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Monatshefte Für Chemie

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https://www.readbyqxmd.com/read/28203033/the-phase-transition-of-pb8f14i2
#1
Matthias Weil
ABSTRACT: The reversible phase transition of Pb8F14I2 is of continuous type and takes place at about 107 °C as monitored by temperature-dependent single crystal and powder X-ray diffraction measurements, optical microscopy, and differential scanning calorimetry. The low-temperature ferroelastic phase crystallizes in the orthorhombic crystal system (23 °C, Bmmb, Z = 2, a = 6.0699(6) Å, b = 6.0165(6) Å, c = 25.077(2) Å, 1487 structure factors, 41 parameter, R(F(2) ) = 0...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127102/fluorine-free-liquid-repellent-surfaces-made-from-ionic-liquid-infused-nanostructured-silicon
#2
Roland W Bittner, Katharina Bica, Helmuth Hoffmann
ABSTRACT: Liquid-repellent surfaces based on slippery liquid-infused porous substrates (SLIPS) were prepared from porous, nanostructured silicon surfaces with different surface functionalization, infused with the polar ionic liquid 1-ethyl-3-methylimidazolium methylsulfate ([C2mim]MeSO4). Contrary to nonpolar SLIPS based on perfluorinated substrates and infusion liquids, [C2mim]MeSO4 forms stable SLIPS with high energy surfaces like native silicon (Si-SiO2) or ionic liquid-functionalized silicon (Si-[C3mim]Cl), whose liquid-repellent properties against low surface tension liquids (toluene, cyclohexane) were demonstrated by very low sliding angles (α < 3°) and low contact angle hysteresis (Δθ < 10°)...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127101/first-chemo-enzymatic-synthesis-of-the-r-taniguchi-lactone-and-substrate-profiles-of-camo-and-otemo-two-new-baeyer-villiger-monooxygenases
#3
Florian Rudroff, Michael J Fink, Ramana Pydi, Uwe T Bornscheuer, Marko D Mihovilovic
ABSTRACT: This study investigates the substrate profile of cycloalkanone monooxygenase and 2-oxo-Δ(3)-4,5,5-trimethylcyclopentenylacetyl-coenzyme A monooxygenase, two recently discovered enzymes of the Baeyer-Villiger monooxygenase family, used as whole-cell biocatalysts. Biooxidations of a diverse set of ketones were performed on analytical scale: desymmetrization of substituted prochiral cyclobutanones and cyclohexanones, regiodivergent oxidation of terpenones and bicyclic ketones, as well as kinetic resolution of racemic cycloketones...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127100/the-synthesis-of-15-n-7-hoogsteen-face-labeled-adenosine-phosphoramidite-for-solid-phase-rna-synthesis
#4
Sandro Neuner, Christoph Kreutz, Ronald Micura
ABSTRACT: We have developed an efficient route for the synthesis of (15)N(7)-labeled adenosine as phosphoramidite building block for site- and atom-specific incorporation into RNA by automated solid-phase synthesis. Such labeled RNA is required for the evaluation of selected non-canonical base pair interactions in folded RNA using NMR spectroscopic methods. GRAPHICAL ABSTRACT: HASH(0x41d1500)
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127099/microwave-alkylation-of-lithium-tetrazolate
#5
Danny Müller, Christian Knoll, Peter Weinberger
ABSTRACT: N1-substituted tetrazoles are interesting ligands in transition metal coordination chemistry, especially in the field of spin crossover. Their synthesis is performed in most cases according to the Franke-synthesis, using a primary amine as reagent introducing the substitution pattern. To enhance flexibility in means of substrate scope, we developed a new protocol based on alkylation of lithium tetrazolate with alkyl bromides. The N1-N2 isomerism of the tetrazole during the alkylation was successfully suppressed by use of highly pure lithium tetrazolate and 30 vol...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127098/synthesis-and-characterization-of-naphthalimide-functionalized-polynorbornenes
#6
Manuel Hollauf, Merima Cajlakovič, Martin Tscherner, Stefan Köstler, Astrid-Caroline Knall, Gregor Trimmel
ABSTRACT: Highly fluorescent and photostable (2-alkyl)-1H-benzo[de]isoquinoline-1,3(2H)-diones with a polymerizable norbornene scaffold have been synthesized and polymerized using ring-opening metathesis polymerization. The monomers presented herein could be polymerized in a living fashion, using different comonomers and different monomer ratios. All obtained materials showed good film-forming properties and bright fluorescence caused by the incorporated push-pull chromophores. Additionally, one of the monomers containing a methylpiperazine functionality showed protonation-dependent photoinduced electron transfer which opens up interesting applications for logic gates and sensing...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127097/synthesis-of-3-o-and-4-o-2-aminoethylphosphono-derivatives-of-methyl-l-glycero-%C3%AE-d-manno-heptopyranoside
#7
Martin Walter, Claudia Kohout, Markus Blaukopf, Paul Kosma
ABSTRACT: Phosphoethanolamine derivatives of the bacterial saccharide l-glycero-d-manno-heptose have been prepared using a phosphoramidite-based coupling reaction at position 4 of a side-chain-protected 2,3-O-orthoester methyl heptoside and at position 3 of a 3,4-diol heptoside, respectively. Global deprotection afforded the corresponding 2-aminoethylphosphodiester derivatives as substrates for crystallographic and binding studies with lectins and antibodies targeting the inner core structure of bacterial lipopolysaccharides...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127096/a-triazine-based-ni-ii-pnp-pincer-complex-as-catalyst-for-kumada-corriu-and-negishi-cross-coupling-reactions
#8
Mathias Mastalir, Karl Kirchner
ABSTRACT: Kumada-Corriu and Negishi cross-coupling reactions, catalyzed efficiently by a Ni(II) PNP pincer complex containing a triazine backbone, are described. The catalyst is able to react with both activated and inactivated aryl halides including chlorides as well as phenol derivatives such as tosylates and mesylates to give the corresponding cross-coupling products in good to excellent isolated yields. A high diversity of substrates was tested under moderate conditions for both types of reactions...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127095/improved-simplicity-and-practicability-in-copper-catalyzed-alkynylation-of-tetrahydroisoquinoline
#9
Birgit Gröll, Patricia Schaaf, Michael Schnürch
ABSTRACT: Alkynylation reactions of N-protected tetrahydroisoquinolines have been performed using several different protocols of cross dehydrogenative coupling. Initially, a CuCl-catalyzed method was investigated, which worked well with three different N-protecting groups, namely phenyl, PMP, and benzyl and t-BuOOH as oxidant in acetonitrile as solvent. The peroxide could then be replaced by simple air and acetonitrile for water, leading to an overall very environmentally friendly protocol...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127094/efficient-preparation-of-2-nitroimidazole-nucleosides-as-precursors-for-hypoxia-pet-tracers
#10
Petra Križková, Anna Wieczorek, Friedrich Hammerschmidt
ABSTRACT: 2-Deoxy-D-ribose was converted to α/β-mixtures of methyl 3-O-acetyl- and methyl 3-O-benzoyl-2-deoxy-5-(p-toluenesulfonyl)-D-ribofuranosides. These were reacted with boron trichloride to generate ribofuranosyl chlorides, which afforded precursors for tracers to image tumor hypoxia on substitution with salts of 2-nitroimidazole. The anomeric ratio of the nucleosides was delicately influenced by the reaction conditions. GRAPHICAL ABSTRACT: HASH(0x32c89c8) ...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127093/on-the-origin-of-the-stereoselectivity-in-chiral-amide-based-ammonium-ylide-mediated-epoxidations
#11
Johanna Novacek, Raphaël Robiette, Mario Waser
ABSTRACT: Detailed DFT studies provide an in-depth mechanistic understanding for the use of chiral amide-based ammonium ylides in epoxidation reactions. It is shown that the used chiral auxiliary efficiently shields one face of the ylide, which thus results in an extraordinarily high stereoselectivity giving only one trans-isomer with perfect control of the absolute configuration. GRAPHICAL ABSTRACT: HASH(0x3477498)
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127092/a-simplified-and-scalable-synthesis-of-artesunate
#12
Armin Presser, Andrea Feichtinger, Silke Buzzi
ABSTRACT: An efficient and economically viable approach for the large-scale conversion of artemisinin into the antimalarial frontline drug artesunate was developed. This advanced synthesis includes an NaBH4-induced reduction, followed by an esterification with succinic anhydride under basic conditions. The entire conversion follows the principles of green chemistry, i.e., application of reusable solvents. GRAPHICAL ABSTRACT: HASH(0x41e4818)
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127091/synthesis-of-%C3%AE-pyrones-via-decarboxylative-condensation-of-%C3%AE-ketoacids
#13
Jérémy Merad, Thomas Maier, Catarina A B Rodrigues, Nuno Maulide
ABSTRACT: This manuscript describes the convergent synthesis of aryl- and alkyl-disubstituted γ-pyrones from β-ketoacids. The reaction proceeds in the presence of trifluoromethanesulfonic anhydride via an unprecedented decarboxylative auto-condensation of the starting material. Herein, the scope and limitations of this transformation are reported. GRAPHICAL ABSTRACT: HASH(0x347bed0)
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127090/recent-advancements-on-the-use-of-2-methyltetrahydrofuran-in-organometallic-chemistry
#14
REVIEW
Serena Monticelli, Laura Castoldi, Irene Murgia, Raffaele Senatore, Eugenia Mazzeo, Judith Wackerlig, Ernst Urban, Thierry Langer, Vittorio Pace
ABSTRACT: Since the introduction of 2-methyltetrahydrofuran as an useful alternative to the classical tetrahydrofuran, there has been a continuous interest in the synthetic community operating at academic and industrial towards it. In particular, the much higher stability that basic organometallic reagents display in 2-methyltetrahydrofuran makes it suitable for processes involving such sensitive species including asymmetric transformations. The easy formation of an azeotropic mixture with water, the substantial immiscibility with water, and the fact it derives from natural sources (corncobs or bagasse), allow to consider it in agreement with the Anastas' Geen Chemistry principles...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127089/sequential-and-iterative-pd-catalyzed-cross-coupling-reactions-in-organic-synthesis
#15
REVIEW
Patrick Dobrounig, Melanie Trobe, Rolf Breinbauer
ABSTRACT: Sequential and iterative Pd-catalyzed cross-coupling reactions can be performed in which the order of C-C bond formations can be controlled either by the attenuated leaving groups of the multireactive substrate or by specific catalyst/ligand combinations. This tutorial review gives an overview about recent developments in this field and the various strategies used for the assembly of oligoarenes and -alkenes. GRAPHICAL ABSTRACT: HASH(0x34bf1c8)
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/27881885/acyclic-nucleoside-phosphonates-containing-the-amide-bond
#16
Iwona E Głowacka, Dorota G Piotrowska, Graciela Andrei, Dominique Schols, Robert Snoeck, Andrzej E Wróblewski
ABSTRACT: To study the influence of a linker rigidity and donor-acceptor properties, the P-CH2-O-CHR- fragment in acyclic nucleoside phosphonates (e.g., acyclovir, tenofovir) was replaced by the P-CH2-HN-C(O)- residue. The respective phosphonates were synthesized in good yields by coupling the straight chain of ω-aminophosphonates and nucleobase-derived acetic acids with EDC. Based on the (1)H and (13)C NMR data, the unrestricted rotation within the methylene and 1,2-ethylidene linkers in phosphonates from series a and b was confirmed...
2016: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/27795584/copper-ii-complexes-with-imino-phenoxide-ligands-synthesis-characterization-and-their-application-as-catalysts-for-the-ring-opening-polymerization-of-rac-lactide
#17
Mrinmay Mandal, Kerstin Oppelt, Manuela List, Ian Teasdale, Debashis Chakraborty, Uwe Monkowius
ABSTRACT: Four new copper complexes based on bidentate imino phenoxide ligands were synthesized and characterized by IR, UV-Vis spectroscopy, ESI mass spectrometry, single crystal X-ray diffraction, and electrochemistry. The crystal structures revealed that the copper(II) atoms are surrounded by phenolate oxygen and imine nitrogen atoms of two ligands in a distorted square-planar geometry. The existence of ligand-centered, as well as Cu(II)-centered quasi-reversible and reversible redox reactions are observed in the cyclic voltammetry experiments of all the complexes...
2016: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/27795583/synthesis-characterization-and-antioxidant-activity-of-zn-2-and-cu-2-coordinated-polyhydroxychalcone-complexes
#18
Chiara Sulpizio, Simon T R Müller, Qi Zhang, Lothar Brecker, Annette Rompel
ABSTRACT: Four new metal complexes [Cu(ISO)2], [Cu(BUT)2] and [Zn(ISO)2], [Zn(BUT)2] of the polyhydroxychalcones (isoliquiritigenin and butein) are synthesized, structurally characterized and their antioxidant activity is investigated. The formation of the complexes [Cu(ISO)2] and [Zn(ISO)2] is followed by Job's plot using NMR titration. The resulting compounds are characterized by mass spectrometry, IR spectroscopy, and elemental analysis. Studies on the radical scavenging activity are performed using DPPH as substrate...
2016: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/27729714/synthesis-of-polybrominated-benzimidazole-and-benzotriazole-derivatives-containing-a-tetrazole-ring-and-their-cytotoxic-activity
#19
Edyta Łukowska-Chojnacka, Patrycja Wińska, Monika Wielechowska, Maria Bretner
ABSTRACT: A series of new benzimidazole and benzotriazole derivatives containing a tetrazole moiety was synthesized by N-alkylation of 5-aryltetrazole with 4,5,6,7-tetrabromo-1-(3-chloropropyl)-1H-benzimidazole and 4,5,6,7-tetrabromo-2-(3-chloropropyl)-2H-benzotriazole. The reaction was regioselective and mostly 2,5-disubstituted tetrazole derivatives were obtained. The effect of all synthesized compounds on human recombinant casein kinase 2alpha subunit (rhCK2α) and cytotoxicity against human T-cell lymphoblast (CCRF-CEM) and breast adenocarcinoma (MCF-7) cell lines were evaluated...
2016: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/27729713/synthesis-structure-and-antioxidant-activity-of-methoxy-and-hydroxyl-substituted-2-aminochalcones
#20
Chiara Sulpizio, Alexander Roller, Gerald Giester, Annette Rompel
ABSTRACT: Three 2'-aminochalcone derivatives (E)-1-(2-aminophenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, (E)-1-(2-aminophenyl)-3-(3,4-dihydroxyphenyl)prop-2-en-1-one, and (E)-1-(2-amino-4,5-dimethoxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one, have been synthesized, characterized, and tested in vitro in order to assess their antioxidant activity. All compounds were characterized on the basis of (1)H NMR, (13)C NMR, ESI-mass spectrometry, FT-IR, UV/Vis, and elemental analysis. The X-ray crystal structures of (E)-1-(2-aminophenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one and (E)-1-(2-amino-4,5-dimethoxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one were successfully determined showing a planar molecule geometry...
2016: Monatshefte Für Chemie
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