共查询到20条相似文献,搜索用时 46 毫秒
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N. Kodiah Beyeh Altti Ala‐Korpi Mario Cetina Arto Valkonen Kari Rissanen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15144-15150
N‐Alkyl ammonium resorcinarene chlorides are stabilized by an intricate array of intra‐ and intermolecular hydrogen bonds that leads to cavitand‐like structures. Depending on the upper‐rim substituents, self‐inclusion was observed in solution and in the solid state. The self‐inclusion can be disrupted at higher temperatures, whereas in the presence of small guests the self‐included dimers spontaneously reorganize to 1:1 host–guest complexes. These host compounds show an interesting ability to bind a series of N‐alkyl acetamide guests through intermolecular hydrogen bonds involving the carbonyl oxygen (C?O) atoms and the amide (NH) groups of the guests, the chloride anions (Cl?) and ammonium (NH2+) cations of the hosts, and also through CH ??? π interactions between the hosts and guests. The self‐included and host–guest complexes were studied by single‐crystal X‐ray diffraction, NMR titration, and mass spectrometry. 相似文献
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NMR spectra of a series of N‐arylsuccinanilic acids, N‐arylsuccinimides, N‐arylmaleanilic acids, and N‐arylmaleimides were examined to estimate the electronic effect of the amide and imide groups on the chemical shifts of the hydrogen and carbon nuclei of the benzene ring. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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A straightforward synthesis of N‐tosylhomosphinganine and N‐tosylsedridine has been achieved from trans‐4‐hydroxyproline by Grignard addition, regioselective Baeyer‐Villiger reaction, cross or ring‐closing metathesis and hydrogenation as the key steps. 相似文献
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Thien Y Vu Prof. Anna Chrostowska Prof. Thi Kieu Xuan Huynh Prof. Saïd Khayar Prof. Alain Dargelos Katarzyna Justyna Dr. Beata Pasternak Prof. Stanisław Leśniak Prof. Curt Wentrup 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14983-14988
Thermal reactions of N‐benzylidene‐ and N‐(2‐pyridylmethylidene)‐tert‐butylamines ( 5 and 13 ) under FVT conditions have been investigated. Unexpectedly, at 800 °C, compound 5 yields 1,2‐dimethylindole and 3‐methylisoquinoline. In the reaction of 13 at 800 °C, 3‐methylimidazo[1,5‐a]pyridine was obtained as the major product. Mechanisms of these reactions have been proposed on the basis of DFT calculations. Furthermore, UV‐photoelectron spectroscopy combined with FVT has been applied for direct monitoring and characterization of the thermolysis products in situ. 相似文献
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Niklas Gangloff Corinna Fetsch Robert Luxenhofer 《Macromolecular rapid communications》2013,34(12):997-1001
The nucleophilic living ring‐opening polymerization of N‐substituted glycine N‐carboxyanhydrides using solid‐phase synthesis resins is reported. By variation of experimental parameters, products with near Poisson distributions are obtained. As opposed to reversible deactivation radical polymerization, the living polymerization is demonstrated to be viable to high monomer conversion and through multiple monomer addition steps. Successful preparation of a multiblock copolypeptoid is proof for a highly living and robust character of the solid‐phase peptoid polymerization.
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The preparations of 4‐ and 5‐nitro‐1‐vinylimidazole ( 2 and 7 ) are described. Selective reduction of the nitro group using Fe/dil.HCl is achieved for the 4‐nitro derivative but this is not effective when ethoxymethylenemalononitrile is used to trap the amine. For 5‐nitroimidazole studies the N‐vinyl substituent is kept masked as a 2‐chloroethyl group, which remains unchanged during catalytic reduction of the nitro function (Pd/C), and is revealed by HCl elimination at a later stage. In this way, the 1‐deazapurine 13 and the tricyclic derivative 14 have been prepared. 相似文献
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Iain Coldham Prof. Sophie Raimbault Dr. David T. E. Whittaker Dr. Praful T. Chovatia Dr. Daniele Leonori Jignesh J. Patel Dr. Nadeem S. Sheikh Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(13):4082-4090
Proton abstraction of N‐tert‐butoxycarbonyl‐piperidine (N‐Boc‐piperidine) with sBuLi and TMEDA provides a racemic organolithium that can be resolved using a chiral ligand. The enantiomeric organolithiums can interconvert so that a dynamic resolution occurs. Two mechanisms for promoting enantioselectivity in the products are possible. Slow addition of an electrophile such as trimethylsilyl chloride allows dynamic resolution under kinetic control (DKR). This process occurs with high enantioselectivity and is successful by catalysis with substoichiometric chiral ligand (catalytic dynamic kinetic resolution). Alternatively, the two enantiomers of this organolithium can be resolved under thermodynamic control with good enantioselectivity (dynamic thermodynamic resolution, DTR). The best ligands found are based on chiral diamino‐alkoxides. Using DTR, a variety of electrophiles can be used to provide an asymmetric synthesis of enantiomerically enriched 2‐substituted piperidines, including (after Boc deprotection) the alkaloid (+)‐β‐conhydrine. The chemistry was extended, albeit with lower yields, to the corresponding 2‐substituted seven‐membered azepine ring derivatives. 相似文献
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N‐tert‐Butyl‐N‐benzoylhydrazine was prepared in a new and convenient procedure with good yield. Triphosgene underwent reaction with three equivalents of N‐t‐butyl‐N‐benzoylhydrazine using six equivalents of triethylamine as a base to yield the cyclic tetramer of N‐t‐butyl‐N‐isocyanatobenzoylamide. Treatment of triphosgene with three equivalents of N‐t‐butyl‐N‐benzoylhydrazine either in the presence of three equivalents of triethylamine or in the absence of triethylamine afforded the cyclic pentamer of iso‐cyanate, from which tert‐butyl is eliminated. 相似文献
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Uwe H. F. Bunz Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(28):6780-6789
The synthesis and the property evaluation of several large N‐heteroacenes are discussed. Issues of stability and aromaticity are compared and investigated and a historical perspective of the field is given. Some of the larger heterocyclic materials that are evaluated in this concept article have been around for more than one hundred years, yet their chemistry and properties are not well known/understood. 相似文献
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Adrin Turjanski Zulema Dbora Chaia Fabio Doctorovich Dario Estrin Ruth Rosenstein Oscar E. Piro 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):682-683
The title compound, N‐[2‐(5‐methoxy‐1‐nitroso‐1H‐indol‐3‐yl)ethyl]acetamide, C13H15N3O3, an N‐nitroso derivative of melatonin, crystallizes in the monoclinic C2/c space group. The molecules are arranged in such a way that the aromatic rings are in a planar conformation, with the alkylamide side chains in a different plane, at a dihedral angle of 108.60 (6)°. The alkylamide chains are interconnected by hydrogen bonds, constituting an infinite array. 相似文献
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Ligia R. Gomes John Nicolson Low Ana S. M. C. Rodrigues James L. Wardell Camillo H. da Silva Lima Marcus V. N. de Souza 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(5):549-555
The compounds N′‐benzylidene‐N‐methylpyrazine‐2‐carbohydrazide, C13H12N4O, (IIa), N′‐(2‐methoxybenzylidene)‐N‐methylpyrazine‐2‐carbohydrazide, C14H14N4O2, (IIb), N′‐(4‐cyanobenzylidene)‐N‐methylpyrazine‐2‐carbohydrazide dihydrate, C14H11N5O·2H2O, (IIc), N‐methyl‐N′‐(2‐nitrobenzylidene)pyrazine‐2‐carbohydrazide, C13H11N5O3, (IId), and N‐methyl‐N′‐(4‐nitrobenzylidene)pyrazine‐2‐carbohydrazide, C13H11N5O3, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55–78°. These methylated pyrazine‐2‐carbohydrazides have supramolecular structures which are formed by weak C—H...O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π–π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0–6°. 相似文献
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Hiroyuki Hosomi Shigeru Ohba Yoshikatsu Ito 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e144-e146
In the title four compounds, C13H11N·C7H4N2O6, (I), C15H15N·C7H4N2O6, (II), C16H17N·C7H4N2O6, (III), and C16H17N·C7H4N2O6, (IV), the donor and acceptor molecules are stacked alternately to form one‐dimensional columns. In (I), the N‐methyl group of the donor is nearly eclipsed with respect to one of the nitro groups of the neighboring acceptor in a column, whereas the N‐isopropyl, N‐butyl and N‐isobutyl groups are in anti positions with respect to one of the nitro groups of the neighboring acceptor in compounds (II)–(IV). 相似文献
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Andrey A. Kirilchuk Aleksandr A. Yurchenko Aleksandr N. Kostyuk Alexander B. Rozhenko 《Journal of computational chemistry》2015,36(1):42-48
1,2‐Migration of the phosphano‐group to the carbene center in N‐phosphano functionalized N‐heterocyclic carbenes has been studied by density functional theory (DFT) calculations. An intramolecular mechanism with a three‐center transition state structure seems to be most plausible for the isolated carbenes, while an intermolecular pathway catalyzed by azolium salts may be preferable for a migration proceeding in the course of generating the carbenes in situ. Our calculations show that amino‐substitution at the phosphorus atom and an enhanced nucleophilicity of the heterocycle scaffold facilitate the phosphorus shift. Calculated singlet‐triplet energy gaps do not correlate with thermodynamic stability of the studied carbenes and their disposition toward the 1,2‐rearrangement. © 2014 Wiley Periodicals, Inc. 相似文献
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Pawe Wagner Sabina Niemczyk‐Baltro Maciej Kubicki 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o83-o84
In the title compound, C8H8N2OS, strong intramolecular N—H⋯O hydrogen bonds [N⋯O = 2.669 (3) and 2.618 (3) Å] form almost planar six‐membered rings and enforce the conformation of the molecule. Two kinds of intermolecular N—H⋯S hydrogen bonds [N⋯S = 3.309 (3)–3.456 (2) Å] between two symmetry‐independent molecules form consecutive dimers that expand in ribbons along the [100] direction. 相似文献