共查询到20条相似文献,搜索用时 15 毫秒
1.
James L. Balderson Manuel A. Fernandes Joseph P. Michael Christopher B. Perry 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(12):o734-o738
The title compounds, namely (2Z)‐1‐(4‐bromophenyl)‐2‐(pyrrolidin‐2‐ylidene)ethanone, C12H12BrNO, (I), (2Z)‐1‐(4‐bromophenyl)‐2‐(piperidin‐2‐ylidene)ethanone, C13H14BrNO, (II), and (2Z)‐2‐(azepan‐2‐ylidene)‐1‐(4‐bromophenyl)ethanone, C14H16BrNO, (III), are characterized by bifurcated intra‐ and intermolecular hydrogen bonding between the secondary amine and carbonyl groups. The former establishes a six‐membered hydrogen‐bonded ring, while the latter leads to the formation of centrosymmetric dimers. Weak C—H...Br interactions link the individual molecules into chains that run along the [011], [101] and [101] directions in (I)–(III), respectively. Additional weak Br...O, C—H...π and C—H...O interactions further stabilize the crystal structures. 相似文献
2.
Juana E. Prez‐Vargas Francisco J. Martínez‐Martínez Itzia I. Padilla‐Martínez Herbert Hpfl Efrn V. García‐Bez 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):o517-o519
The title compound, C16H19NO5, crystallizes as a centrosymmetric dimer through strong O—H⋯O hydrogen‐bonding interactions between the hydroxyphenyl and morpholinocarbonyl groups. The morpholinocarbonyl group is almost perpendicular to the propenoate moiety. Electron delocalization in the N—C(=O) fragment leads to the formation of hydrogen‐bonded S(5) ring motifs through C—H⋯O interactions. 相似文献
3.
Vijayakumar N. Sonar Sean Parkin Peter A. Crooks 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(12):o743-o745
The title compounds, C20H17NO3S, (I), and C19H15NO2S, (II), were prepared by the reaction of benzo[b]thiophene‐2‐carbaldehyde with (3,4,5‐trimethoxyphenyl)acetonitrile and (3,4‐dimethoxyphenyl)acetonitrile, respectively, in the presence of methanolic potassium hydroxide. In (I), the C=C bond linking the benzo[b]thiophene and the 3,4,5‐trimethoxyphenyl units has E geometry, with dihedral angles between the plane of the bridging unit and the planes of the two adjacent ring systems of 5.2 (3) and 13.1 (2)°, respectively. However, in (II), the C=C bond has Z geometry, with dihedral angles between the plane of the bridging unit and the planes of the adjacent benzo[b]thiophene and 3,4‐dimethoxyphenyl units of 4.84 (17) and 76.09 (7)°, respectively. There are no significant intermolecular hydrogen‐bonding interactions in the packing of (I) and (II). The packing is essentially stabilized via van der Waals forces. 相似文献
4.
K. Sethu Sankar S. Kannadasan D. Velmurugan P. C. Srinivasan S. Shanmuga Sundara Raj H.‐K. Fun 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o277-o279
The title compound, C28H27N3O4S, crystallizes in the centrosymmetric space group P21/n, with one molecule in the asymmetric unit. In the indole ring, the dihedral angle between the fused rings is 3.6 (1)°. The phenyl ring of the sulfonyl substituent makes a dihedral angle of 79.2 (1)° with the best plane of the indole moiety. The phenyl ring of the dimethylaminophenyl group is orthogonal to the phenyl ring of the phenylsulfonyl group. The dihedral angle formed by the weighted least‐squares planes through the pyrrole ring and the phenyl ring of the dimethylaminophenyl group is 7.8 (1)°. The molecular structure is stabilized by C—H?O and C—H?N interactions. 相似文献
5.
Franois Loiseau Reinhard Neier Gaël Labat Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):o636-o638
In the title compound, C9H12Br2O3, a (tetrahydrofuran‐2‐ylidene)acetate, the double bond has the Z form. In the tetrahydrofuran group, the relative configuration of the Br atom in the 3‐position and the methyl group in the 5‐position is anti. The compound crystallizes with two independent molecules per asymmetric unit and, in the crystal structure, the individual molecules are linked to their symmetry‐equivalent molecules by C—H⋯O hydrogen bonds, so forming centrosymmetric hydrogen‐bonded dimers. 相似文献
6.
Synthesis of Polysubstituted Benzenes via the Vinylogous Michael Addition of Alkylidenemalononitriles to 2‐(1,3‐Dioxo‐1H‐inden‐2(3H)‐ylidene)malononitrile 下载免费PDF全文
Abdolali Alizadeh Hadi Sedighian Seyed Yasub Hosseini Long‐Guan Zhu 《Helvetica chimica acta》2015,98(4):569-574
An efficient synthesis for polysubstituted benzenes was successfully developed by the reaction of ninhydrin (=2,2‐dihydroxyindane‐1,3‐dione), malononitrile (=propanedinitrile), and alkylidenemalononitrile. The method involves vinylogous Michael addition of alkylidenemalononitrile to 2‐(1,3‐dioxo‐1H‐inden‐2(3H)‐ylidene)malononitrile, which formed by condensation of malononitrile and ninhydrin in the presence of Et3N, and the alcoholic solvent has participated in the reaction as a reagent. The method has the advantages of good yields and of not requiring a metal catalyst. The structures were confirmed spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses, and, in the case of 2c , by X‐ray crystallography. A plausible mechanism for this reaction is proposed (Scheme). 相似文献
7.
Maciej Makowski Anna Brzuszkiewicz Marek Lisowski Tadeusz Lis 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(7):o424-o426
The α,β‐dehydrophenylalanine residues influence the conformation of the title pentapeptide Boc0–Gly1–ΔZPhe2–Gly3–ΔEPhe4–l ‐Phe5–p‐NA ethanol solvate, C42H43N7O9·C2H5OH. The first unsaturated phenylalanyl (ΔZPhe2) and the third glycyl (Gly3) residues form a type I β turn, while the second unsaturated phenylalanyl (ΔEPhe4) and the last phenylalanyl (l ‐Phe5) residues are part of a type II β turn. All the amino acids in the peptide are linked trans to one another. The crystal structure is stabilized by intra‐ and intermolecular hydrogen bonds. 相似文献
8.
Reactions of 2‐(1,3‐Dithiolan‐2‐ylidene)malononitrile with Amino‐ and Hydrazinophosphorus Compounds: A Facile Route to Functionalized Phosphorus Heterocycles 下载免费PDF全文
Tarik E. Ali 《Journal of heterocyclic chemistry》2014,51(1):38-43
A facile and efficient route to functionalized phosphorus heterocycles was achieved by treatment of 2‐(1,3‐dithiolan‐2‐ylidene)malononitrile with amino‐ and hydrazinophosphorus compounds in the presence of a strong base via fragmentation of 1,3‐dithiolane ring. 相似文献
9.
Shar S. Al‐Shihry Anthony Linden 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):m40-m42
The title compound, [Fe(C5H5)(C21H21O3)], was obtained from successive Stobbe condensations between ketones and dimethyl succinate. The succinic anhydride five‐membered ring is distorted significantly from planarity, with the butadiene moiety being twisted by 49.3 (2)° from planarity and the C atoms at the succinic anhydride end of the alkene bonds showing significant pyramidalization. The cyclopentadiene rings of the ferrocenyl moiety adopt an almost eclipsed conformation. 相似文献
10.
Two‐step Synthesis of New γ‐Lactones via Cyclization of 7‐Chloro‐2‐(methoxycarbonyl)‐4‐6‐dimethylocta‐(2E,4E,6E)‐trienoic acid 下载免费PDF全文
Jean‐Marc Dillenschneider Laurent Dufossé Mireille Fouillaud Nuthathai Sutthiwong Roger Labia Alain Valla 《Journal of heterocyclic chemistry》2016,53(5):1439-1442
A new rapid synthesis of γ‐lactones, cis fused with a cyclopentenic ring by thermal cyclization of 7‐chloro‐2‐(methoxycarbonyl)‐4‐6‐dimethylocta‐7‐phenyl (or methyl) (2E,4E,6E)‐trienoic acids was reported. The key step implicates an intramolecular cyclization to a cyclopentenyl cation, according to an electrocyclic π2s + π2a conrotatory process, published in a recent paper (from the corresponding diacids). We have investigated the thermal behavior of the corresponding half‐esters since; if the cyclization obeys to the proposed mechanism, the diacids, half‐esters must also cyclize in a similar manner. Saponification of these led to γ‐dilactones via intermediary cyclopropanes. Mechanistic pathways were investigated. 相似文献
11.
Lakshminarasimhan Damodharan Vasantha Pattabhi Manoranjan Behera Sambasivarao Kotha 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(4):o216-o218
The title compounds, C19H19I2NO3 and C19H19Br2NO3, are derivatives of α‐aminoisobutyric acid with halogen substituents at the para and meta positions, respectively. The ethoxycarbonyl and formamide side chains attached to the Cα atom of the molecule adopt extended and folded conformations, respectively. The crystal structures are stabilized by N—H⃛O, C—H⃛O, C—Br⃛O and C—I⃛O interactions. 相似文献
12.
Paul C. Kline Bruce C. Noll Hongqiu Zhao Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(2):o137-o140
1‐(β‐d ‐Erythrofuranosyl)cytidine, C8H11N3O4, (I), a derivative of β‐cytidine, (II), lacks an exocyclic hydroxymethyl (–CH2OH) substituent at C4′ and crystallizes in a global conformation different from that observed for (II). In (I), the β‐d ‐erythrofuranosyl ring assumes an E3 conformation (C3′‐exo; S, i.e. south), and the N‐glycoside bond conformation is syn. In contrast, (II) contains a β‐d ‐ribofuranosyl ring in a 3T2 conformation (N, i.e. north) and an anti‐N‐glycoside linkage. These crystallographic properties mimic those found in aqueous solution by NMR with respect to furanose conformation. Removal of the –CH2OH group thus affects the global conformation of the aldofuranosyl ring. These results provide further support for S/syn–anti and N/anti correlations in pyrimidine nucleosides. The crystal structure of (I) was determined at 200 K. 相似文献
13.
Rui M. A. Pinto Jorge A. R. Salvador Jos A. Paixo 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(5):o279-o282
In the title compounds, C21H30O4, (I), and C23H34O4, (II), respectively, which are valuable intermediates in the synthesis of important steroid derivatives, rings A and B are cis‐(5β,10β)‐fused. The two molecules have similar conformations of rings A, B and C. The presence of the 5β,6β‐epoxide group induces a significant twist of the steroid nucleus and a strong flattening of the B ring. The different C17 substituents result in different conformations for ring D. Cohesion of the molecular packing is achieved in both compounds only by weak intermolecular interactions. The geometries of the molecules in the crystalline environment are compared with those of the free molecules as given by ab initio Roothan Hartree–Fock calculations. We show in this work that quantum mechanical ab initio methods reproduce well the details of the conformation of these molecules, including a large twist of the steroid nucleus. The calculated twist values are comparable, but are larger than the observed values, indicating a possible small effect of the crystal packing on the twist angles. 相似文献
14.
The total synthesis of the noncyanogenic cyanoglucoside 1 , originally isolated from Ilex warburgii, was achieved in nine steps (9% overall yield), starting from an optically pure Diels–Alder adduct ((+)‐ 3 ). The key step of the synthesis, the glycosidation, was carried out under Koenigs–Knorr conditions closely related to those developed for the total syntheses of (?)‐lithospermoside and (?)‐bauhinin. We had to tune the protecting groups used for the two free cis‐configured OH groups of the aglycone, which afforded the desired β‐d‐ glucoside intermediate 15 in very good yield (62%). 相似文献
15.
Jose G. Trujillo‐Ferrara Itzia I. Padilla‐Martínez Herbert Hpfl Francisco J. Martínez‐Martínez Norberto Farfan‐García Efrn V. García‐Bez 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o723-o726
The carboxylic acid group and the double bond are coplanar in (E)‐3‐(benzoxazol‐2‐yl)prop‐2‐enoic acid, C10H7NO3, whereas in isomeric (Z)‐3‐(benzoxazol‐2‐yl)prop‐2‐enoic acid, also C10H7NO3, they are almost orthogonal. In both isomers, a strong O—H⋯N hydrogen bond, with the carboxylic acid group as a donor and the pyridine‐like N atom as an acceptor, and weak C—H⋯O interactions contribute to the observed supramolecular structures, which are completed by π–π stacking interactions between oxazole and benzenoid rings. 相似文献
16.
Muhammad Altaf Helen Stoeckli‐Evans 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(9):o441-o445
The title compounds, C10H9N5O·H2O (L1·H2O) and C16H12N6O (L2), were synthesized by solvent‐free aldol condensation at room temperature. L1, prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 1:1 molar ratio, crystallized as a monohydrate. L2 was prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 2:1 molar ratio. By varying the conditions of crystallization it was possible to obtain two polymorphs, viz. L2‐I and L2‐II; both crystallized in the monoclinic space group P21/c. They differ in the orientation of one pyridine ring with respect to the plane of the imidazole ring. In L2‐I, this ring is oriented towards and above the imidazole ring, while in L2‐II it is rotated away from and below the imidazole ring. In all three molecules, there is a short intramolecular N—H...N contact inherent to the planarity of the systems. In L1·H2O, this involves an amino H atom and the C=N N atom, while in L2 it involves an amino H atom and an imidazole N atom. In the crystal structure of L1·H2O, there are N—H...O and O—H...O intermolecular hydrogen bonds which link the molecules to form two‐dimensional networks which stack along [001]. These networks are further linked via intermolecular N—H...N(cyano) hydrogen bonds to form an extended three‐dimensional network. In the crystal structure of L2‐I, symmetry‐related molecules are linked via N—H...N hydrogen bonds, leading to the formation of dimers centred about inversion centres. These dimers are further linked via N—H...O hydrogen bonds involving the amide group, also centred about inversion centres, to form a one‐dimensional arrangement propagating in [100]. In the crystal structure of L2‐II, the presence of intermolecular N—H...O hydrogen bonds involving the amide group results in the formation of dimers centred about inversion centres. These are linked via N—H...N hydrogen bonds involving the second amide H atom and the cyano N atom, to form two‐dimensional networks in the bc plane. In L2‐I and L2‐II, C—H...π and π–π interactions are also present. 相似文献
17.
18.
Paul C. Kline Hongqiu Zhao Bruce C. Noll Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(4):o215-o218
The title compound, also known as β‐erythroadenosine, C9H11N5O3, (I), a derivative of β‐adenosine, (II), that lacks the C5′ exocyclic hydroxymethyl (–CH2OH) substituent, crystallizes from hot ethanol with two independent molecules having different conformations, denoted (IA) and (IB). In (IA), the furanose conformation is OT1–E1 (C1′‐exo, east), with pseudorotational parameters P and τm of 114.4 and 42°, respectively. In contrast, the P and τm values are 170.1 and 46°, respectively, in (IB), consistent with a 2E–2T3 (C2′‐endo, south) conformation. The N‐glycoside conformation is syn (+sc) in (IA) and anti (−ac) in (IB). The crystal structure, determined to a resolution of 2.0 Å, of a cocrystal of (I) bound to the enzyme 5′‐fluorodeoxyadenosine synthase from Streptomyces cattleya shows the furanose ring in a near‐ideal OE (east) conformation (P = 90° and τm = 42°) and the base in an anti (−ac) conformation. 相似文献
19.
Joo Hyun Kim Nam‐Ho You Hoosung Lee 《Journal of polymer science. Part A, Polymer chemistry》2006,44(12):3729-3737
A series of statistical copolymers (poly[(9,9‐di‐n‐hexylfluorene)‐co‐2‐{2,6‐bis‐[2‐(4‐diphenylaminophenyl)vinyl]pyran‐4‐ylidene}malononitrile) were synthesized by the Suzuki coupling reaction. The copolymers showed absorption bands at 379 and 483–489 nm, which were attributed to the oligofluorene segments and the segments containing 2‐[2,6‐bis(2‐{4‐[(4‐bromophenyl)phenylamino]phenyl}vinyl)pyran‐4‐ylidene]malononitrile ( 3 ), respectively. The absorption band around 483–489 nm increased with the feed ratio of 3 . The photoluminescence (PL) spectra of the copolymers showed emission bands at 420 and 573–620 nm. As the feed ratio of 3 increased, the PL emission in the longer wavelength region redshifted, and the intensity increased as well. The electroluminescence (EL) spectrum of the copolymers showed a very weak emission at 420 nm. The PL and EL emission colors redshifted dramatically with the increase in the feed ratio of 3 . The highest occupied molecular orbital and lowest unoccupied molecular orbital levels of the model compound (2‐{2,6‐bis[2‐(4‐diphenylaminophenyl)vinyl]pyran‐4‐ylidene}malononitrile) were determined to be ?5.34 and ?3.14 eV, respectively. It was concluded that energy transfer took place from the oligofluorene blocks to the segments containing 3 and that direct charge trapping occurred in the segments containing 3 during the EL operation. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of the copolymer (x = 0.63, y = 0.37) containing 10 mol % 3 were very close to those (x = 0.67, y = 0.33) for National Television System Committee (NTSC) red with a maximum photometric power efficiency of 0.27 cd/A. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3729–3737, 2006 相似文献
20.
Vijayakumar N. Sonar M. Venkatraj Sean Parkin Peter A. Crooks 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(8):o493-o495
The asymmetric unit of the racemic form of the title compound, C12H15NOS, contains four crystallographically independent molecules. The olefinic bond connecting the 2‐thienyl and 1‐azabicyclo[2.2.2]octan‐3‐ol moieties has Z geometry. Strong hydrogen bonding occurs in a directed co‐operative O—H...O—H...O—H...O—H R44(8) pattern that influences the conformation of the molecules. Co‐operative C—H...π interactions between thienyl rings are also present. The average dihedral angle between adjacent thienyl rings is 87.09 (4)°. 相似文献