCl 2 (I) and MnLCl2 (II) containing tridentate 2,6-bis(6-methylquinolin-2-yl)pyridine ligand (L) have been synthesized and characterized by single-crystal X-ray crystallography. In the complexes, the metal center was tridentately chelated by ligand and further coordinated by two chlorine atoms, resulting in distorted trigonal-bipyramidal geometry for complex I and II, respectively. In addition, crystal packing in complex is stabilized by C-H...Cl intermolecular hydrogen bond, which link the mononuclear complex to the 1D chain.
- Li,Li,Zhang,Wang,Zhang,Zhao
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- Synthesis and Coordinating Properties of a Ferrocenophane containing a Pyridine Unit
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The cryptand 3, containing both a ferrocene unit and a 2,6-disubstituted pyridine unit, forms complexes with di- and tri-valent cations; the X-ray crystal structure of a 2:1 (host:guest) complex with Ca2+ shows that the metal cations are coordinated by a cis-configuration of the carbonyl groups on the short (pyridyl) side of the macrocyclic ring, which confirms the interpretation of the 1H and 13C NMR data of the complexes in solution.
- Hall, C. Dennis,Tucker, James H. R.,Chu, Sunny Y. F.,Parkins, Adrian W.,Nyburg, Stanley C.
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- Cation and anion fluorescent and electrochemical sensors derived from 4,4′-substituted biphenyl
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Five new fluorescent macrocyclic ligands derived from biphenyl are described. These new compounds can be used in cation and anion recognition and sensing. Their fluorescent and electrochemical properties are studied and the influence of the biphenyl conformation on these properties is considered. The X-ray single crystal structure of one of the described ligands has been determined.
- Costero, Ana M.,Ba?uls, M. José,Aurell, M. José,Ochando, Luis E.,Doménech, Antonio
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- Lanthanide(III) and yttrium(III) coordination compounds of diastereomeric (2+2) macrocyclic imines derived from 2,6-diformylpyridine and trans-1,2-diaminocyclopentane
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The enantiopure mononuclear coordination compounds [Ln(L1)]Cl3·nH2O (Ln = Y(III), Nd(III), Sm(III), Eu(III), Tb(III), Yb(III)) of the chiral macrocyclic (2+2) imine L1 (L1RRRR and L1SSSS), derived from (1R,2R) and (1S,2S)-1,2-diaminocyclopentane (DACP) and 2,6-diformylpyridine (DFP), have been synthesized in the templated condensation of the precursors in the presence of the appropriate metal salts. From the racemic trans-DACP and DFP in the templated condensation, a series of racemic mononuclear coordination compounds [Ln(L1rac)]Cl3·nH2O (Ln = Y(III), Nd(III), Sm(III), Eu(III), Tb(III), Yb(III)) have been obtained. In the absence of metal salt, the condensation of the achiral precursors leads to a meso type Schiff base L2, which in the presence of lanthanide(III) salts produced the mononuclear coordination compounds [Ln(L2)]Cl3·nH2O (Ln = Y(III), Nd(III), Sm(III), Eu(III), Tb(III)). The mononuclear coordination compounds with the L1 and L2 ligands have been characterised by NMR spectroscopy, mass spectrometry, elemental analyses and/or circular dichroism (CD). 1H NMR signals of CDCl3/CD3OD solutions of the Y(III), Nd(III), Sm(III) and Eu(III) coordination compounds have been assigned on the basis of their COSY and HMQC spectra, and for the remaining lanthanide coordination compounds (Tb(III) and Yb(III)) the signals were tentatively assigned on the basis of linewidths analyses. The properties and stability of the lanthanide(III) and yttrium(II) coordination compounds of the racemic macrocycle L1rac have been compared with those of the isomeric meso type macrocycle L2 in organic solvents and water. Axial ligand exchange for several coordination compounds was investigated by 1H NMR titration experiments in organic solvents. The X-ray crystal structures of the representative mononuclear coordination compounds [Nd(L1RRRR)Cl(H2O)2]Cl2·0.5MeOH·H2O, [Nd(L1rac)Cl(H2O)2]Cl2·1.6MeOH·0.2H2O, [Y(L1rac)Cl(H2O)2]Cl2·3.5H2O, [Y(L1rac)Cl(H2O)2][Y(L1rac)(H2O)3]Cl5·6.8H2O and [Nd(L2)Cl2(H2O)]Cl with the diastereomeric ligands L1 and L2 have been determined.
- Gregoliński, Janusz,?lepokura, Katarzyna
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- Functional, hyperbranched polyesters via Baylis-Hillman polymerization
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Hyperbranched polyesters are among the most common hyperbranched polymers. One of the interesting features of hyperbranched polyesters is that they contain unreacted hydroxyl and carboxylic acid groups at the linear and terminal structural units, which can be postmodified to adjust thermal, solubility, or mechanical properties, or to prepare core-shell type architectures. This article reports on the synthesis of a novel class of hyperbranched polyesters via an A2 + B3 type Baylis-Hillman polymerization of 2,6-pyridinedicarboxaldehyde and trimethylolpropane triacrylate. Baylis-Hillman polymerization generates highly functional polyesters that contain not only unreacted aldehyde and/or acrylate groups at the linear and terminal structural units but also chemically orthogonal vinyl and hydroxyl groups along the polymer backbone. Using 3-hydroxyquinuclidine as the catalyst, hyperbranched polymers with number-average molecular weights up to 7500 g/mol and degrees of branching up to 0.81 were obtained. To demonstrate the versatility of these hyperbranched polyesters to act as platforms for further derivatization, the orthogonal postpolymerization modification of the hydroxyl, vinyl, and pyridine functional moieties with phenyl isocyanate, methyl-3-mercaptopropionate, and methyl iodide is presented.
- Ji, Sanhao,Bruchmann, Bernd,Wurm, Frederik,Klok, Harm-Anton
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- Synthesis, characterization, X-ray structure and photoluminescence properties of two Ce(III) complexes derived from pentadentate ligands
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In this study, two new Ce(III) complexes [Ce(L1)(NO3)3]·H2O and [Ce(L2)(NO3)3]·H2O were synthesized and characterized by spectroscopic and analytical methods where L1 and L2 are pentadentate diimine ligands. Molecular structure of [Ce(L1)(NO3)3]·H2O was determined by single crystal X-ray diffraction study. The complex was found to crystallize as [Ce(L1)(NO3)3] H2O. In the complex, the ligand L1 coordinates to the Ce(III) ion with the N3O2 donor set and the Ce(III) ion sits within the cavity of acyclic ligand. The Ce(III) ion is 11-coordinated by three nitrogen atoms from the ligand and eight O atoms, six of which come from three nitrate ions, two from the ligand. In the structure of the complex, water molecules link molecules together to form a 3D hydrogen bond network. Thermal behavior of the Schiff base ligands and their Ce(III) complexes metal complexes were studied under nitrogen atmosphere in the temperature range of 20-800 °C. Thermal stability of the ligands increased upon complexation with Ce(III) ion. In the UV-Vis spectra of Ce(III) complexes, new absorption bands appeared at 340-450 nm and these new bands were attributed to metal-ligand (M-L) charge transitions. Photoluminescence properties of the ligands and their Ce(III) complexes were examined.
- K?se, Muhammet,Akgün, Eyup,Ceyhan, G?khan
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- Chiral superstructures from homochiral Zn2+, Co2+, Fe2+-2,6-bis (aryl ethylimine)pyridine complexes
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We report the hierarchical supramolecular organization of metallosupramolecular homochiral complexes 1-Λ-(S,S,S,S)-M2+/1-?-(R,R,R,R)-M2+ and 2- Λ-(S,S,S,S)-M2+/2-?- (R,R,R,R)-M2+ of M2+ = Co2+, Fe2+, Zn2+ metal ions with chiral pseudo-terpyridine-type ligands: 1-(S,S) or 1-(R,R) = 2,6-bis (naphthyl ethylimine)pyridine and 2-(S,S) or 2-(R,R) = 2,6-bis (phenyl-ethylimine)pyridine. Circular dichroism measurements in solution were used to confirm the enantiomeric nature of all twelve complexes. For crystal structures of 1- Λ- (S,S,S,S)-M2+ or 1-?- (R,R,R,R)-M2+ complexes, absolute configurations {? (or P), Λ (or M)} were confirmed by refinement of the Flack parameter x: ?0.007 ≤ x ≤ 0.11 for the single crystals of 1-Λ-(S,S,S,S)-M2+/1-?- (R,R,R,R)-M2+, 2- Λ- (S,S,S,S)-Fe2+, and 2-?- (R,R,R,R)-Co2+.
- Dumitru, Florina,van der Lee, Arie,Barboiu, Mihail
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- A novel rhodamine-based optical probe for mercury(II) ion in aqueous medium: A nanomolar detection, wide pH range and real water sample application
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In present work, we designed and synthesized new chemosensor RPy, containing the rhodamine and 2,6-pyridinedicarboxaldehyde functionality, for the selective detection of mercury (II) (Hg2+) ion in aqueous DMSO solvents. The RPy acts as “turn ON” probe for Hg2+ ion with high selectivity and sensitivity over the series of other competing metal ions based on colorimetric and fluorimetric techniques. Due to the incorporation of two rhodamine moieties enhance the chelation sites for mercury binding, which reflects in the lowering of the detection limit up to 26 nM. The Job plot method confirms the 1:2 stoichiometric interactions between the RPy and Hg2+ ion. The formation of the chelation complex between RPy and Hg2+ ion with spirolactam ring opening was thoroughly investigated by absorption, emission, 1H NMR, and mass analysis. The detection of Hg2+ ion by RPy is retained at broad pH range 4–9. Further, the probe RPy is successfully explored to measure the contamination of Hg2+ ion in the real water samples using spike and recovery method.
- Patil, Sagar K.,Das, Dipanwita
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- Synthesis, Characterization and Properties of Expanded Pyriporphyrins: A New Family of Alkylidenyl Porphyrin Homologues Bearing meso-Exocyclic Double Bonds
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We present the synthesis and characterization of a new family of expanded meso-alkylidenyl (2,6-pyri)porphyrinoids bearing multiple exocyclic double bonds at the meso-positions. The synthesis was accomplished by using mixed pyrrole condensation. Similar to meso-alkylidenyl porphyrinoids, this study revealed that pyriporphyrinoids do not possess a porphyrin-like, global-aromatic character. The synthesized 2,6-pyripentaphyrin 1 displays selective ratiometric sensing of pyrophosphate anion in organic solvent.
- Abebayehu, Abeje,Dutta, Ranjan,Lee, Chang-Hee
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- Metal organic complex with near-infrared absorption and emission properties and preparation method thereof
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The invention discloses a metal organic complex with near-infrared absorption and emission properties and a preparation method thereof. The metal organic complex is prepared by the following steps of:carrying out condensation reaction on an aldehyde group-containing ligand precursor and thiophene or furan or pyrrole or benzene ring or selenophen to obtain a ligand, and carrying out coordination reaction on the ligand and Pd(DMSO)2Cl2 or Pt(DMSO)2Cl2 to obtain a complex monomer, and carrying out condensation dimerization reaction on the complex monomer to obtain the metal organic complex. Themetal organic complex with near-infrared absorption and emission properties has near-infrared absorption and emission properties, and can be used as a wave-absorbing material in the fields of near-infrared imaging, invisible ink and anti-counterfeiting printing, near-infrared bar code invisible identification, plasma display panels, dye-sensitized solar cells, near-infrared light emitting diodes and the like.
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- Design, synthesis, and biological characterization of a new class of symmetrical polyamine-based small molecule CXCR4 antagonists
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CXCR4, a well-studied coreceptor of human immunodeficiency virus type 1 (HIV-1) entry, recognizes its cognate ligand SDF-1α (also named CXCL12) which plays many important roles, including regulating immune cells, controlling hematopoietic stem cells, and directing cancer cells migration. These pleiotropic roles make CXCR4 an attractive target to mitigate human disorders. Here a new class of symmetrical polyamines was designed and synthesized as potential small molecule CXCR4 antagonists. Among them, a representative compound 21 (namely HF50731) showed strong CXCR4 binding affinity (mean IC50 = 19.8 nM) in the CXCR4 competitive binding assay. Furthermore, compound 21 significantly inhibited SDF-1α-induced calcium mobilization and cell migration, and blocked HIV-1 infection via antagonizing CXCR4 coreceptor function. The structure-activity relationship analysis, site-directed mutagenesis, and molecular docking were conducted to further elucidate the binding mode of compound 21, suggesting that compound 21 could primarily occupy the minor subpocket of CXCR4 and partially bind in the major subpocket by interacting with residues W94, D97, D171, and E288. Our studies provide not only new insights for the fragment-based design of small molecule CXCR4 antagonists for clinical applications, but also a new and effective molecular probe for CXCR4-targeting biological studies.
- An, Jing,Fang, Xiong,Huang, Lina S.,Huang, Ziwei,Liang, Boqiang,Meng, Qian,Schooley, Robert T.,Wang, Juan,Xu, Yan,Zhang, Chaozai,Zhang, Huijun,Zhang, Xingquan,Zhu, Siyu
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- Manganese Complex of a Rigidified 15-Membered Macrocycle: A Comprehensive Study
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Owing to the increasing importance of manganese(II) complexes in the field of magnetic resonance imaging (MRI), large efforts have been devoted to find an appropriate ligand for Mn(II) ion encapsulation by providing balance between the seemingly contradictory requirements (i.e., thermodynamic stability and kinetic inertness vs low ligand denticity enabling water molecule(s) to be coordinated in its metal center). Among these ligands, a large number of pyridine or pyridol based open-chain and macrocyclic chelators have been investigated so far. As a next step in the development of these chelators, 15-pyN3O2Ph and its transition metal complexes were synthesized and characterized using established methods. The 15-pyN3O2Ph ligand incorporates both pyridine and ortho-phenylene units to decrease ligand flexibility. The thermodynamic properties, protonation and stability constants, were determined using pH-potentiometry; the solid-state structures of two protonation states of the free ligand and its manganese complex were obtained by single crystal X-ray diffractometry. The results show a seven-coordinate metal center with two water molecules in the first coordination sphere. The longitudinal relaxivity of [Mn(15-pyN3O2Ph)]2+ was found to be 5.16 mM-1 s-1 at 0.49 T (298 K). Furthermore, the r2p value of 11.72 mM-1 s-1 (0.49 T), which is doubled at 1.41 T field, suggests that design of this Mn(II) complex does achieve some characteristics required for contrast imaging. In addition, 17O NMR measurements were performed in order to access the microscopic parameters governing this key feature (e.g., water exchange rate). Finally, manganese complexes of ligands with analogous polyaza macrocyclic scaffold have been investigated as low molecular weight Mn(CAT) mimics. Here, we report the H2O2 disproportionation study of [Mn(15-pyN3O2Ph)]2+ to demonstrate the versatility of this ligand scaffold as well.
- Freire, David M.,Green, Kayla N.,Kálmán, Ferenc Krisztián,Molnár, Enik?,Pota, Kristof,Tircsó, Gyula
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supporting information
(2020/08/12)
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- Efficient Pincer-Ruthenium Catalysts for Kharasch Addition of Carbon Tetrachloride to Styrene
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A series of NNN pincer-ruthenium complexes (R2NNN)RuCl2(PPh3) (R=Cyclohexyl (Cy), t-butyl (tBu), i-propyl (iPr) and phenyl (Ph)) have been synthesized and characterized. These pincer-ruthenium complexes have been used to catalyse the Kharasch addition or atom transfer radical addition (ATRA) of carbon tetrachloride to styrene. Among the pincer-ruthenium catalysts screened for the Kharasch addition, the catalytic activity followed the order (Cy2NNN)RuCl2(PPh3)>(iPr2NNN)RuCl2(PPh3)?(Ph2NNN)RuCl2(PPh3). The oxidation of Ru(II) is easier with (Cy2NNN)RuCl2(PPh3) and (iPr2NNN)RuCl2(PPh3) in comparison with (Formula presented.) RuCl2(PPh3) as indicated by cyclic voltammetry studies. The catalyst precursor (R2NNN)RuCl2(PPh3) itself is the resting state of the reaction. The rate determining step involves the generation of the five-coordinate 16-electron ruthenium(II) species (R2NNN)RuCl2. Owing to weaker binding of triphenyl phosphine to ruthenium, the generation of catalytically active 16-electron species (Cy2NNN)RuCl2 and (iPr2NNN)RuCl2 are more favourable. The complex (Cy2NNN)RuCl2(PPh3) demonstrates very high productivity (5670 turnovers after 48 h at 140 °C) in the absence of any co-catalyst radical initiator. To the best of our knowledge, our turnovers (ca. 5670) are much higher than that reported hitherto. Quantum mechanical calculations demonstrate that the path involving the activation of carbon tetrachloride by (Cy2NNN)RuCl2 is more favoured than the path where carbon tetrachloride is activated by (Cy2NNN)RuCl2(η2-styrene). Density functional theory (DFT) and kinetic studies are in accord with the widely accepted mechanism involving the single electron transfer (SET) from ruthenium(II) to chloride radical with concomitant generation of a benzyl radical which is trapped by the resulting ruthenium(III) species. (Figure presented.).
- Das, Kanu,Dutta, Moumita,Das, Babulal,Srivastava, Hemant Kumar,Kumar, Akshai
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p. 2965 - 2980
(2019/04/30)
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- A Design Strategy for Single-Stranded Helicates using Pyridine-Hydrazone Ligands and PbII
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The reactions of py-hz ligands (L1–L5) with Pb(CF3SO3)2?H2O resulted in some rare examples of discrete single-stranded helical PbII complexes. L1 and L2 formed non-helical mononuclear complexes [PbL1(CF3SO3)2]?CHCl3 and PbL2(CF3SO3)2][PbL2CF3SO3]CF3SO3?CH3CN, which reflected the high coordination number and effective saturation of PbII by the ligands. The reaction of L3 with PbII resulted in a dinuclear meso-helicate [Pb2L3(CF3SO3)2Br]CF3SO3?CH3CN with a stereochemically-active lone pair on PbII. L4 directed single-stranded helicates with PbII, including [Pb2L4(CF3SO3)3]CF3SO3?CH3CN and [Pb2L4CF3SO3(CH3OH)2](CF3SO3)3?2 CH3OH?2 H2O. The acryloyl-modified py-hz ligand L5 formed helical and non-helical complexes with PbII, including a trinuclear PbII complex [Pb3L5(CF3SO3)5]CF3SO3?3CH3CN?Et2O. The high denticity of the long-stranded py-hz ligands L4 and L5 was essential to the formation of single-stranded helicates with PbII.
- Lobo, Maureen J.,Moratti, Stephen C.,Hanton, Lyall R.
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p. 1184 - 1193
(2019/01/16)
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- Novel imine-linked covalent organic frameworks: Preparation, characterization and application
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Covalent organic frameworks (COFs) have attracted considerable interest over the past few years, but the available type of monomers is still limited. Herein, two novel imine-linked COFs (TaDAP and TaDA) were constructed by the condensation of 1,3,5-tris-(4-aminophenyl) triazine with 2,6-diformylpyridine (forming TaDAP) and 1,3-benzenedialdehyde (forming TaDA) under solvothermal conditions. The structures of the COFs were confirmed and characterized by solid state 13C NMR, FT-IR, PXRD, TGA, SEM, TEM and nitrogen sorption isotherms. They appear as regular spherical particles and possess excellent thermal stability. It was also found that their dispersions emit strong fluorescence, and display quick response to certain metal ions. In particular, TaDAP can detect Fe3+ with sensitivity and selectivity. Moreover, both the COFs present excellent catalytic activity towards the Knoevenagel reaction. Accordingly, this study not only provides a new way to enrich the family of COFs, but also develops their potential applications in metal ion detection.
- Wu, Xingchun,Wang, Bowei,Yang, Ziqi,Chen, Ligong
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supporting information
p. 5650 - 5655
(2019/03/13)
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- Cobalt imine–pyridine–carbonyl complex functionalized metal–organic frameworks as catalysts for alkene epoxidation
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Aerobic epoxidation of alkene is a green and economical route to produce epoxides. For such reaction, transition metal complexes exhibit favorable catalytic activity. In this work, NH2-MIL-101, a stable metal–organic framework (MOF) material with large surface area and high pore volume, was functionalized with pyridine-2,6-dicarbaldehyde and Co(NO3)2, to realize the immobilization of Co(II) via imine–pyridine–carbonyl (N,N,O) tridentate ligands bonding to MOF skeleton. The modified materials were applied as heterogeneous catalysts for the aerobic epoxidation of cyclohexene at ambient temperature, and multiple factors were studied to explore their influences on catalytic effects. Under the optimal reaction conditions, satisfactory substrate conversion and epoxide selectivity were reached. In addition, this catalytic system is suitable for a variety of alkene substrates. Furthermore, recycle experiments and infrared spectroscopy characterization illustrated that the coordination surroundings of Co are altering smoothly during the reaction process, thus having?an impact on the performance of catalyst.
- Qin, Yutian,Wang, Bowei,Li, Jiayi,Wu, Xingchun,Chen, Ligong
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p. 595 - 602
(2019/05/04)
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- Dinuclear Manganese(II), Cobalt(II), and Nickel(II) Aryl Phosphates Incorporating 4′-Chloro-2,2′:6′,2′′-Terpyridine Coligands – Efficient Catalysts for Alcohol Oxidation
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The dinuclear cyclo(metallo)phosphates [M(dipp)(Cl-terpy)]2 [M = Mn (1), Ni (2)] and the mononuclear cobalt phosphate [Co(dippH)(Cl-terpy)(MeOH)(H2O)]·dippH (3) were synthesized through the reactions of 4′-chloro-2,2′:6′,2′′-terpyridine (Cl-terpy) and 2,6-diisopropylphenyl phosphate (dippH2) with manganese, nickel, and cobalt acetates. The formation of 1–3 is supported by spectroscopic, thermogravimetric, and microanalytical data. The molecular structures of 1 and 3 were confirmed by single-crystal X-ray diffraction studies. Compounds 1 and 2 are dimeric and feature two octahedral metal centers bridged by dianionic dipp ligands. On the other hand, 3 exists as a monomer in the solid state, but dissolution in methanol converts it to a dimeric form similar to those of 1 and 2, as evidenced by ESI-MS studies. Compounds 1–3 were employed as catalysts for alcohol oxidation reactions with tert-butyl hydroperoxide (TBHP) as the oxidant. The manganese phosphate 1 exhibits better catalytic activity in terms of selectivity and substrate conversion compared with those of 2 and 3 under similar conditions.
- Bhat, Gulzar A.,Rajendran, Antony,Murugavel, Ramaswamy
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p. 795 - 804
(2018/02/21)
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- GUANIDINE COMPOUNDS FOR REMOVAL OF OXYANIONS FROM AQUEOUS SOLUTIONS AND FOR CARBON DIOXIDE CAPTURE
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Methods for removing oxyanions from water according to the following steps: (i) dissolving an oxyanion precipitating compound into the aqueous source to result in precipitation of an oxyanion salt of the oxyanion precipitating compound; and (ii) removing the oxyanion salt from the water containing the oxyanion to result in water substantially reduced in concentration of the oxyanion; wherein the oxyanion precipitating compound has the following composition: wherein A is a ring-containing moiety and Xm? is an anionic species with a magnitude of charge m. The invention employs bis-iminoguanidinium compounds according to Formula (1a) as well as neutral precursor compounds according to Formula (1), which can be used for removing undesirable species from aqueous solutions or air, such as removal of sulfate from water and carbon dioxide from air.
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Paragraph 0055
(2018/05/26)
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- Synthesis method of novel complex for drug testing
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The invention relates to a synthesis method of a novel complex for drug testing, in particular to a Pb-containing complex Pb(bpbp)3(NO3)2, wherein bpbp represents 2,6-bis(2-(1-phenyl)benzimidazole)pyridine. The invention further relates to a crystal structure of the complex. The preparation method is simple and fast, and the complex is low in toxicity and high in yield. Compared with a conventional crystal culture method of the ligand complexes, the method has the advantages that solvents for synthesis are water and methanol, and a large quantity of crystals can be obtained in three days. Withadoption of a fluorescence analysis method, a fluorescence spectrum of interaction of a target product and BSA (bovine serum albumin) is tested; the fluorescence quenching phenomenon of BSA indicatesthat the complex has stronger interaction with BSA, so that the complex can be applied to biological drug detection.
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Paragraph 0027; 0039; 0043
(2018/05/16)
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- Polydentate 4-Pyridyl-terpyridine Containing Discrete Cobalt Phosphonate and Polymeric Cobalt Phosphate as Catalysts for Alcohol Oxidation
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Mononuclear discrete cobalt phosphonate [Co(pytpy)(tBuPO3H)2(H2O)]·H2O (1) and 1D zigzag polymeric cobalt phosphate [Co(pytpy)2(dipp)(MeOH)·2MeOH]n (2) were prepared from the reactions of tert-butyl phosphonic acid (tBuPO3H2) and organic-soluble 2,6-diisopropylphenyl phosphate (dippH2) ligands with Co(OAc)2·4H2O in the presence of 4′-pyridyl 2,2′:6′,2′′-terpyridine in MeOH/CHCl3(1:1 v/v) solvent mixture at 25 °C. The new compounds were characterized by analytical, thermo-analytical, and spectroscopic techniques. Further, the molecular structures were established by single-crystal X-ray diffraction studies. Mass spectrometry analysis reveal that both the compounds exist in the solution phase as dimers. Compound 1 was employed as homogeneous catalysts for alcohol oxidation reactions using tert-butyl hydroperoxide (TBHP) as the oxidant.
- Bhat, Gulzar A.,Rajendran, Antony,Murugavel, Ramaswamy
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p. 692 - 699
(2018/08/06)
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- A 2, 6 - di (2 - (1 - phenyl) benzimidazole) pyridine preparation method (by machine translation)
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The invention relates to a 2, 6 - di (2 - (1 - phenyl) benzimidazole) pyridine of the preparation method, adopt the one-step reduction guan Huanfa synthesis: the 2 - nitro diphenylamine, 2, 6 - pyridine-phthalaldehyde, reducing agent, solvent and the like according to appropriate ratio after being mixed 100 °C reflow conditions 24h can be, to overcome the traditional benzimidazole compound of preparation requires high temperature or microwave condition and the protection of inert gas atmosphere for a long time under the defect of the reaction. In addition, the invention adopts the preparation method does not need to carry out the drying treatment of the solvent, also does not need to nitrogen or argon and other inert gas protection, reduces energy consumption; and the product after treatment is simple, conversion is relatively high, the resulting yield of a target product can be up to 47%, and the invention uses the apparatus is relatively simple, wide sources of raw materials, the cost is low, the invention has obvious economic and environmental benefit. (by machine translation)
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Paragraph 0043-0046
(2017/08/25)
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- Acceptorless dehydrogenation of alcohols on a diruthenium(II,II) platform
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The diruthenium(II,II) complex [Ru2(L1)(OAc)3]Cl (1), spanned by a naphthyridine-diimine ligand and bridged by three acetates, has been synthesized. The catalytic efficacy of complex 1 has been evaluated for the acceptorless dehydrogenation (AD) of alcohols and for the dehydrogenative coupling reactions of alcohols with Wittig reagents. The diruthenium(II,II) complex is an excellent catalyst for AD of a diverse range of alcohols, and it is shown to be particularly effective for the conversion of primary alcohols to the corresponding aldehydes without undesired side products such as esters. Triphenylphosphonium ylides in a one-pot reaction with alcohols afforded the corresponding olefins in high yields with excellent E selectivity. The liberated dihydrogen gas was identified and measured to be 1 equiv with respect to alcohol. Deuteration studies with PhCD2OH revealed the absence of isotope scrambling in the product, indicating the involvement of a Ru-monohydride intermediate. Kinetic studies and DFT calculations suggest a low-energy bimetallic β-hydride elimination pathway where rate-limiting intramolecular proton transfer from alcohol to metal-bound hydride constitutes the dehydrogenation step. The general utility of metal-metal bonded compounds for alcohol AD and subsequent coupling reactions is demonstrated here.
- Dutta, Indranil,Sarbajna, Abir,Pandey, Pragati,Rahaman, S. M. Wahidur,Singh, Kuldeep,Bera, Jitendra K.
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p. 1505 - 1513
(2016/06/09)
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- Synthesis, characterization, and mechanism studies of bis(imino)pyridine ligands and their Cr(III) compounds
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Two new bis(imino)pyridine ligands L1, L2 (L1 = 2,6-bis[1-(4-bromophenylimino)]pyridine, L2 = 2,6-bis[1-(4-methylphenylimino)]pyridine) have been prepared. Their compounds [CrCl3L1] (I) and [Cr(Cl)(μ-Cl)(L2′)]2 (II) (L2′ = 6-bis(6-methylquinoline)pyridine) for olefin oligomerization were obtained by hydrothermal methods, during which L2′ was appeared from L2, and characterized by elemental analysis, single-crystal X-ray analysis (CIF files CCDC nos. 1025448 (I),1025447 (II)), IR spectra and melting point test. Compound I is a mononuclear compound, while compound II, bridged with the chlorine atoms, is a binuclear compound. The transformation mechanism between L2 and L2′ is also studied, and the possible reason is due to the presence of the electron-donating groups as substituents on L2. The subsequent studies on that will be carried on.
- Li, S. W.,Wang, Y. F.,Li, X. P.,Zhao, J. S.,Wang, J. L.
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p. 129 - 134
(2015/04/14)
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- Strain-Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines
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The displacement of molecular structures from their thermodynamically most stable state by imposition of various types of electronic and conformational constraints generates highly strained entities that tend to release the accumulated strain energy by undergoing either structural changes or chemical reactions. The latter case amounts to strain-induced reactivity (SIR) that may enforce specific chemical transformations. A particular case concerns dynamic covalent chemistry which may present SIR, whereby reversible reactions are activated by coupling to a high-energy state. We herewith describe such a dynamic covalent chemical (DCC) system involving the reversible imine formation reaction. It is based on the formation of strained macrocyclic bis-imine metal complexes in which the macrocyclic ligand is in a high energy form enforced by the coordination of the metal cation. Subsequent demetallation generates a highly strained free macrocycle that releases its accumulated strain energy by hydrolysis and reassembly into a resting state. Specifically, the metal-templated condensation of a dialdehyde with a linear diamine leads to a bis-imine [1+1]-macrocyclic complex in which the macrocyclic ligand is in a coordination-enforced strained conformation. Removal of the metal cation by a competing ligand yields a highly reactive [1+1]-macrocycle, which then undergoes hydrolysis to transient non-cyclic aminoaldehyde species, which then recondense to a strain-free [2+2]-macrocyclic resting state. The process can be monitored by 1H NMR spectroscopy. Energy differences between different conformational states have been evaluated by Hartree-Fock (HF) computations. One may note that the stabilisation of high-energy molecular forms by metal ion coordination followed by removal of the latter, offers a general procedure for producing out-of-equilibrium molecular states, the fate of which may then be examined, in particular when coupled to dynamic covalent chemical processes.
- Ratjen, Lars,Vantomme, Ghislaine,Lehn, Jean-Marie
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p. 10070 - 10081
(2015/07/07)
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- NOVEL LACTAM DERIVATIVES HAVING THERAPEUTIC EFFECT ON CANCERS
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The present invention relates to a novel lactam derivative having a cancer therapeutic effect or a pharmaceutically acceptable salt thereof and a pharmaceutical composition containing the same as an active ingredient. The novel lactam derivative in accordance with the present invention is capable of selectively and effectively inhibiting the growth of cancer cells, that is B-cell non-Hodgkinandprime;s lymphoma, thereby being usefully used as a pharmaceutical composition for treating cancer or inhibiting the growth of cancer cells.COPYRIGHT KIPO 2015
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- Regioselective Synthesis of V-Shaped Bistriazinyl-phenanthrolines
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A new, regioselective synthesis of V-shaped 2,9-bis(6-(4-halophenyl)-1,2,4-triazin-3-yl)-1,10-phenanthrolines (4XPhBTPhen) ligands was developed, creating access to a simple and reliable synthesis of precursors for future supramolecular actinide complexing systems. Described is a reactant-directed regioselective synthetic method, which was found to be high yielding and reliable and yields exclusively 6,6′-phenyl BTPhen derivatives (including 4-chloro and 4-bromo) in five simple steps. Molecular and crystal structures of PhBTP and PhBTPhen products are fully determined and both were found to be in space group C2/c. Additionally, molecular and crystal structures of Z and E isomers of 2-hydrazono-2-phenylacetaldehyde oxime, a reagent in the synthetic route, reveal existence of strong intramolecular N-H?O hydrogen bonding in the Z isomer explaining its lower solubility in water.
- Coogan, Niall T.,Chimes, Michael A.,Raftery, James,Mocilac, Pavle,Denecke, Melissa A.
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p. 8684 - 8693
(2015/09/15)
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- METHOD FOR THE CATALYTIC REDUCTION OF ACID CHLORIDES AND IMIDOYL CHLORIDES
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The present application relates to methods for the catalytic reduction of acid chlorides and/or imidoyl chlorides. The methods comprise reacting the acid chloride or imidoyl chloride with a silane reducing agent in the presence of a catalyst such as [Cp(Pri3P)Ru(NCMe)2]+[PF6]?.
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Paragraph 0104
(2014/08/19)
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- Tandem C-H activation/arylation catalyzed by low-valent iron complexes with bisiminopyridine ligands
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Tandem C-H activation/arylation between unactivated arenes and aryl halides catalyzed by iron complexes that bear redox-active non-innocent bisiminopyridine ligands is reported. Similar reactions catalyzed by first-row transition metals have been shown to involve substrate-based aryl radicals, whereas our catalytic system likely involves ligand-centered radicals. Preliminary mechanistic investigations based on spectroscopic and reactivity studies, in conjunction with DFT calculations, led us to propose that the reaction could proceed through an inner-sphere C-H activation pathway, which is rarely observed in the case of iron complexes. This bielectronic noble-metal-like behavior could be sustained by the redox-active non-innocent bisiminopyridine ligands. A radical choice! A low-valent iron complex with non-innocent bisiminopyridine ligands performs C-H activation/arylation of unactivated aryl compounds (see figure). The reaction likely involves ligand-based radicals, whereas previously reported iron-based systems imply substrate-based radicals.
- Salanouve, Elise,Bouzemame, Ghania,Blanchard, Sebastien,Derat, Etienne,Desage-El Murr, Marine,Fensterbank, Louis
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supporting information
p. 4754 - 4761
(2014/05/06)
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- Recognition between V- and dumbbell-shaped molecules
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A series of 2,6-bis(imino)pyridyl-based V-shaped compounds bearing various para-substituents on the terminal aromatic rings [C5H 3N(CHN-C6H4R)2; R = OMe, iPr, Me, H, Cl, F, and CF3] have been prepared and investigated for their reversible binding with the dumbbell-shaped cations NH2+-{CH2-C6H3(OMe-3,5) 2}2 and 9-anthryl-CH2-NH2 +-CH2-C6H3(OMe-3,5)2. Three crystalline V-shaped compounds and a dumbbell hexafluorophosphate were characterised in the solid state by X-ray structural analysis. The binding mode of the 1 : 1 V-shaped molecule·dumbbell complexes was evaluated by 1H NMR spectroscopy. The binding constants (90-400 M-1 in dichloromethane) and stoichiometries of the complexes were determined using the Method of Continuous Variations and the Rose-Drago Method based on 1H NMR spectroscopic data. In a series of V-shaped compounds, the binding strength with both dumbbell cations diminishes with the decreasing electron-donating ability of the R substituents. Specifically, one of the diimine V-shaped compounds shows a stronger binding with the symmetrical dumbbell than with the unsymmetrical anthracene-containing dumbbell. Fluorescence measurements of equimolar mixtures of the V-shaped compounds and the unsymmetrical dumbbell have revealed a reduced anthracene emission which is approximately 50% that of the original intensity. Rapid and complete dissociation (5 min) of the V-shaped compounds from the dumbbells was realised using an excess of acid or base, whereas only partial dissociation of the complexes was achieved with a large excess of water (1 h).
- Wong, Wing-Yan,Lee, Siu-Fung,Chan, Hoi-Shan,Mak, Thomas C.W.,Wong, Chi-Hin,Huang, Lau-Shan,Stoddart, J. Fraser,Leung, Ken Cham-Fai
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p. 26382 - 26390
(2013/12/04)
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- Immobilized into montmorillonite Mn(II) complexes of novel pyridine schiff-base ligands and their catalytic reactivity in epoxidation of cyclohexene with O2
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Mild temperature and atmospheric oxygen pressure assisted epoxidation of cyclohexene was achieved with a series of novel montmorillonite-supported Mn(II) complexes of pyridine Schiff-base ligands. The catalysts were characterized by IR, UV-Vis DRS, XRD, SEM and ICP. The heterogeneous catalysts were proved to promote the epoxidation of cyclohexene efficiently, affording the desired product epoxycyclohexane with a yield up to 92 %. The effects of various reaction conditions on the catalytic reaction were optimized. Repeated runs indicated that the catalysts were stable for 3 cycles without noticeable loss of their catalytic activity.
- Li, Zhongying,Tang, Ruiren,Liu, Guiyin
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p. 592 - 599
(2013/07/19)
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- Novel pyridine Schiff base-manganese(ii) complexes: Synthesis, characterization and catalytic reactivity of the epoxidation of cyclohexene
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Four novel pyridine Schiff bases derived from 2,6-pyridinedicarbaldehyde and substituted o-hydroxyl-aromatic amines and their manganese(ii) complexes were synthesized and characterized by elemental analyses, ESI-MS analysis, thermal analysis (TGA), H-NMR, IR and UV-vis. The activity of these complexes as catalysts in cyclohexene autoxidation were investigated and the effects of various reaction conditions on the catalytic reaction were optimized to obtain as high as 99.6% conversion with 95.0% selectivity of epoxycyclohexane at 40°C for 6 h using molecular oxygen as an oxidant in acetonitrile. The result presents excellent catalysts for epoxidation of cyclohexene under mild temperature and atmospheric oxygen (O2) pressure.
- Li, Zhongying,Liu, Changhui,Tang, Ruiren,Liu, Guiyin
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p. 9745 - 9751
(2013/09/02)
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- A convenient approach for the synthesis of 2,6-diformyl- and 2,6-diacetylpyridines
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2,6-Diformyl- and 2,6-diacetylpyridines are readily accessed in good yields (60-90%) via the single-pot reaction of 2,6-pyridine dicarboxamides with LiAlH4 or MeMgCl in THF at 0-20°C. The high efficiency of the method illustrates the significance of solubility in the reduction and alkylation of difunctionalized substrates.
- Ivchenko, Pavel V.,Nifant'Ev, Ilya E.,Buslov, Ivan V.
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p. 217 - 219
(2013/02/23)
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- Stabilized hemiacetal complexes as precursors for the controlled release of bioactive volatile alcohols
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Hemiacetals of pyridine-2-carbaldehyde derivatives and volatile alcohols can be stabilized in organic solution in the presence of protons or different metal cations. Despite the inherent instability of hemiacetals in H 2O, stabilizing them with zinc(II) triflate and adding them to a cationic surfactant formulation resulted in the slow release of the alcohol from cotton surfaces being treated with the hemiacetal complex. Stabilized hemiacetals might thus be suitable delivery systems of bioactive volatiles by rapid hydrolysis in H2O-based media.
- Buchs, Barbara,Fieber, Wolfgang,Drahonovsky, Dusan,Lehn, Jean-Marie,Herrmann, Andreas
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scheme or table
p. 689 - 701
(2012/08/08)
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- N-heterocyclic carbene catalyzed C-glycosylation: A concise approach from stetter reaction
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Described herein is the first example of an organocatalytic approach for acylanion addition to the anomeric carbon of 2-nitroglucal using an N-heterocyclic carbene catalyst. Control over the reaction conditions gives β-selective and nitro-eliminated C-glycosides, providing opportunities to produce new classes of C-glycoside.
- Vedachalam, Seenuvasan,Tan, Shi Min,Teo, Hui Ping,Cai, Shuting,Liu, Xue-Wei
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supporting information; experimental part
p. 174 - 177
(2012/02/16)
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- Chemoselective ruthenium-catalyzed reduction of acid chlorides to aldehydes with dimethylphenylsilane
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A variety of aromatic and alkyl acid chlorides can be selectively converted into aldehydes using dimethylphenyl silane (HSiMe2Ph) as the reducing reagent in the presence of the cationic ruthenium catalyst {Cp[(i-Pr)3P]Ru(NCMe)2}+ [PF6] -. The reactions proceed under very mild conditions and are tolerant to many functional groups. Copyright
- Gutsulyak, Dmitry V.,Nikonov, Georgii I.
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experimental part
p. 607 - 611
(2012/04/23)
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- An acyclic oligoheteroaryle that discriminates strongly between diverse G-Quadruplex topologies
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Feeling groovy: A family of nonmacrocyclic G-quadruplex binders with alternate oxazole and pyridine motifs was prepared. The shown heptacyclic derivative exhibits an unprecedented binding preference for certain quadruplex topologies: it recognizes exclusively the human telomeric quadruplex in Na + buffer but not in K+ buffer. This unique quadruplex binding profile is strongly dependent on the size of the ligand and may result from groove interactions. Copyright
- Hamon, Florian,Largy, Eric,Guedin-Beaurepaire, Aurore,Rouchon-Dagois, Myriam,Sidibe, Assitan,Monchaud, David,Mergny, Jean-Louis,Riou, Jean-Francois,Nguyen, Chi-Hung,Teulade-Fichou, Marie-Paule
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supporting information; experimental part
p. 8745 - 8749
(2011/11/06)
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- Novel and efficient procedure for the preparation of two pyridine dicarboxylic acid derivatives
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New strategies for the synthesis of two pyridine dicarboxylic acid derivatives namely; 4-(2-(2,6-dicarboxypyridin-4-yl)vinyl)pyridine-2,6- dicarboxylic acid and 2,6-bis(2-(2,6-dicarboxy-pyridin-4-yl)vinyl)pyridine have been described. New oxidant used is a good example of green chemistry technology and the synthesis procedure harvest a high-purity product at a high yield.
- Guoliang,Ming
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experimental part
p. 449 - 452
(2012/02/01)
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- Carbohydrate-based spiro bis(isoxazolines): synthesis and evaluation in asymmetric catalysis
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Two carbohydrate-based spiro bis(isoxazolines) were synthesized via 1,3-dipolar cycloaddition from peracetylated methylene exo-glucal and the corresponding bis(arylnitrile oxide). The bis(cycloadducts) were then evaluated as ligands for enantioselective catalytic reactions. The Pd-catalyzed Tsuji-Trost reaction between a malonate and an allylic acetate did not provide good results. The poor conversion observed can be attributed to the rearrangement of the ligand in the reaction mixture to afford the corresponding ring-opened isoxazole which has been characterized. Both ligands were also evaluated in Cu(I)-catalyzed asymmetric imine alkynylation and afforded the product in good yield and modest enantioselectivity.
- Goyard, David,Telligmann, Susanne M.,Goux-Henry, Catherine,Boysen, Mike M.K.,Framery, Eric,Gueyrard, David,Vidal, Sébastien
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supporting information; experimental part
p. 374 - 377
(2010/03/24)
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- Self-sorting of equilibrating metallosupramolecular DCLs via constitutional crystallization
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Zn2+ and Pb2+ and ligands 1 and 2 self-assemble in solution to generate DCLs of interexchanging metallosupramolecular subcomponents, which convert into robust species of unique stoichiometry via constitutional crystallization.
- Barboiu, Mihail,Dumitru, Florina,Legrand, Yves-Marie,Petit, Eddy,Van Der Lee, Arie
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supporting information; experimental part
p. 2192 - 2194
(2009/09/05)
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- Synthesis of dicyanopyridines
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Synthesis of the title compounds in four steps using inexpensive collidine and lutidine as starting materials is described.
- Roblou, Emmanuel,Sasaki, Isabelle,Pezet, Frederic,Ait-Haddou, Hassan,Vincendeau, Sandrine
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p. 3743 - 3749
(2007/10/03)
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- Synthesis of multitopic verdazyl radical ligands. Paramagnetic supramolecular synthons
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Equation presented. The syntheses of several verdazyl radical and diradicals containing pyridine-based multitopic coordination sites are described. These compounds were designed to be paramagnetic analogues of oligopyridine metallosupramolecular building blocks.
- Hicks, Robin G.,Koivisto, Bryan D.,Lemaire, Martin T.
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p. 1887 - 1890
(2007/10/03)
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- A facile and selective synthetic method for the preparation of aromatic dialdehydes from diesters via the amine-modified SMEAH reduction system
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A new reduction system employing N-methylpiperazine-modified sodium bis(2-methoxyethoxy)aluminum hydride (NMP-SMEAH) for the conversion of aromatic diesters to dialdehydes is described. The method is plain and efficient, and can be carried out under mild and operationally simple conditions applicable for large scale productions.
- Hagiya, Kazutake,Mitsui, Sunao,Taguchi, Hiroaki
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p. 823 - 828
(2007/10/03)
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- POLYMERISATION CATALYSTS
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Catalyst systems useful for the polymerisation of 1-olefins are disclosed, which contain nitrogen-containing transition metal compounds comprising the skeletal unit depicted in Formula (B), wherein M is Fe[II], Fe[III], Ru[II], Ru[III] or Ru[IV]; X represents an atom or group covalently or ionically bonded to the transition metal M; T is the oxidation state of the transition metal M and b is the valency of the atom or group X; R, R, R, Rand Rare independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl; Rand Rare independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl.
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- Ligands based on chiral 2-amino-2′-hydroxy-1,1′-binaphthyl and related frameworks for asymmetric catalysis
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The present invention includes array of new chiral ligands that are optically active or racemic. These ligands are bidentate, tridentate, tetradentate or pentadentate ligands which include P-P, P-N, N-N, mixed P-N, Schiff base or carbene sites. The present invention further includes a catalyst prepared by a process, which includes contacting a transition metal salt, or a complex thereof, and a ligand according to the present invention. The present invention still further includes a process for preparation of an asymmetric compound. In this process, a substrate capable of forming an asymmetric product by an asymmetric reaction and a catalyst according to the present invention are contacted to produce an asymmetric product. Transition metal complexes with these ligands are effective catalysts for asymmetric reactions. Applicant has discovered that asymmetric products can be prepared using the chiral catalysts according to the present invention in enantioselective reactions, such as hydrogenation, hydroformylation, Michael addition, Heck reaction, Aldol reaction, allylic alkylation, cyclopropanation, epoxidation, and olefin metathesis.
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- Synthesis of a muscarinic receptor antagonist via a diastereoselective Michael reaction, selective deoxyfluorination and aromatic metal-halogen exchange reaction
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An efficient synthesis of a structurally unique, novel M3 antagonist 1 is described. Compound 1 is conveniently disconnected retrosynthetically at the amide bond to reveal the acid portion 2 and the amine fragment 3. The synthesis of key intermediate 2 is highlighted by a ZnCl2-MAEP complex 19 catalyzed diastereoselective Michael reaction of dioxolane 7 with 2-cyclopenten-1-one (5) to establish the contiguous quaternary-tertiary chiral centers and a subsequent geminal difluorination of ketone 17 using Deoxofluor in the presence of catalytic BF3·OEt2. The synthesis of the amine moiety 3 is highlighted by the discovery of a novel n-Bu3MgLi magnesium-halogen exchange reaction for selective functionalization of 2,6-dibromopyridine. This new and practical metalation protocol obviated cryogenic conditions and upon quenching with DMF gave 6-bromo-2-formylpyridine (26) in excellent yield. Further transformations afforded the amine fragment 3 via reductive amination with 35, Pd-catalyzed aromatic amination, and deprotection. Finally, the highly convergent synthesis of 1 was accomplished by coupling of the two fragments. This synthesis has been used to prepare multi-kilogram quantities of the bulk drug.
- Mase,Houpis,Akao,Dorziotis,Emerson,Hoang,Iida,Itoh,Kamei,Kato,Kato,Kawasaki,Lang,Lee,Lynch,Maligres,Molina,Nemoto,Okada,Reamer,Song,Tschaen,Wada,Zewge,Volante,Reider,Tomimoto
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p. 6775 - 6786
(2007/10/03)
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- Tributylmagnesium ate complex-mediated novel bromine-magnesium exchange reaction for selective monosubstitution of dibromoarenes
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Lithium tributylmagnesate complex (n-Bu3MgLi), readily prepared from n-BuLi and n-BuMgCl (2:1), is a novel metallation agent. It is quite efficient for the selective mono-bromine-magnesium exchange of 2,6-dibromopyridine (1) under non-cryogenic conditions (at -10°C) to give a stable magnesate intermediate. Subsequent treatment with DMF gave 6-bromo-2-formylpyridine (3) in excellent yield. This method is also applicable for selective monosubstitution of several other kinds of dibromoarenes.
- Iida, Takehiko,Wada, Toshihiro,Tomimoto, Koji,Mase, Toshiaki
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p. 4841 - 4844
(2007/10/03)
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- Mild and convenient oxidation of aromatic heterocyclic primary alcohols by 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium perchlorate
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Hydroxymethyl substituted aromatic heterocycles, including pyridines, furans, and thiophenes, are oxidized to the corresponding aldehydes in excellent yields by 4-acetylamino-2,2,6,6-tetramethylpiperidine-1- oxoammonium perchlorate (1) with minimal workup.
- Kernag, Casey A.,Bobbitt, James M.,McGrath, Dominic V.
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p. 1635 - 1636
(2007/10/03)
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- Synthesis, Basicity, and Conformation of New Concave Pyridines
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Eight new bimacrocyclic concave pyridines 9 and six monomacrocyclic and open-chain analogues 10-12 were synthesized in overall yields up to 40percent (up to 75percent for nonmacrocyclic pyridines) starting from 2,6-pyridinedicarbaldehydes 1, diamines 2 and diacyl dichlorides 7.Their basicities cover a range of more than three orders of magnitude.They are determined not only by the substitution pattern of the pyridine ring, but also by the overall structure of the whole molecule and by its ability to stabilize the positive charge of a proton intramolecularly.The conformations ofthe bimacrocyclic bislactams 9 in solution and in the solid state were investigated spectroscopically, the structure of 9b could be determined by X-ray analysis.
- Luening, Ulrich,Baumstark, Roland,Peters, Karl,Schnering, Hans Georg von
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p. 129 - 143
(2007/10/02)
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- FACILE REDUCTION OF ACID CHLORIDES INTO ALDEHYDES USING HYPERVALENT SILICON HYDRIDES.
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Acyl chlorides have been reduced to aldehydes by a simple exchange reaction with pentacoordinated silicon hydrides
- Corriu, R. J. P.,Lanneau, G. F.,Perrot, M.
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p. 1271 - 1274
(2007/10/02)
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