- Suzuki-Miyaura coupling reactions in aqueous microdroplets with catalytically active fluorous interfaces
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Using microfluidic techniques and a novel fluorous-tagged palladium catalyst, we generated droplet reactors with catalytically active walls and used these compartments for small molecule synthesis.
- Theberge, Ashleigh B.,Whyte, Graeme,Frenzel, Max,Fidalgo, Luis M.,Wootton, Robert C. R.,Huck, Wilhelm T. S.
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- Isotopic probing of molecular oxygen activation at copper(I) sites
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Copper-dioxygen (CuO2) adducts are frequently proposed as intermediates in enzymes, yet their electronic and vibrational structures have not always been understood. [Cu(η1-O2)TMG 3tren]+ (TMG3-tren = 1,1,1-tris{2-[N 2-(1,1,3,3-tetramethylguanidino)]ethyl}amine) features end-on (η1) O2 coordination in the solid state. Described here is an investigation of the compound's solution properties by nuclear magnetic resonance spectroscopy, density functional calculations, and oxygen isotope effects. The study yields two major findings. First, [Cu(η1-O2)TMG3tren]+ is paramagnetic due to a triplet electronic structure; this is in contrast to other copper compounds where O2 is bound in a side-on manner. Second, the oxygen equilibrium isotope effect upon O2 binding to copper(I) ( 18O EIE = K(16O16O)/K(16O 18O) = 1.0148 ± 0.0012) is significantly larger than those determined for iron and cobalt η1-O2 adducts. This result is suggested to reflect greater ionic (CuII-O2 -I) character within the valence bond description. A revised interpretation of the physical origins of the 18O EIEs upon O 2 binding to redox metals is also advanced along with experimental data that should be used as benchmarks for interpreting 18O kinetic isotope effects upon enzyme reactions.
- Lanci, Michael P.,Smirnov, Valeriy V.,Cramer, Christopher J.,Gauchenova, Ekaterina V.,Sundermeyer, Joerg,Roth, Justine P.
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- Bent and twisted: The electronic structure of 2-azapropenylium ions obtained by guanidine oxidation
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New bis-2-azapropenylium ions are obtained by oxidation of guanidino-substituted aromatic compounds. The dications 12+ (1 = 1,4-bis-tetramethylguanidinobenzene) and 22+ (2 = 1,4-bis-guanidinobenzene) exhibit unexpected bent-twisted structures, that differ from the known 2-azapropenylium ion structures (linear-orthogonal 2-azaallenium ion or bent-planar 2-azaallylium ion), and resemble the structures of carbodicarbenes. Their electronic structure was analysed by a combination of experiments and quantum chemical calculations. The results indicate that the bent-planar structure is disfavoured for steric reasons, while the allene-type linear-orthogonal structure is also disfavoured due to the electron-donating groups that support the bent form. For these reasons a bent-twisted structure is adopted, in which the nitrogen atom is engaged with two different orbitals in π-bonding with the carbon π-system and in a weaker π-interaction with the CN2 group of the guanidino system.
- Hornung, Julius,Hübner, Olaf,Kaifer, Elisabeth,Himmel, Hans-J?rg
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- A solvent having switchable hydrophilicity
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A new kind of switchable solvent, a switchable-hydrophilicity solvent, is hydrophobic and has very low miscibility with water when in air but is hydrophilic and has complete miscibility with water when under an atmosphere of CO2. We report here the first example of such a solvent, N,N,N′-tributylpentanamidine. Solvents such as these could be used for the extraction of low-polarity organic products, such as vegetable oils, followed by the removal of the solvent from the product by carbonated water. Carbonated water is able to extract the solvent from the product because the CO2 converts the solvent to its hydrophilic form. The solvent can then be separated from the carbonated water upon removal of the CO2, because this removal triggers the conversion of the solvent back to its hydrophobic, water-immiscible form. Importantly, distillation is not required for removal of the solvent from the product.
- Jessop, Philip G.,Phan, Lam,Carrier, Andrew,Robinson, Shona,Duerr, Christoph J.,Harjani, Jitendra R.
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- Construction of copper chains with new fluorescent guanidino-functionalized naphthyridine ligands
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The three new blue-fluorescent ligands 2,7-bis(tetramethylguanidino)-1,8-naphthyridine (1), 2,7-bis(N,N′-dimethylethylene-guanidino)-1,8-naphthyridine (2) and 2,7-bis(N,N′-diisopropylguanidino)-1,8-naphthyridine (3) are synthesized, and their optical properties (electronic absorption and emission spectroscopy) studied. Reactions of 1 or 2 with [Cu(CH3CN)4]BF4 yield the Cu4 chain compounds [Cu4(1)2](BF4)4 (that crystallizes as [Cu4(1)2(CH3CN)2](BF4)4·2CH2Cl2) and [Cu4(2)2](BF4)4. The variations of the optical properties upon coordination are evaluated, and the electronic transitions identified by time-dependent DFT (TD-DFT) calculations. Then the redox properties of the new Cu4 chain complexes are studied. In the course of these experiments, the new Cu6 complex [Cu4(1)2(CuCl2)2]2+, in which two CuCl2- units coordinate to the Cu4 chain in [Cu4(1)2]4+, was fully characterized. In addition, the Cu3 chain complexes [Cu3(1)3]3+ and [Cu3(1)2]3+ were isolated as products of redox-induced degradation processes. Finally, we show by quantum chemical calculations that in [M4(1)2]4+ complexes (M = coinage metal), the HOMO changes from a ligand-centered to a metal-centered orbital for replacement of M = Cu by Au.
- Kr?mer, Christoph,Leingang, Simone,Hübner, Olaf,Kaifer, Elisabeth,Wadepohl, Hubert,Himmel, Hans-J?rg
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- A Convenient procedure for the preparation of bis(dialkylamino) malononitriles
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N,N,N++,N++-Tetraalkylchloroformamidinium chlorides react with trimethylsilyl cyanide without solvent to give bis(dialkylamino) malononitriles, which can be distilled off from the reaction mixture in vacuo. Georg Thieme Verlag Stuttgart.
- Tiritiris, Ioannis,Kantlehner, Willi
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- Complexes of manganese, iron, zinc, and molybdenum with a superbasic tris(guanidine) derivative of tris(2-ethylamino)amine (tren) as a tripod ligand
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The synthesis of the novel tripod ligand N[CH2CH2N=C(NMe2)2]3, based on the tris(2-ethylamino)amine (tren) backbone and having a set of three superbasic tetramethylguanidine (TMG) donor atoms instead of the primary amine functionalities, is described. This ligand has been prepared by treating tren with the Vilsmeyer salt [(Me2N)2CCl]Cl in the presence of triethylamine as an auxiliary base and NaOH. Complexes of manganese(II), iron(II), and zinc(II) as biologically relevant transition metal ions as well as of molybdenum(0) have been synthesized and spectroscopically and structurally characterized. The electrochemical properties of selected complexes have been studied.
- Wittmann, Harald,Raab, Volker,Schorm, Andrea,Plackmeyer, Joern,Sundermeyer, Joerg
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- Trinuclear complexes and coordination polymers of redox-active guanidino-functionalized aromatic (GFA) compounds with a triphenylene core
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Herein, we report on the synthesis, redox activity, and coo r d i n a t i o n c h e m i s t r y of 2, 3 , 6 , 7 , 1 0 , 1 1 - h e x a k i s - (tetramethylguanidino)triphenylene. CV measurements indicated that the new compound could be oxidized in three se
- Lebkücher, Anna,Wagner, Christoph,Hübner, Olaf,Kaifer, Elisabeth,Himmel, Hans-J?rg
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- Spectroscopic capture and reactivity of S = 1/2 nickel(iii)-oxygen intermediates in the reaction of a NiII-salt with mCPBA
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Ni(iii)-intermediates are trapped by EPR and UV/Vis spectroscopy in the reaction of a Ni(ii) salt with mCPBA. On the basis of their oxo-transfer and hydrogen-atom abstraction abilities the intermediates are assigned as the elusive terminal Ni(iii)-oxo/hydroxo species. The findings suggest that Ni(iii)-O(H) moieties are viable reactants in oxidation catalysis. The Royal Society of Chemistry 2012.
- Pfaff, Florian Felix,Heims, Florian,Kundu, Subrata,Mebs, Stefan,Ray, Kallol
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- Probing the Proton-Coupled Electron-Transfer (PCET) Reactivity of a Cross-Conjugated Cruciform Chromophore by Redox-State-Dependent Fluorescence
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Proton-coupled electron transfer (PCET) reactions are of great importance in synthetic chemistry and in biology, but the acquisition of kinetic information for these reactions is often difficult. Herein, we report the synthesis of a new PCET reagent, showing redox-state dependent fluorescence, by merging the concept of cross-conjugated cruciform chromophores with the strategy of imposing redox activity and Br?nsted basicity to aromatic compounds by substitution with guanidino groups. The compound is isolated and characterized in all stable states—reduced, twofold and fourfold protonated and twofold oxidized—and then applied in PCET reactions by using its redox-state dependent fluorescence signal for kinetic measurements.
- Wagner, Conrad,Hübner, Olaf,Kaifer, Elisabeth,Himmel, Hans-J?rg
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- The synthesis and structural characterization of peralkylated triguanide superbases
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Organic superbases derived from a peralkylated triguanide framework have been synthesized in a coupling reaction between monosubstituted guanidines and a Vilsmeier salt. Single crystal X-ray diffraction analysis of the chloride salt allowed the structural
- Strukil, Vjekoslav,Leksic, Edislav,Mestrovic, Ernest,Eckert-Maksic, Mirjana
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- Copper Complexes of New Redox-Active 4,5-Bisguanidino-Substituted Benzodioxole Ligands: Control of the Electronic Structure by Counter-Ligands, Solvent, and Temperature
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Herein, we analyze the possibility of controlling the electronic structure of mononuclear copper complexes featuring new redox-active 4,5-bisguanidino-substituted benzodioxole ligands. The nature of the guanidino groups, the anionic counter-ligands, the applied solvent (polarity), and the temperature are the parameters that decide if a CuIIcomplex with neutral ligand unit or a CuIcomplex with radical monocationic ligand unit is the adequate description. Under special conditions, a temperature-dependent equilibrium of the two valence tautomeric forms (CuII/neutral ligand and CuI/radical monocationic ligand) is achieved. Removal of a ligand-centered electron from a paramagnetic CuIIcomplex with a neutral ligand unit leads to a diamagnetic CuIcomplex with a dicationic ligand unit through a redox-induced electron-transfer (RIET) process.
- Schrempp, David Fridolin,Kaifer, Elisabeth,Wadepohl, Hubert,Himmel, Hans-J?rg
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- Tetra(amino)methanes: Implications of their structure and reactivity pattern for hypothetical carbon nitride frameworks
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Because of their possible role as model compounds for the structural units of carbon nitride C3N4, the preparation, structural chemistry, and some representative reactions of tetra(amino)methanes have been (re)investigated. In the crystal, C(NMe2)4 (1) has a molecular geometry close to D2d symmetry as proposed by theoretical calculations using state-of-the-art density functional methods. The coordination of the central carbon atom is distorted tetrahedral and the configuration of the nitrogen atoms is strongly pyramidal, as opposed to almost planar in the tetra(amino)silanes. Tetra(pyrrolidinyljmethane has a similar core structure, with all heterocyclic substituents in an envelop conformation flexible in solution. Tetra(piperidinyl)methane is more rigid in solution, owing to a more congested structure, with much higher inversion barriers for the six-membered rings. Hydrolysis of 1 leads to Me2NH and hexamethylguanidinium hydroxide, and treatment of 1 with HAuCl4(aq) affords crystalline [C(NMe2)3]+ AuCl4-, the structure of which has also been determined. Compound 1 is a strong nucleophile and can be used as an aminating agent, converting e.g. halosilanes into dimethylaminosilanes, with the guanidinium cation as the leaving group. The experimental results are discussed in the light of recent predictions regarding bulk carbon nitrides. WILEY-VCH Verlag GmbH, 1997.
- Jockisch, Alexander,Schier, Annette,Schmidbaur, Hubert
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- 4,4′,5,5′-tetrakis(guanidinyl)binaphthyl-synthesis and properties of two redox-active ligands and oxidative C-C coupling to perylene derivatives
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We report the synthesis and properties of the new redox-active ligands 4,4′,5,5′-tetrakis(tetramethylguanidinyl)binaphthyl and 4,4′,5,5′-tetrakis(N,N′-dimethylethyleneguanidinyl)binaphthyl. The first dinuclear zinc complexes were prepared. Oxidative C-C coupling of these compounds leads to perylene derivatives.
- Wiesner, Sven,Ziesak, Alexandra,Reinmuth, Matthias,Walter, Petra,Kaifer, Elisabeth,Wadepohl, Hubert,Himmel, Hans-Joerg
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- 1,8-Bis(tetramethylguanidino)naphthalene (TMGN): A new, superbasic and kinetically active "proton sponge"
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1,8-Bis(tetramethylguanidino)naphthalene (TMGN, 1) is a new, readily accessible, and stable "proton sponge" with an experimental pKBH+ value of 25.1 in MeCN, which is nearly seven orders of magnitude higher in basicity than the classical proton sponge 1,8-bis(dimethylamino)-naphthalene (DMAN). Because of the sterically less crowded character of the proton-accepting sp2-nitrogen atoms, TMGN also has a higher kinetic basicity than DMAN, which is shown by time-resolved proton self-exchange reactions. TMGN is more resistant to hydrolysis and is a weaker nucleophile towards the alkylating agent EtI in comparison to the commercially available guanidine 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). Crystal structures of the free base, of the mono- and bisprotonated base were determined. The dynamic behavior of all three species in solution was investigated by variable-temperature 1H NMR experiments. ΔG≠ values obtained by spectra simulation reveal a concerted mechanism of rotation about the C-N bonds of the protonated forms of TMGN.
- Raab, Volker,Kipke, Jennifer,Gschwind, Ruth M.,Sundermeyer, Joerg
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- Bidentate guanidine ligands with ethylene spacer in copper-dioxygen chemistry: Structural characterization of bis(μ-hydroxo) dicopper complexes
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The syntheses of the aliphatic bidentate guanidine-amine-hybrid ligands DMEGdmae (L1), TMGdmae (L2), TMGdeae (L3) and DPipGdmae (L4) as well as the reaction of their Cu(I) complexes with molecular oxygen (monitored by UV-Vis spectroscopy) are reported. The molecular structures of 10 bis(μ-hydroxo) dicopper complexes based on these ligands are described. The solid state structures of [Cu2(μ-OH)2(DMEGdmae)2]X 2 (X- = I- (1), CF3SO 3- (2), SbF6- (3), PF 6- (4)), [Cu2(μ-OH)2(TMGdmae) 2]X2 (X- = I- (5), CF 3SO3- (6)), [Cu2(μ-OH) 2(TMGdeae)2]Cu2I4 (7) and [Cu 2(μ-OH)2(DPipGdmae)2]X2 (X - = CF3SO3- (8), SbF 6- (9), PF6- (10)) show a square-planar distorted coordination of the copper(II) ion. The bis(μ-hydroxo) dicopper complex 1 exhibits a Cu?Cu distance of 2.860(1) , which is one of the smallest observed for hydroxo-bridged copper compounds so far. The influence of the anion on the structure of the bis(μ-hydroxo) dicopper(II) unit is analyzed for the reported complexes and a literature overview with emphasis on the structural characteristics of the Cu2O2 moiety of bis(μ-hydroxo) dicopper(II) and bis(μ-oxo) dicopper(III) is given.
- Haase, Roxana,Beschnitt, Tanja,Fl?rke, Ulrich,Herres-Pawlis, Sonja
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- Investigation of a family of structurally-related guanidinium ionic liquids through XPS and thermal analysis
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A family of structurally-related guanidinium bistriflimide ionic liquids has been prepared and characterized. TGA analyses showed a high thermal stability for all the proposed ionic liquids while DSC and XPS analyses divided them into distinct subsets depending on whether one or more constraining cycles were present. The results obtained highlighted the influence of the cation structure on some of the physico-chemical properties and thus the possibility to tune them by selecting proper substituents. The solvatochromic parameters of a selected guanidinium IL have also been studied.
- Moscardini, Aldo,Mezzetta, Andrea,Calisi, Nicola,Caporali, Stefano,Pomelli, Christian Silvio,Guazzelli, Lorenzo,Chiappe, Cinzia
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- Crystal structure of hexamethylguanidinium hexafluorosilicate hexahydrate
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Single crystals of the hexamethylguanidinium hexafluorosilicate hexahydrate salt, [C(NMe2)3+]2SiF6 2-·6H2O, were isolated when a product, obtained by water removal from aqueous [C(NMe2)3]F in a glass vessel, was recrystallized from CH3OH. The crystal structure of this salt was determined, and the geometry of the free hexamethylguanidinium cation was calculated, showing that its observed propeller-shaped arrangement is not caused by solid state effects but is the true minimum energy structure of the free ion.
- Zhang, Xiongzhi,Bau, Robert,A. Sheehy, Jeffrey,Christe, Karl O.
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- On the Metal Cooperativity in a Dinuclear Copper–Guanidine Complex for Aliphatic C?H Bond Cleavage by Dioxygen
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Selective oxidation reactions of organic compounds with dioxygen using molecular copper complexes are of relevance to synthetic chemistry as well as enzymatic reactivity. In the enzyme peptidylglycine α-hydroxylating monooxygenase (PHM), the hydroxylating activity towards aliphatic substrates arises from the cooperative effect between two copper atoms, but the detailed mechanism has yet to be fully clarified. Herein, we report on a model complex showing hydroxylation of an aliphatic ligand initiated by dioxygen. According to DFT calculations, the proton-coupled electron-transfer (PCET) process leading to ligand hydroxylation in this complex benefits from cooperative effects between the two copper atoms. While one copper atom is responsible for dioxygen binding and activation, the other stabilizes the product of intramolecular PCET by copper–ligand charge transfer. The results of this work might pave the way for the directed utilization of cooperative effects in oxidation reactions.
- Sch?n, Florian,Biebl, Florian,Greb, Lutz,Leingang, Simone,Grimm-Lebsanft, Benjamin,Teubner, Melissa,Buchenau, S?ren,Kaifer, Elisabeth,Rübhausen, Michael A.,Himmel, Hans-J?rg
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p. 11257 - 11268
(2019/07/18)
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- Redox-Active Guanidines with One or Two Guanidino Groups and Their Integration in Low-Dimensional Perovskite Structures
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Redox-active guanidines are versatile reagents in redox and proton-coupled electron-transfer (PCET) reactions. Recently, they were integrated as sacrificial electron donors for the prohibition of metal oxidation in perovskite materials. Herein we report t
- Walter, Petra,Kaifer, Elisabeth,Herrmann, Hendrik,Wadepohl, Hubert,Hübner, Olaf,Himmel, Hans-J?rg
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p. 4147 - 4160
(2019/11/03)
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- Guanidine salt ionic liquid as well as preparation method and application thereof
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The invention relates to guanidine salt ionic liquid as well as a preparation method and application thereof. The specific structure of the guanidine salt ionic liquid is shown in the specification, wherein n is 0, 1 or 2; n is 1 or 2; Y is BF4, PF6, TFSI, FSI or N (CN)2. According to the preparation method, branched chain alkyl is introduced through reaction of 2-aminobutane; alkylation reaction in a traditional method is changed, and ether functional groups are introduced through halogen substitution reaction. The guanidine salt ionic liquid is used as an additive, and a small amount of an ionic liquid, a lithium salt and an organic solvent are used as electrolyte of a lithium battery, so that the advantages of low viscosity and good electrochemical performance are achieved.
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Paragraph 0093-0094; 0101-0102; 0107-0108; 0113-0114
(2019/12/25)
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- De novo synthesis of 2,2-bis(dimethylamino)-3-alkyl or benzyl 2,3-dihydroquinazolin-4(1H)-one compounds
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A new versatile and efficient strategy for the synthesis of 2,2-bis(dimethylamino)-3-alkyl or benzyl 2,3-dihydroquinazoline-4(1H)-one compounds has been developed by one-pot multicomponent reaction with isatoic anhydride, amines followed by in situ-generated Vilsmeier reagent. The reaction has also been studied with different amines and solvents.
- Jaganmohan, Chikkanti,Vinay Kumar,Sandeep Reddy,Mohanty, Sandeep,Kumar, Jaydeep,Venkateswara, Rao,Tadiparthi, Krishnaji,Raghunadh, Akula
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supporting information
p. 168 - 174
(2018/01/01)
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- A Stable Hexakis(guanidino)benzene: Realization of the Strongest Neutral Organic Four-Electron Donor
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The growing demand for efficient batteries has stimulated the search for redox-active organic compounds with multistage redox behavior, as materials with large charge capacity. Herein we report the synthesis and properties of the first hexakis(guanidino)benzene derivative: a strong neutral organic electron donor with reversible multistage redox behavior and a record low redox potential for donation of four electrons. Detailed structural and spectroscopic characterization of three redox states (0, +2, and +4) reveal its unique electronic features. Despite its nitrogen richness, the compound is thermally robust and can be readily purified by sublimation.
- Eberle, Benjamin,Kaifer, Elisabeth,Himmel, Hans-J?rg
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supporting information
p. 3360 - 3363
(2017/03/17)
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- Condensation of vilsmeier salts, derived from tetraalkylureas, with α-hydroxy amide derivatives: One-pot approach to synthesize 2-dialkylamino-2-oxazolin-4-ones
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A novel and straightforward synthetic protocol was developed to synthesize 2-dialkylamino-2-oxazolin-4-ones from various Vilsmeier salts and α-hydroxy amides derivatives. Notably, thozalinone (3a), as a mild stimulant in tristimania and anorexic, could be synthesized simply and in a high yield using this methodology.
- Liu, Bengen,Su, Dongshan,Wei, Zhonglin,Cao, Jungang,Liang, Dapeng,Lin, Yingjie,Duan, Haifeng
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supporting information
p. 249 - 252
(2017/02/10)
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- ELECTRONIC DEVICE AND COMPOUND
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The invention relates to an electronic device comprising a compound having Formula (1): ABX (1), wherein A is a structural moiety that consists of at least two atoms and comprises a conjugated system of delocalized electrons, each B is independently selected from an imine functional group (la), wherein R1, R2, R3, R4 are independently selected from C1-C30 alkyl, C2-C30 alkenyl, C2-C3 alkinyl, C3-C30 cycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C7-C30 arylalkyl, C3-C30 heteroarylalkyl, the wave line represents a covalent bond to the imine nitrogen atom, G is in each group (la) independently selected from a quarternary carbon atom and from a cyclopropenylidene structural moiety, x is an integer equal one or higher, preferably equal two or higher, and the lone electron pair of the imine nitrogen atom and/or the pi-electrons of the imine double bond of at least one group B is conjugated with the conjugated system of delocalized electrons comprised in the structural moiety A, with the proviso that two or more of the substituents R1, R2, R3, R4 may be connected to form a ring that may contain also unsaturation and, if any of the substituents R1, R2, R3, R4 comprises two or more carbon atoms, up to one third of the overall count of the carbon atoms in the substituent or in any ring formed by two connected substituents can be replaced with heteroatoms independently selected from O, S, N and B as well as to an electrically semiconducting material and a compound for use in the electronic device.
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Page/Page column 16
(2016/01/25)
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- 3-Glucosylated 5-amino-1,2,4-oxadiazoles: Synthesis and evaluation as glycogen phosphorylase inhibitors
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Glycogen phosporylase (GP) is a promising target for the control of glycaemia. The design of inhibitors binding at the catalytic site has been accomplished through various families of glucose-based derivatives such as oxadiazoles. Further elaboration of t
- Donnier-Maréchal, Marion,Goyard, David,Folliard, Vincent,Docsa, Tibor,Gergely, Pal,Praly, Jean-Pierre,Vidal, Sébastien
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supporting information
p. 499 - 503
(2015/06/08)
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- Method of manufacturing imidoyl diazidosulfochloride compd. various compd. and manufacturing method of using the same
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PROBLEM TO BE SOLVED: To provide a new production method for synthesizing an imidoyl chloride compound dispensing with chlorination agents having poor handleability, to provide a method for producing various compounds in high yield and purity by using the imidoyl chloride compound, and to provide a method for isolating the imidoyl chloride compound in high efficiency and purity from a mixture of the imidoyl chloride compound and a phthalic anhydride compound.SOLUTION: The method for producing the imidoyl chloride compound comprises reaction of a specific amide compound with a specific phthaloyl chloride compound to produce a specific imidoyl chloride compound.
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Paragraph 0032
(2016/12/16)
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- Tetraguanidino-functionalized phenazine and fluorene dyes: Synthesis, optical properties and metal coordination
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In this work the first phenazine derivatives with guanidino substituents were prepared and their structural and electronic properties studied in detail. The guanidino groups decrease the HOMO-LUMO gap, massively increase the quantum yield for fluorescence and offer sites for metal coordination. The yellow-orange colored 2,3,7,8-tetraguanidino-substituted phenazine shows intense fluorescence. The wavelength of the fluorescence signal is strongly solvent dependent, covering a region from 515 nm in Et2O solution (with a record quantum yield of 0.39 in Et2O) to 640 nm in water. 2,3-Bisguanidino-substituted phenazine is less fluorescent (maximum quantum yield of 0.17 in THF), but exhibits extremely large Stokes shifts. In contrast, guanidino-functionalized fluorenes emit only very weakly. Subsequently, the influence of coordination on the electronic properties and especially the fluorescence of the phenazine system was analysed. Coordination first takes place at the guanidino groups, and leads to a blue shift of the luminescence signal as well as a massive decrease of the luminescence lifetime. Luminescence is almost quenched completely upon CuI coordination. On the other hand, in the case of ZnII coordination the fluorescence signal remains strong (quantum yield of 0.36 in CH3CN). In the case of strong zinc Lewis acids, an excess of metal compound leads to additional coordination at the phenazine N atoms. This is accompanied by significant red-shifts of the lowest-energy transition in the absorption and fluorescence spectra. Pentanuclear complexes with two phenazine units were isolated and structurally characterized, and further aggregation leads to chain polymers. This journal is
- Bindewald, Elvira,Lorenz, Roxana,Hübner, Olaf,Brox, Dominik,Herten, Dirk-Peter,Kaifer, Elisabeth,Himmel, Hans-J?rg
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p. 3467 - 3485
(2015/03/05)
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- Alkaline Chemical Stability of Polymerized Ionic Liquids with Various Cations
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The success of long-lasting low-cost (nonplatinum) alkaline fuel cells is dependent on the development of anion exchange membranes (electrolyte separator) with high alkaline chemical stability. In this study, a series of methacrylate-based polymerized ionic liquids (PILs) were synthesized with various covalently attached cations: butylimidazolium, butylmethylimidazolium, trimethylammonium, pentamethylguanidinium, butylpyrrolidinium, and trimethylphosphonium. The alkaline chemical stability of these PILs was examined in tandem with their analogous ionic salts: 1-butyl-3-methylimidizolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, tetramethylammonium chloride, benzyltrimethylammonium chloride, hexamethylguanidinium chloride, 1,1-butylmethylpyrrolidinium chloride, and tetramethylphosphonium chloride. The degradation mechanisms and extent of degradation were quantified using 1H NMR spectroscopy at various pHs (in D2O), and temperature. The PILs with imidazolium and pyrrolidinium cations showed enhanced chemical stability relative to the PILs with ammonium and phosphonium cations. Interestingly, direct correlations were not observed between the PILs and their analogous small molecule ionic salts; significant degradation was observed in imidazolium ionic salts, most notably at high temperature/high pH conditions, while the pyrrolidinium-, ammonium-, and phosphonium-based ionic salts showed no degradation under any of the conditions examined. Additionally, results on the imidazolium ionic salts showed that methyl substitution in the C2 position limited the ring-opening degradation reaction, whereas the PIL with the unsubstituted imidazolium actually showed higher chemical stability relative to its substituted PIL counterpart. Overall, the alkaline chemical stability of the PILs in this study showed no correlation to that of their analogous small molecule ionic salts, suggesting that alkaline chemical stability studies on small molecules may not provide a solid basis for evaluating alkaline stability in polymers, counter to the hypothesis in many previous studies.
- Meek, Kelly M.,Elabd, Yossef A.
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p. 7071 - 7084
(2015/10/28)
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- Synthesis and selected reactivity studies of a dissymmetric (phosphinoylmethylpyridine N-oxide) methylamine platform
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Efficient syntheses for the precursor molecules, 2-{6- [((diphenylphosphoryl)methyl)pyridin-2-yl]methyl}isoindoline-1,3-dione (2), 2-[(1,3-dioxoisoindolin-2-yl)methyl]-6-[(diphenylphosphoryl)methyl]pyridine 1-oxide (3), and their 6-[bis(2-(trifluoromethyl)phenyl)phosphoryl]methyl analogues are reported along with their transformations into the dissymmetric ligands, [(6-(aminomethyl)pyridin-2-yl)methyl]diphenylphosphine oxide (4), 2-(aminomethyl)-6-[(diphenylphosphoryl)methyl]pyridine 1-oxide (5) and 2-(aminomethyl)-6-{[bis(2-(trifluoromethyl)phenyl)phosphoryl]methyl}pyridine 1-oxide (5-F). Selected reactivity of the aminomethyl substituent of 4 and 5, as well as complexation reactions of several of the compounds with lanthanide(III) ions are described. Molecular structures of three uniquely different complexes, {Pr{2-[HC(O)N(H)CH2]-6-[Ph2P(O)CH2]C 5H3NO}(NO3)3(MeOH)}2, {Eu{2-[(Me2N)2CN(H+)CH2]-6-[Ph 2P(O)CH2]C5H3N(H) +}(NO3)4(OMe)} and {Er{2-[(C8H 4O2)NCH2]-6-[Ph2P(O)CH 2]C5H3N(O)}(NO3)3(MeOH)} ·(CH3)2CO, have been determined by single-crystal X-ray diffraction methods. The observed and computationally modeled structures that employ bidentate and tridentate ligand/metal interactions are compared. These results suggest further ligand modifications that should provide improved solvent extraction reagents. Copyright
- Ouizem, Sabrina,Pailloux, Sylvie L.,Ray, Alisha D.,Duesler, Eileen N.,Dickie, Diane A.,Paine, Robert T.,Hay, Benjamin P.
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p. 3132 - 3148
(2014/06/09)
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- A versatile tripodal Cu(I) reagent for C-N bond construction via nitrene-transfer chemistry: Catalytic perspectives and mechanistic insights on C-H aminations/amidinations and olefin aziridinations
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A CuI catalyst (1), supported by a framework of strongly basic guanidinato moieties, mediates nitrene-transfer from PhI=NR sources to a wide variety of aliphatic hydrocarbons (C-H amination or amidination in the presence of nitriles) and olefins (aziridination). Product profiles are consistent with a stepwise rather than concerted C-N bond formation. Mechanistic investigations with the aid of Hammett plots, kinetic isotope effects, labeled stereochemical probes, and radical traps and clocks allow us to conclude that carboradical intermediates play a major role and are generated by hydrogen-atom abstraction from substrate C-H bonds or initial nitrene-addition to one of the olefinic carbons. Subsequent processes include solvent-caged radical recombination to afford the major amination and aziridination products but also one-electron oxidation of diffusively free carboradicals to generate amidination products due to carbocation participation. Analyses of metal- and ligand-centered events by variable temperature electrospray mass spectrometry, cyclic voltammetry, and electron paramagnetic resonance spectroscopy, coupled with computational studies, indicate that an active, but still elusive, copper-nitrene (S = 1) intermediate initially abstracts a hydrogen atom from, or adds nitrene to, C-H and C=C bonds, respectively, followed by a spin flip and radical rebound to afford intra- and intermolecular C-N containing products.
- Bagchi, Vivek,Paraskevopoulou, Patrina,Das, Purak,Chi, Lingyu,Wang, Qiuwen,Choudhury, Amitava,Mathieson, Jennifer S.,Cronin, Leroy,Pardue, Daniel B.,Cundari, Thomas R.,Mitrikas, George,Sanakis, Yiannis,Stavropoulos, Pericles
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supporting information
p. 11362 - 11381
(2014/09/17)
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- A novel ionic liquid for Li ion batteries-uniting the advantages of guanidinium and piperidinium cations
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We report on the synthesis and the properties of N,N,N′,N′- tetramethyl-N′′,N′′-pentamethyleneguanidinium bis(trifluoromethylsulfonyl)imide (PipGuan-TFSI). The cation of this novel ionic liquid combines guanidinium and piperidinium structural elements. We tested it for its viscosity, ion conductivity, and also for its thermal and electrochemical stability. Furthermore, a 0.5 M solution of lithium TFSI in PipGuan-TFSI was tested as an electrolyte for Li-ion batteries. These experiments included cycles of Li deposition/dissolution on stainless steel and (de)intercalation into/from LiFePO4 electrodes. The tests involving LiFePO4 cathodes were performed at various C-rates and temperatures for a better quantitative comparison to other electrolyte systems. We discuss in how far PipGuan-TFSI successfully combines the advantages of guanidinium and piperidinium ionic liquids for battery electrolyte applications.
- Bucher, Nicolas,Hartung, Steffen,Arkhipova, Maria,Yu, Denis,Kratzer, Philipp,Maas, Gerhard,Srinivasan, Madhavi,Hoster, Harry E.
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p. 1996 - 2003
(2014/01/06)
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- Bisguanidines with biphenyl, binaphthyl, and bipyridyl cores: Proton-sponge properties and coordination chemistry
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Herein, we report on the synthesis, protonation, and coordination chemistry of chelating guanidine ligands with biphenyl, binaphthyl, and bipyridyl backbones. The ligands are shown to be proton sponges, and this protonation was studied experimentally and by using quantum-chemical calculations. Group 10 metal (Ni, Pd, and Pt) complexes with different metal/ligand ratios were synthesized. In the case of the bipyridyl systems, coordination occurs exclusively at the pyridine N atoms, as opposed to protonation. The spin-density distribution and the magnetism were evaluated for a series of paramagnetic NiII complexes with the aid of paramagnetic NMR spectroscopic studies in alliance with quantum-chemical calculations and magnetic (SQUID) measurements. Through direct delocalization from the singly occupied molecular orbitals (SOMOs), a significant amount of spin density is placed on the guanidinyl groups, and spin polarization also transports spin density onto the aromatic backbone. Showing some backbone: Bisguanidines with flexible biaryl backbones are proton sponges and ligands in a series of new mono- and dinuclear Group 10 metal complexes (see figure). The spin-density distribution in paramagnetic NiII complexes was studied by using NMR spectroscopy and quantum-chemical calculations. Copyright
- Maronna, Astrid,Huebner, Olaf,Enders, Markus,Kaifer, Elisabeth,Himmel, Hans-Joerg
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p. 8958 - 8977
(2013/07/25)
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- Condensation of Vilsmeier salts, derived from tetraalkylureas, with amidoximes: a novel approach to access N,N-dialkyl-1,2,4-oxadiazol-5-amines
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A novel approach, consendation of vilsmeier salts and amidoximes, to access N,N-dialkyl-1,2,4-oxadiazol-5-amines has been developed. By this approach, a broad range of N,N-dialkyl-1,2,4-oxadiazol-5-amines, including aromatic, heteroaromatic and alphatic s
- Su, Dongshan,Duan, Haifeng,Wei, Zhonglin,Cao, Jungang,Liang, Dapeng,Lin, Yingjie
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supporting information
p. 6959 - 6963
(2019/04/10)
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- Orthoamides and iminium salts LXXIV [1]. Reactions of N,N,N',N'- Tetramethyl-chloroformamidiniumChloride with metals
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N,N,N',N'-Tetramethyl-formamidinium chloride (2a) reacts with elemental sodium in various solvents to give N,N,N',N',N'',N''-hexamethyl-guanidinium chloride (4a). The reaction of 2a with potassium affords N,N,N',N',N'',N'',N''', N'''-octamethyl-oxamidinium dichloride (3a). From the reaction of 2a with magnesium in different solvents in general result mixtures of the salts 4a, 3a and N,N,N',N'-tetramethyl-formamidinium chloride (10a). The composition of these mixtures depends on the solvent and the reaction temperature. Similar results are obtained, when a zinc'copper couple is used instead of magnesium. Very likely from 2a and magnesium or zinc, respectively, organometallic intermediates 11, 12 are formed which could be trapped by aromatic aldehydes and phenylisocyanate. The salt 2a can be reductively coupled by a low-valent titanium reagent to give the oxamidinium salt 3a.
- Kantlehner, Willi,Aichholz, Reiner,Karl, Martin
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experimental part
p. 305 - 319
(2012/07/13)
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- New preparation method for Vilsmeier reagent and related imidoyl chlorides
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An environmentally benign and inexpensive preparation method is described of some imidoyl chlorides, including the Vilsmeier reagent (VR), by using phthaloyl dichloride. Synthetic applications were demonstrated using the isolated VR or VR prepared in situ for the transformation of acids to acid chlorides, alcohols to chlorides, and the formylation of dimethylaminobenzene.
- Kimura, Yoshikazu,Matsuura, Daisuke,Hanawa, Takeshi,Kobayashi, Yukimoto
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experimental part
p. 1116 - 1118
(2012/03/26)
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- Synthesis and characterization of chiral guanidines und guanidinium salts derived from 1-phenylethylamine
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The synthesis of two new chiral guanidines 5 and 12 and derived guanidinium salts 6, 11, 13 -15 with one and three N-(1-phenylethyl) substituents is described. In both cases, the well-precedented, reliable route via chloro-formamidines was taken. Since di
- Castiglia, Amelie,El Sehrawi, Hend M.,Orbegozo, Thomas,Spitzner, Dietrich,Claasen, Birgit,Frey, Wolfgang,Kantlehner, Willi,Jaeger, Volker
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scheme or table
p. 337 - 346
(2012/07/14)
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- Tuning the properties of redox-active guanidino-functionalized aromatic ligands by substitution: Experiment and theory
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Substitution of the aromatic hydrogen atoms in the electron donors 1,2,4,5-tetrakis(tetramethylguanidino)benzene (1a) and 1,2,4,5-tetrakis(N,N'- dimethyl-N,N'-ethyleneguanidino)benzene (1b) by iodide (to give 2a and 2b) and nitro groups (to give 3a and 3b
- Peters, Anastasia,Herrmann, Hendrik,Magg, Martin,Kaifer, Elisabeth,Himmel, Hans-Joerg
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experimental part
p. 1620 - 1631
(2012/06/04)
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- Redox-active guanidine ligands with pyridine and p-benzoquinone backbones
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Herein we report on the synthesis and some aspects of the chemistry of the new redox-active ligands 2,3,5,6-tetrakis(tetramethylguanidino)pyridine, 2,3,5,6-tetrakis(tetramethylguanidino)-p-benzoquinone and 2,3,5,6-tetrakis(N,N'- dimethyl-N,N'-ethyleneguanidino)-p-benzoquinone. All three ligands are strong electron donors. In addition, the p-benzoquinone systems feature low LUMO energies and small HOMO-LUMO gaps. A comparison of the ligands was made with regard to their optical properties, Bronsted basicity and electron-donor properties; results of quantum chemical calculations were included in this comparison. Subsequently, dinuclear copper complexes were prepared. Preliminary experiments on their redox chemistry followed. Copyright
- Stang, Simone,Lebkuecher, Anna,Walter, Petra,Kaifer, Elisabeth,Himmel, Hans-Joerg
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p. 4833 - 4845
(2013/01/15)
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- Synthesis and characterization of novel guanidine ligands featuring biphenyl or binaphthyl backbones
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In this paper we report on the synthesis and characterization of several new 2,2′-bisguanidino-1,1′-biphenyl and -binaphthyl ligands as well as the electron donor 3,3′,4,4′-tetrakis(tetramethylguanidino)-1, 1′-biphenyl. Chiral bisguanidine ligands were pr
- Maronna, Astrid,Bindewald, Elvira,Kaifer, Elisabeth,Wadepohl, Hubert,Himmel, Hans-Joerg
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experimental part
p. 1302 - 1314
(2011/06/10)
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- PEPTIDE ANALOGUES
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The present invention relates to compounds of Formula (I) and their pharmaceutically acceptable salts, wherein the substituents are as described herein, and their use in medicine, in particular as opioid agonists
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- Process of Making 2-Deoxy-2,2-Difluoro-D-Ribofuranosyl Nucleosides and Intermediates Therefor
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A compound of formula (A) or salt thereof: wherein each of R1, R2, and R3 independently represents hydrogen, alkyl, aryl, acyl, sulfonyl, or silyl; P represents hydrogen or a hydroxy protective group. This compound may be
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Page/Page column 6-7
(2010/04/23)
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- Novel hydroxide-conducting polyelectrolyte composed of an poly(arylene ether sulfone) containing pendant quaternary guanidinium groups for alkaline fuel cell applications
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Poly(arylene ether sulfone)s were functionalized with quaternary guanidinium groups in order to investigate their properties as novel polymeric hydroxide exchange membrane materials. The quaternized polymers were synthesized via chloromethylation of poly(
- Wang, Junhua,Li, Shenghai,Zhang, Suobo
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experimental part
p. 3890 - 3896
(2011/10/09)
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- A novel family of onium salts based upon isonitroso meldrum's acid proves useful as peptide coupling reagents
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A new family of uronium salts (HTMU, HMMU, and HDmPyMU) based on isonitroso Meldrum's acid (HONM) are reported as stand-alone coupling reagents. Amide bond formation with the use of these reagents occurred more quickly than that with other uronium salts as a result of the presence of a neighboring group effect with a cyclic structure. Thus, these novel onium salts were often more effective in the acylation of poor nucleophiles and in the control of optical purity than related Oxyma- and benzotriazole-based reagents. Among the HONM derivatives, HMMU showed the best performance in reducing racemization and assembling demanding sequences such as the Aib-ACP decapeptide or analogues of Leu-enkephalin pentapeptide, Furthermore, the scope and limitations of the use of HONM as an additive in combination with carbodiimides is discussed.
- El-Faham, Ayman,Subiros-Funosas, Ramon,Albericio, Fernando
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experimental part
p. 3641 - 3649
(2010/09/03)
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- Synthesis of 2-(4,6-Dimethoxy-1,3,5-triazin-2-yloxyimino) derivatives: Application in solution peptide synthesis
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A new class of 1,3,5-triazinyloxyimino derivatives were prepared, characterized and tested for reactivity in solution peptide synthesis. The new triazinyloxyimino derivatives failed to activate the carboxyl group during formation of peptide bonds, but gav
- Al-Warhi, Tarfah I.,AL-Hazimi, Hassan M.A.,El-Faham, Ayman,Albericio, Fernando
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scheme or table
p. 9403 - 9417
(2011/03/22)
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- Synthesis and crystal structures of N-[ω-(Dimethylammonio)alkyl]- N′,N′,N″,N″-tetramethylguanidinium chloride tetraphenylborates
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Dicationic N,N′,N′,N″,N″-pentasubstituted guanidinium dichlorides 4a, b are obtained from the chloroformamidinium salt 2 and diamines 3a, b. N-[2-(Dimethylammonio)ethyl]-N′,N′,N″, N″-tetramethylguanidinium chloride tetraphenylborate (5a) and N-[3-(dimethylammonio)propyl]-N′,N′,N″,N″- tetramethylguanidinium chloride tetraphenylborate (5b) were synthesized from 4a, b by anion metathesis with one equivalent of sodium tetraphenylborate. The thermal properties of the salts 5a, b were studied by means of DSC methods, and their crystal structures were determined by single-crystal X-ray diffraction analysis. For 5a a solid-solid phase transition is observed at 156 °C to a low-temperature structure. The room-temperature modification (α-5a) crystallizes in the centrosymmetric orthorhombic space group Pbca (a = 13.1844(4), b = 13.8007(4), c = 34.7537(11) A). The guanidinium ions are interconnected via chloride ions through bridging N-H...Cl hydrogen bonds, providing isolated units. The tetraphenylborate ions show some dynamic disordering in the crystal structure. The low-temperature modification (β-5a) also crystallizes orthorhombically, but in the non-centrosymmetric space group Pna21 (a = 13.1099(4), b = 69.1810(11), c = 13.5847(5) A) and consists of four crystallographically independent cations and anions in the unit cell. Compared with the room-temperature structure, a similar N-H...Cl hydrogen bond pattern is observed in the β-phase, but the tetraphenylborate ions are now completely ordered. 5b crystallizes in the monoclinic space group P21/c (a = 10.8010(3), b = 14.1502(5), c = 20.9867(9) A, β= 94.322(1)°). In the crystal structure the guanidinium ions are linked via chloride ions through N-H...Cl hydrogen bonds, but in contrast to 5a two infinite strands are formed along the a axis with the tetraphenylborate ions interspersed between them for charge compensation.
- Tiritiris, Ioannis,Lissner, Falk,Schleid, Thomas,Kantlehner, Willi
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scheme or table
p. 907 - 915
(2011/01/10)
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- Orthoamides, lxix [1]. Contributions to the synthesis of N,N,N′,N′,N″-peralkylated guanidines and N,N,N′, N′,N″,N″-persubstituted guanidinium salts
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N,N,N′,N′-Tetraalkyl-chloroformamidinium chlorides 6 are prepared from N,N,N′,N′-tetraalkylureas 5 and phosgene in acetonitrile. The iminium salts 6 react with primary and secondary amines in the presence of triethylamine to give N,N,N′,N′,N″- pentasubsti
- Kantlehner, Willi,Jochenmezger,Kre?, Ralf,Hartmann, Horst,Moschny, Thorsten,Tiritiris, Ioannis,Iliev, Boyan,Scherr, Oliver,Ziegler, Georg,Souley, Bahari,Frey, Wolfgang,Ivanov, Ivo C.,Bogdanov, Milen G.,J?ger, Ulrich,Dospil, Günther,Viefhaus, Tillmann
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experimental part
p. 873 - 906
(2011/01/08)
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- The catalytic potential of 4-guanidinylpyridines in acylation reactions
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A series of 3-alkyl-4-guanidinylpyridines with variable alkylation pattern have been synthesized and characterized with respect to their catalytic potential in acylation reactions of alcohols. The ability of the substitution pattern to stabilize acylpyridinium cations, which act as critical intermediates in the catalytic cycle of pyridine-catalyzed acylation reactions, has been assessed at the MP2(FC)/6-31+G(2d,p)//B98/6-31G(d) level of theory and inclusion of solvent effects in chloroform using the PCM continuum solvation model. The most active 4-guanidinylpyridines are among those having the most electron-rich pyridine ring. The influence of the type and concentration of the auxiliary base on the catalytic activity has also been studied. While the change from triethylamine to N,N-diisopropylethylamine as the auxiliary base does not lead to a systematic increase or decrease in the catalytic rates, the complete absence of auxiliary base leads to a 27-fold reduction in reaction rate. Georg Thieme Verlag Stuttgart.
- Held, Ingmar,Larionov, Evgeny,Bozler, Christian,Wagner, Felicia,Zipse, Hendrik
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experimental part
p. 2267 - 2277
(2009/12/31)
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- Synthesis of optically active α-amino ester derived pentasubstituted guanidines and hexasubstituted guanidinium salts as potential ionic liquids
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Tetrasubstituted urea derived chloroamidinium salts reacted with α-amino esters to give new chiral pentasubstituted guanidines. Further alkylation with methyl iodide provided hexasubstituted guanidinium salts, which represent new chiral room temperature i
- Shah, Jabbar,Liebscher, Juergen
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p. 917 - 920
(2008/09/21)
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- 1,2,4,5-Tetrakis(tetramethylguanidino)benzene: Synthesis and properties of a new molecular electron donor
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The molecular electron donor 1,2,4,5-tetrakis(tetramethylguanidino) benzene (ttmgb) was synthesised by reaction between 1,2,4,5-tetraaminobenzene and 2-chloro-1,1′,3,3′-tetramethylformamidinium chloride. Protonation and oxidation of the molecule were anal
- Peters, Anastasia,Kaifer, Elisabeth,Himmel, Hans-Joerg
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experimental part
p. 5907 - 5914
(2009/05/27)
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- Diaminocarbene- and Fischer-carbene complexes of palladium and nickel by oxidative insertion: Preparation, structure, and catalytic activity
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Oxidative insertion of [Pd(PPh3)4] or [Ni(cod) 2]/PPh3 into the C-Cl bond of various 2- chloroimidazolinium- and other -amidinium salts affords metal-diaminocarbene complexes in good to excellent yields. This procedure is complementary to existing methodology in which the central metal does not change its oxidation state, and therefore allows to incorporate carbene fragments that are difficult to access otherwise. The preparation of a variety of achiral as well as enantiomerically pure, chiral metal-NHC complexes (NHC = N-heterocyclic carbene) and metal complexes with acyclic diaminocarbene ligands illustrates this aspect. Furthermore it is shown that oxidative insertion also paves a way to prototype Fischer carbenes of PdII. Since the required starting materials are readily available from urea- or thiourea derivatives, this novel approach allows for substantial structural variations of the ligand backbone. The catalytic performance of the resulting library of nickel- and palladium-carbene complexes has been evaluated by applications to prototype Suzuki-, Heck-, and Kumada-Corriu cross-coupling reactions as well as Buchwald-Hartwig aminations. It was found that even Fischer carbenes show appreciable catalytic activity. Moreover, representative examples of all types of neutral and cationic metal-carbene complexes formed in this study have been characterized by X-ray crystallography.
- Kremzow, Doris,Seidel, Guenter,Lehmann, Christian W.,Fuerstner, Alois
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p. 1833 - 1853
(2007/10/03)
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- Synthesis of 2-dimethylaminobenzazoles via a guanidine intermediate: Reaction of 2-substituted aniline derivatives with 2-chloro-1,1,3,3-tetramethyl-formamidinium chloride
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Reactions of 2-aminophenols, 2-aminothiophenol and ophenylenediamines with 2-chloro-1,1,3,3-tetramethylformamidinium chloride proceeded easily via cyclization of guanidine intermediates to give the corresponding benzazoles having a dimethylamino group at
- Ohno, Kosei,Ishida, Wakako,Kamata, Kazuyuki,Oda, Kazuaki,Machida, Minoru
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p. 317 - 322
(2007/10/03)
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