共查询到20条相似文献,搜索用时 691 毫秒
1.
Marco Brito‐Arias Enrique Durn‐Pramo Ignasi Mata Elies Molins 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(9):o537-o539
The syntheses and X‐ray analyses of two fucopyranosides, the monosaccharide benzyl 3,4‐di‐O‐acetyl‐2‐hydroxy‐β‐d ‐fucopyranoside, C17H22O7, and the disaccharide 1‐benzyl O‐(2,3‐di‐O‐acetyl‐4,6‐O‐benzylidene‐β‐d ‐glucopyranosyl)‐(12)‐3,4‐O‐isopropylidene‐β‐d ‐fucopyranoside, C33H40O12, are described. The different substituents induce small conformational changes on the fucopyranoside ring. However, the conformation of the benzyl group varies from (+)gauche for the monosaccharide to synperiplanar for the disaccharide. 相似文献
2.
Rubn A. Toscano Emma Maldonado Alfredo Ortega Jorge Crdenas 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):846-847
The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monohydrate, C26H36O9·H2O, has been determined by association with the known configuration of the glucose moiety. Its structure was established as 2β‐(O‐β‐d ‐glucopyranosyl)neocleroda‐3,13(16),14‐trien‐15,16‐epoxy‐18,19‐olide. Extensive hydrogen bonding among the hydroxyl groups of the sugar moiety forms layers which are interconnected by water molecules. 相似文献
3.
Shusheng Zhang Zhongwei Wang Ming Li Kui Jiao Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong‐Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):566-568
In both the title structures, O‐ethyl N‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d ‐glucopyranosyl)thiocarbamate, C17H25NO10S, and O‐methyl N‐(2,3,4,6‐tetra‐O‐acetyl‐β‐d ‐glucopyranosyl)thiocarbamate, C16H23NO10S, the hexopyranosyl ring adopts the 4C1 conformation. All the ring substituents are in equatorial positions. The acetoxymethyl group is in a gauche–gauche conformation. The S atom is in a synperiplanar conformation, while the C—N—C—O linkage is antiperiplanar. N—H?O intermolecular hydrogen bonds link the molecules into infinite chains and these are connected by C—H?O interactions. 相似文献
4.
Jarno Kansikas Kaija Sipil 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1383-1385
In the synthesis of 1‐phenyl‐2‐phenylthio‐2‐(tetrahydropyran‐2‐ylthio)ethanol, C19H22O2S2, four diastereoisomers are formed. Two non‐centrosymmetric enantiomeric forms which crystallize in space groups P212121 and Pna21 are presented. The former has an intramolecular hydrogen bond between the hydroxyl group and the O atom of the tetrahydropyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O atom of the tetrahydropyranyl group of a neighbouring molecule, joining the molecules into chains in the c‐axis direction; the O?O distances are 2.962 (4) and 2.764 (3) Å, respectively. The tetrahydropyran rings are in chair conformations in both isomers and the S side chain has an equatorial orientation in the former, but an axial orientation in the latter molecule. 相似文献
5.
Ivanka Matijai Gordana Pavlovi Rudolf Trojko Jr 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(4):o184-o186
The X‐ray crystal structure analysis of the title compound, C17H30O8, revealed a 4C1 conformation of the pyranosyl ring [Cremer–Pople puckering parameters of Q = 0.568 (2) Å, θ = 5.1 (2) and ϕ = 218 (3)°]. The structure shows no deviations from the geometric parameters of pyranoside carbohydrates. The hydroxyl groups participate in O—H⃛O hydrogen bonds, forming a two‐dimensional pattern [O⃛O = 2.811 (3) and 2.995 (3) Å]. 相似文献
6.
Lars Eriksson Roland Stenutz Gran Widmalm 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):702-704
The crystal structure of methyl 4‐O‐β‐l ‐fucopyranosyl α‐d ‐glucopyranoside hemihydrate C13H24O10·0.5H2O is organized in sheets with antiparallel strands, where hydrophobic interaction accounts for partial stabilization. Infinite hydrogen‐bonding networks are observed within each layer as well as between layers; some of these hydrogen bonds are mediated by water molecules. The conformation of the disaccharide is described by the glycosidic torsion angles: ?H = ?6.1° and ψH = 34.3°. The global energy minimum conformation as calculated by molecular mechanics in vacuo has ?H = ?58° and ψH = ?20°. Thus, quite substantial changes are observed between the in vacuo structure and the crystal structure with its infinite hydrogen‐bonding networks. 相似文献
7.
Anthony Linden A. S. Muhammad Sofian C. Kuan Lee 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o711-o714
At 160 K, the glucopyranosyl ring in 1,6‐dichloro‐1,6‐dideoxy‐β‐d ‐fructofuranosyl 4‐chloro‐4‐deoxy‐α‐d ‐glucopyranoside monohydrate, C12H19Cl3O8·H2O, has a near ideal 4C1 chair conformation, while the fructofuranosyl ring has a 4T3 conformation. The conformation of the sugar molecule is quite different to that of sucralose, particularly in the conformation about the glycosidic linkage, which affects the observed pattern of intramolecular hydrogen bonds. A complex series of intermolecular hydrogen bonds links the sugar and water molecules into an infinite three‐dimensional framework. 相似文献
8.
Jaromír Marek Dagmar Vesel Margita Likov Milan
emli
ka 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(3):o127-o128
The crystal structure of pomiferin, 3‐(3,4‐dihydroxyphenyl)‐5‐hydroxy‐8,8‐dimethyl‐6‐(3‐methylbut‐2‐enyl)‐4H,8H‐pyrano[2,3‐h]chromen‐4‐one, C25H24O6, has been determined. The benzopyranone ring system is nearly planar and the dihedral angle between the phenyl ring and the benzopyranone moiety is 40.85 (4)°. The crystal structure is stabilized by a one‐dimensional chain of inter‐ and intramolecular O—H⃛O hydrogen bonds, with O⃛O distances in the range 2.5546 (15)–2.7999 (16) Å. 相似文献
9.
Valery Belakhov Mark Botoshansky Timor Baasov 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):m450-m452
The hexopyranosyl ring of the title compound, [Hg(CH3)(C9H15O7S)], adopts the 4C1 chair conformation, and the anomeric configuration of the thiomethylmercury linkage is β. The compound exists as two symmetry‐independent conformers, A and B, within the unit cell, and each shows an almost linear S—Hg—C arrangement. Most of the bond distances and angles in A and B are similar, although a marked difference exists in the side‐chain conformation. Weak secondary intramolecular (between Hg and ring O) and intermolecular (between A and B conformers) interactions are documented. 相似文献
10.
Anthony Linden A. S. Muhammad Sofian C. Kuan Lee 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):o718-o720
At 160 K, one of the Cl atoms in the furanoid moiety of 3‐O‐acetyl‐1,6‐dichloro‐1,4,6‐trideoxy‐β‐d ‐fructofuranosyl 2,3,6‐tri‐O‐acetyl‐4‐chloro‐4‐deoxy‐α‐d ‐galactopyranoside, C20H27Cl3O11, is disordered over two orientations, which differ by a rotation of about 107° about the parent C—C bond. The conformation of the core of the molecule is very similar to that of 3‐O‐acetyl‐1,4,6‐trichloro‐1,4,6‐trideoxy‐β‐d ‐tagatofuranosyl 2,3,6‐tri‐O‐acetyl‐4‐chloro‐4‐deoxy‐α‐d ‐galactopyranoside, particularly with regard to the conformation about the glycosidic linkage. 相似文献
11.
Anthony Linden C. Kuan Lee A. S. Muhammad Sofian 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1098-1100
At 160 K, the glucopyranosyl ring of the title compound, C20H28ClIO13, has a near‐ideal 4C1 conformation and the fructofuranosyl ring has a twist 4T3 conformation. The two hydroxy groups are involved in intra‐ and intermolecular hydrogen bonds, with the latter interactions linking the molecules into infinite one‐dimensional chains. The absolute configuration of the molecule has been determined. 相似文献
12.
Shiming Li Knut Lundquist Vratislav Langer 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(10):o625-o627
Compounds (2R*,3S*)‐1‐(3,4‐dimethoxyphenyl)‐3‐{3‐methoxy‐2‐[(2R*)‐tetrahydropyran‐2‐yloxy]phenyl}‐2,3‐epoxy‐1‐propanone, C23H26O7, (I), and trans‐1‐(3,4‐dimethoxyphenyl)‐3‐[3‐methoxy‐2‐(methoxymethoxy)phenyl]‐2,3‐epoxy‐1‐propanone, C20H22O7, (II), were obtained on epoxidation of chalcones. The stereochemistries of (I) and (II) were elucidated. In both compounds, the substituents on the oxirane ring are trans‐oriented. Compound (I) was obtained together with a diastereometric form that differs from (I) with respect to the configuration of the asymmetric C atom in the tetrahydropyran group. The geometries of the substituted oxirane rings of (I) and (II) are very similar. The hydrogen‐bonding patterns, mediated via weak C—H⋯O interactions, differ considerably. The crystal structures of (I) and (II) are compared with those of related chalcone epoxides. The conversion of (I) and (II) into lignin‐related phenylcoumarans is discussed. 相似文献
13.
Magdalena Maecka Werner Massa Elbieta Budzisz 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o762-o764
The title compound, C18H14O4, forms a supramolecular structure viaπ–π stacking and weak C—H⋯O and C—H⋯π interactions. The benzopyran moiety is almost planar. The benzene ring of the phenylmethyl acetate substituent is nearly perpendicular to the fused benzene and pyran rings and also to the methyl acetate group. 相似文献
14.
Zun‐Ting Zhang Qian‐Guang Liu Xiao‐Bing Wang Jian‐Bin Zheng Kai‐Bai Yu 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(1):o29-o31
The title compound, 5‐hydroxy‐4′,7‐dimethoxyisoflavone, C17H14O5, is composed of a benzopyranone moiety, a phenyl moiety and two methoxy groups. The benzopyranone ring is not coplanar with the phenyl ring, the dihedral angle between them being 56.28 (3)°. The two methoxy groups are nearly coplanar with their corresponding rings, having C—C—O—C torsion angles of 2.9 (2) and 5.9 (2)°. The molecules are linked by C—H·O hydrogen bonds into sheets containing classical centrosymmetric (8) rings. The sheets are further linked by aromatic π–π stacking interactions and C—H·O hydrogen bonds into a supramolecular structure. 相似文献
15.
Amitabh Jha Sanjay Malhotra Virinder S. Parmar William Errington 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):899-900
The title compound, 2,2‐dimethylchroman‐6‐ol, C11H14O2, has been identified as a side product from the condensation of hydroquinone with 2‐methylbut‐3‐en‐2‐ol. The pyran ring has a half‐chair conformation. The hydroxyl groups are involved in intermolecular hydrogen bonding which generates infinite spiral chains around the fourfold screw axes; the O?O hydrogen‐bonded distances are 2.661 (1) Å. 相似文献
16.
C. Foces-Foces 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(3):298-301
Two of the title compounds, 1,6-anhydro-2,3-O-(S)-benzylidene-β-d -mannopyranose, C13H14O5, (I), and 1,6-anhydro-4-O-benzyl-β-d -mannopyranose, C13H16O5, (II), are derived from β-d -mannopyranose, while the third, 1,6-anhydro-3,4-O-(S)-benzylidene-β-d -galactopyranose, C13H14O5, (III), is derived from β-d -galactopyranose. In the crystal packing, each hydroxyl group is involved in O—H⃛O hydrogen bonds, where the acceptor group is the other hydroxyl group in (II), or the endocyclic O atoms of the dioxolane [in (I)], anhydro [in (II)] or pyranose [in (III)] rings. Differences in the crystal packing arise from the contrasting O—H⃛O hydrogen-bonding environments. 相似文献
17.
Jan W. Bats Uwe Parsch Joachim W. Engels 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1129-1131
Crystals of 4,2′‐anhydro‐5‐(β‐d ‐arabinofuranosyl)uracil, (I), obtained from an aqueous solution, were characterized as the dihydrate, C9H10N2O5·2H2O, (Ia). In air, these crystals slowly transform to the monohydrate, C9H10N2O5·H2O, (Ib), but remain crystalline. The solid‐state transformation proceeds with the loss of one water molecule and a rearrangement of hydrogen‐bonded layers of molecules. The furanose ring in (I) has an approximate C4′‐exo,O4′‐endo twist conformation. The central five‐membered ring is slightly puckered. The uracil group is planar within experimental uncertainty. 相似文献
18.
Leonardo Lo Presti Raffaella Soave Riccardo Destro 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(4):o199-o201
The title compound, (7R,8S)‐7,8‐dihydroxy‐3,7‐dimethyl‐6‐oxo‐7,8‐dihydro‐6H‐isochromene‐5‐carbaldehyde, C12H12O5, is a trans‐vicinal diol. Of the two fused rings, which lie approximately in the same plane, the pyran ring is almost perfectly planar, while the cyclohexenone ring adopts a slightly distorted half‐chair conformation. The crystal packing is dictated by two strong intermolecular O—H⃛O interactions, one involving hydroxy and keto groups, the other involving two hydroxy groups. Molecules are linked together through twofold axes, forming zigzag ribbons extended along the a axis. 相似文献
19.
Joe D. Sauer Hassan Y. Elnagar Frank R. Fronczek 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(2):o62-o64
Crystalline N,N‐dimethyl‐n‐tetradecylamine oxide has been prepared by reaction of liquid N,N‐dimethyl‐n‐tetradecylamine with 70% H2O2 in the presence of CO2 as catalyst. The resulting soft low‐melting solid was crystallized as the dihydrate, viz. C16H35NO·2H2O. The extended hydrocarbon chains pack in a parallel fashion, with the N‐oxide ends of the molecules forming hydrogen bonds with the water molecules in hydrophilic layers. The N—O distance is 1.411 (3) Å. 相似文献
20.
A. Subbiah Pandi D. Velmurugan S. Shanmuga Sundara Raj Hoong‐Kun Fun P. R. Seshadri D. Thirumalai 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):821-824
10‐(4‐Fluorophenyl)‐3,3,6,6,9‐pentamethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione, C24H28FNO2, (I), crystallizes with two crystallographically independent molecules (which differ slightly in conformation), while 10‐(4‐fluorophenyl)‐9‐propyl‐3,3,6,6‐tetramethyl‐3,4,6,7,9,10‐hexahydroacridine‐1,8(2H,5H)‐dione, C26H32FNO2, (II), crystallizes with one molecule per asymmetric unit. In both structures, the central ring in the acridine moiety is in a sofa conformation, while the outer rings adopt intermediate half‐chair/sofa conformations. The central pyridine ring is orthogonal to the substituted phenyl ring. In both structures, the packing of the crystal is stabilized by C—H?O intermolecular hydrogen bonds. 相似文献