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1.
Xing‐Chen Yan Yu‐Hua Fan Cai‐Feng Bi Xia Zhang Zhong‐Yu Zhang 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(1):61-65
The contributions of the amino and imino resonance forms to the ground‐state structures of 2‐amino‐4‐methylpyridinium nitrate, C6H9N2+·NO3−, and the previously reported 2‐amino‐5‐methylpyridinium nitrate [Yan, Fan, Bi, Zuo & Zhang (2012). Acta Cryst. E 68 , o2084], were studied using a combination of IR spectroscopy, X‐ray crystallography and density functional theory (DFT). The results show that the structures of 2‐amino‐4‐methylpyridine and 2‐amino‐5‐methylpyridine obtained upon protonation are best described as existing largely in the imino resonance forms. 相似文献
2.
Rafal Kruszynski Agata Trzesowska‐Kruszynska 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(9):o449-o454
In the title compounds, C7H6ClN2O+·NO3− and C7H6ClN2O+·ClO4−, the ions are connected by N—H...O hydrogen bonds and halogen interactions. Additionally, in the first compound, co‐operative π–π stacking and halogen...π interactions are observed. The energies of the observed interactions range from a value typical for very weak interactions (1.80 kJ mol−1) to one typical for mildly strong interactions (53.01 kJ mol−1). The iminium cations exist in an equilibrium form intermediate between exo‐ and endocyclic. This study provides structural insights relevant to the biochemical activity of 2‐amino‐5‐chloro‐1,3‐benzoxazole compounds. 相似文献
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Meiyappan Muthuraman Jean‐Franois Nicoud Muriel Bagieu‐Beucher 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1077-1078
The title compound, alternatively sodium pyridin‐2‐olate trihydrate, Na+·C5H3N2O3?·3H2O, crystallizes in the P space group. It is made up of edge‐shared chains of NaO6 octahedra with five water molecules and one 5‐nitro‐2‐pyridonate anion. Four of these water molecules are bicoordinating, involved in connecting the adjacent octahedra, and the fifth is coordinated to only one octahedron. The crystal structure is stabilized by a network of strong O—H?O and O—H?N interactions. The organic moieties occupy the space between the chains with an antiparallel alignment. 相似文献
6.
4‐Aminopyrazole‐3‐ones 4b, e, f were prepared from pyrazole‐3‐ones 1b‐d in a four‐step reaction sequence. Reaction of the latter with methyl p‐toluenesulfonate gave 1‐methylpyrazol‐3‐ones 2b‐d . Compounds 2b‐d were treated with aqueous nitric acid to give 4‐nitropyrazol‐3‐ones 3b‐d. Reduction of compounds 3b‐d by catalytic hydrogenation with Pd‐C afforded the 4‐amino compounds 4b, e, f. Using similar reaction conditions, nitropyrazole‐3‐ones derivatives 2c, d were reduced into aminopyrazole‐3‐ones 5e, f. 4‐Iodopyrazole‐3‐ones 7a, 7c and 8 were prepared from the corresponding pyrazol‐3‐ones 2a, 2c and 6 and iodine monochloride or sodium azide and iodine monochloride. 相似文献
7.
Vladimir N. Nesterov Elena A. Viltchinskaia 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):616-618
The structures of the title compounds, C15H13N3O4, (I), and C16H15N3O5 [IUPAC name: ethyl 6‐amino‐5‐cyano‐2‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyrano‐3‐carboxylate], (II), are very similar, with the heterocyclic rings adopting boat conformations. The pseudo‐axial m‐nitrophenyl substituents are rotated by 84.0 (1) and 98.7 (1)° in (I) and (II), respectively, with respect to the four coplanar atoms of the boat. The dihedral angles between the phenyl rings and nitro groups are 12.1 (2) and 8.4 (2)° in (I) and (II), respectively. The two compounds have similar patterns of intermolecular N—H?O and N—H?N hydrogen bonding, which link molecules into infinite tapes along b . 相似文献
8.
Lamine Hamdellou Olivier Hernandez Jean Meinnel 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o557-o560
The structures of 4‐dimethylamino‐β‐nitrostyrene (DANS), C10H12N2O2, and 4‐dimethylamino‐β‐ethyl‐β‐nitrostyrene (DAENS), C12H16N2O2, have been solved at T = 100 K. The structure solution for DANS was complicated by the presence of a static disorder, characterized by a misorientation of 17% of the molecules. The molecule of DANS is almost planar, indicating significant conjugation, with a push–pull effect through the styrene skeleton extending up to the terminal substituents and enhancing the dipole moment. As a consequence of this conjugation, the hexagonal ring displays a quinoidal character; the lengths of the C—N [1.3595 (15) Å] and C—C [1.448 (2) Å] bonds adjacent to the benzene ring are shorter than single bonds. The molecules are stacked in dimers with antiparallel dipoles. In contrast, the molecule of DAENS is not planar. The ethyl substituent pushes the nitropropene group out of the benzene plane, with a torsion angle of −21.9 (3). Nevertheless, the molecule remains conjugated, with a shortening of the same bonds as in DANS. 相似文献
9.
Vladimir N. Nesterov David J. Wiedenfeld Svitlana V. Nesterova Lucas F. Hastings 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o705-o708
The syntheses, X‐ray structural investigations and calculations of the conformational preferences of the carbonyl substituent with respect to the pyran ring have been carried out for the two title compounds, viz. C15H14N2O2, (II), and C20H16N2O2·C2H3N, (III), respectively. In both molecules, the heterocyclic ring adopts a flattened boat conformation. In (II), the carbonyl group and a double bond of the heterocyclic ring are syn, but in (III) they are anti. The carbonyl group forms a short contact with a methyl group H atom in (II). The dihedral angles between the pseudo‐axial phenyl substituent and the flat part of the pyran ring are 92.7 (1) and 93.2 (1)° in (II) and (III), respectively. In the crystal structure of (II), intermolecular N—H⋯N and N—H⋯O hydrogen bonds link the molecules into a sheet along the (103) plane, while in (III), they link the molecules into ribbons along the a axis. 相似文献
10.
Qian Zhao Han‐Geng Chen Chao Qian Xin‐Zhi Chen 《Journal of heterocyclic chemistry》2013,50(1):145-148
2‐Chloro‐3‐amino‐4‐methylpyridine ( 1 ), a key intermediate in the synthesis of nervirapine, was prepared from 2‐cyanoacetamide and 4,4‐dimethoxyl‐2‐butanone via condensation, cyclization, one‐pot reaction of chlorination and hydrolysis, and Hofmann reaction. Utilization of the quadratic orthogonal test resulted in a high yield (62.1%) of the whole process. 相似文献
11.
Tod J. Miller Yanwen Fu Frank R. Fronczek Robert P. Hammer 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e574-e575
The title compound, C18H19NO4, is the key synthetic intermediate in the preparation of α,α‐dibenzyl‐α‐amino acid (dibenzylglycine, Dbg), the disubstituted homologue of phenylalanine, following the dialkylation of ethyl nitroacetate. The molecule does not have its potential mirror symmetry in the crystal, with the two benzyl groups forming N—C—C—C torsion angles of 60.31 (13) and 79.89 (13)°. 相似文献
12.
Silvia E. Asías Ana M. Bruno Diego A. Dominici Mariela Bollini Carlos H. Gaozza 《Journal of heterocyclic chemistry》2003,40(1):107-112
In order to find new antimalarial drugs, an exploration about the chemical properties of the starting compounds 3‐amino‐6‐chloro‐4‐phenyl‐1H‐quinolin‐2‐one ( 1 ) and 3‐amino‐4‐methyl‐1H‐quinolin‐2‐one ( 2 ) was developed. Acylation with acyl chloride, sulfonyl chloride and acetic anhydride were carried out. Despite a previous report [2], when acetyl chloride or acetic anhydride were assayed on 1 , only the diacetyl derivative 7 was obtained. When this compound was heated at reflux temperature in a mixture of acetic acid and acetic anhydride, it was transformed in the oxazoloquinoline 8 . Further reactions of the acyl derivatives with diazomethane afforded 1‐methylated compounds. Compound 2 gave the imine 16 by condensation with 4‐nitrobenzaldehyde. 相似文献
13.
M. D. Crozet P. Vanelle M. Giorgi A. Gellis 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o496-o498
The title compounds, C13H15N3O5S and C11H10N2O4S2, respectively, both contain a phenylsulfonyl group connected, through a methylene bridge, to either a substituted nitroimidazole or nitro‐1,3‐thiazole ring. In the imidazole‐containing molecule, the nitro and sulfonyl groups are trans relative to the sulfonyl–methyl bond, while in the thiazole‐containing molecule, these substituents are cis. The stabilizing interactions within the crystals are also different between the two compounds. 相似文献
14.
Pawe Wagner Krzysztof
wierczek Maciej Kubicki 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(8):o445-o447
Infinite chains connected by N—H...N hydrogen bonding form the primary packing motif in two closely related 4‐nitroimidazole derivatives, viz. 5‐bromo‐2‐methyl‐4‐nitro‐1H‐imidazole, C4H4BrN3O2, (I), and 2‐methyl‐4‐nitro‐1H‐imidazole‐5‐carbonitrile, C5H4N4O2, (II). These chains are almost identical, even though in (II) there are two symmetry‐independent molecules in the asymmetric unit. The differences appear in the interactions between the chains; in (I), there are strong C—Br...O halogen bonds, which connect the chains into a two‐dimensional grid, while in (II), the cyano group does not participate in specific interactions and the chains are only loosely connected into a three‐dimensional structure. 相似文献
15.
Jairo Quiroga Jaime Portilla John N. Low Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(2):o76-o79
The molecules of 5‐amino‐1‐(4‐methoxybenzoyl)‐3‐methylpyrazole, C12H13N3O2, (I), and 5‐amino‐3‐methyl‐1‐(2‐nitrobenzoyl)pyrazole, C11H10N4O3, (II), both contain intramolecular N—H...O hydrogen bonds. The molecules of (I) are linked into a chain of rings by a combination of N—H...N and N—H...π(arene) hydrogen bonds, while those of (II) are linked into a three‐dimensional framework structure by N—H...N and C—H...O hydrogen bonds. 相似文献
16.
Matthew Polson Mark M. Turnbull Jan L. Wikaira 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(10):1152-1156
The hydrobromide and hydrochloride salts of 2‐amino‐5‐iodopyridine were prepared from aqueous solutions. The hydrobromide salt, C5H6IN2+·Br−·0.5H2O, crystallizes as a hemihydrate, and exhibits hydrogen bonding and π‐stacking which stabilize the crystal structure. The hydrochloride salt, C5H6IN2+·Cl−·H2O·0.375HCl, crystallized as the hydrate and exhibits similar hydrogen bonding and π‐stacking in the lattice. The most interesting feature of the hydrochloride salt is the presence of an additional fractional HCl molecule which introduces disorder in the location of the water molecule. The additional proton from the fractional HCl molecule is accounted for by the presence of a partial hydronium ion on one of the water sites. 相似文献
17.
Tamara I. Vakulskaya Lyudmila I. Larina Nadezhda I. Protsuk Valentin A. Lopyrev 《Magnetic resonance in chemistry : MRC》2009,47(9):716-719
The non‐degenerate tautomers of 3‐nitro‐1,2,4‐triazole‐5‐one (NTO) radical anions were investigated for the first time by an ESR method during electrochemical reduction of NTO in an aprotic medium. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
18.
Jzef Ryczek 《Journal of heterocyclic chemistry》2003,40(4):665-670
In the reaction of ethyl isothiocyanatoacetate with diamines, followed by cyclization of the intermediate product, 3‐monosubstituted thiohydantoins have been obtained. It was found that the reaction course depends on the purity of the isothiocyanate used and also, in the case of dialkylaminoamines, the self‐cyclization occurs. Besides the dialkylamino derivatives of 3‐monosubstituted 2‐thiohydantoins also new monoalkylamino, amino and heterocyclic derivatives were synthesized. The aryldiazonium derivative of 3‐monosubstituted 2‐thiohydantoin yielded both respective phenol derivative after hydrolysis and the product of coupling with 2‐naphthol. 相似文献
19.
Christopher Glidewell John N. Low Manuel Melguizo Antonio Quesada 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):o14-o18
In 2‐amino‐4,6‐dimethoxy‐5‐nitropyrimidine, C6H8N4O4, the molecules are linked by one N—H⋯N and one N—H⋯O hydrogen bond to form sheets built from alternating R(8) and R(32) rings. In isomeric 4‐amino‐2,6‐dimethoxy‐5‐nitropyrimidine, C6H8N4O4, which crystallizes with Z′ = 2 in P, the two independent molecules are linked into a dimer by two independent N—H⋯N hydrogen bonds. These dimers are linked into sheets by a combination of two‐centre C—H⋯O and three‐centre C—H⋯(O)2 hydrogen bonds, and the sheets are further linked by two independent aromatic π–π‐stacking interactions to form a three‐dimensional structure. 相似文献
20.
Svitlana V. Shishkina Irina S. Konovalova Sergiy M. Kovalenko Dmitriy V. Kravchenko Natalya D. Bunyatyan 《Acta Crystallographica. Section C, Structural Chemistry》2021,77(1):40-48
Being a close analogue of amflutizole, methyl 4‐amino‐3‐phenylisothiazole‐5‐carboxylate (C11H10N2O2S) was assumed to be capable of forming polymorphic structures. Noncentrosymmetric and centrosymmetric polymorphs have been obtained by crystallization from a series of more volatile solvents and from denser tetrachloromethane, respectively. Identical conformations of the molecule are found in both structures. The two polymorphs differ mainly in the intermolecular interactions formed by the amino group and in the type of stacking interactions between the π‐systems. The most effective method for revealing packing motifs in structures with intermolecular interactions of different types (hydrogen bonding, stacking, dispersion, etc.) is to study the pairwise interaction energies using quantum chemical calculations. Molecules form a column as the primary basic structural motif due to stacking interactions in both polymorphic structures under study. The character of a column (straight or zigzag) is determined by the orientations of the stacked molecules (in a `head‐to‐head' or `head‐to‐tail' manner). Columns bound by intermolecular N—H…O and N—H…N hydrogen bonds form a double column as the main structural motif in the noncentrosymmetric structure. Double columns in the noncentrosymmetric structure and columns in the centrosymmetric structure interact strongly within the ab crystallographic plane, forming a layer as a secondary basic structural motif. The noncentrosymmetric structure has a lower density and a lower (by 0.59 kJ mol?1) lattice energy, calculated using periodic calculations, compared to the centrosymmetric structure. 相似文献