共查询到20条相似文献,搜索用时 828 毫秒
1.
Frank Seela Padmaja Chittepu Yang He Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(3):o173-o176
In 2‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐1,2,4‐triazine‐3,5(2H,4H)‐dione (6‐aza‐2′‐deoxyuridine), C8H11N3O5, (I), the conformation of the glycosylic bond is between anti and high‐anti [χ = −94.0 (3)°], whereas the derivative 2‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐N4‐(2‐methoxybenzoyl)‐1,2,4‐triazine‐3,5(2H,4H)‐dione (N3‐anisoyl‐6‐aza‐2′‐deoxyuridine), C16H17N3O7, (II), displays a high‐anti conformation [χ = −86.4 (3)°]. The furanosyl moiety in (I) adopts the S‐type sugar pucker (2T3), with P = 188.1 (2)° and τm = 40.3 (2)°, while the sugar pucker in (II) is N (3T4), with P = 36.1 (3)° and τm = 33.5 (2)°. The crystal structures of (I) and (II) are stabilized by intermolecular N—H⋯O and O—H⋯O interactions. 相似文献
2.
Wenhui Zhang Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(11):o557-o560
3‐Deoxy‐3‐fluoro‐d ‐glucopyranose crystallizes from acetone to give a unit cell containing two crystallographically independent molecules. One of these molecules (at site A) is structurally homogeneous and corresponds to 3‐deoxy‐3‐fluoro‐β‐d ‐glucopyranose, C6H11FO5, (I). The second molecule (at site B) is structurally heterogeneous and corresponds to a mixture of (I) and 3‐deoxy‐3‐fluoro‐α‐d ‐glucopyranose, (II); treatment of the diffraction data using partial‐occupancy oxygen at the anomeric center gave a high‐quality packing model with an occupancy ratio of 0.84:0.16 for (II):(I) at site B. The mixture of α‐ and β‐anomers at site B appears to be accommodated in the lattice because hydrogen‐bonding partners are present to hydrogen bond to the anomeric OH group in either an axial or equatorial orientation. Cremer–Pople analysis of (I) and (II) shows the pyranosyl ring of (II) to be slightly more distorted than that of (I) [θ(I) = 3.85 (15)° and θ(II) = 6.35 (16)°], but the general direction of distortion is similar in both structures [ϕ(I) = 67 (2)° (BC1,C4) and ϕ(II) = 26.0 (15)° (C3TBC1); B = boat conformation and TB = twist‐boat conformation]. The exocyclic hydroxymethyl (–CH2OH) conformation is gg (gauche–gauche) (H5 anti to O6) in both (I) and (II). Structural comparisons of (I) and (II) to related unsubstituted, deoxy and fluorine‐substituted monosaccharides show that the gluco ring can assume a wide range of distorted chair structures in the crystalline state depending on ring substitution patterns. 相似文献
3.
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
4.
Xiaosong Hu Qingfeng Pan Bruce C. Noll Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):o67-o70
Methyl β‐d ‐galactopyranosyl‐(1→4)‐α‐d ‐mannopyranoside methanol 0.375‐solvate, C13H24O11·0.375CH3OH, (I), was crystallized from a methanol–ethanol solvent system in a glycosidic linkage conformation, with ϕ′ (O5Gal—C1Gal—O1Gal—C4Man) = −68.2 (3)° and ψ′ (C1Gal—O1Gal—C4Man—C5Man) = −123.9 (2)°, where the ring is defined by atoms O5/C1–C5 (monosaccharide numbering); C1 denotes the anomeric C atom and C6 the exocyclic hydroxymethyl C atom in the βGalp and αManp residues, respectively. The linkage conformation in (I) differs from that in crystalline methyl α‐lactoside [methyl β‐d ‐galactopyranosyl‐(1→4)‐α‐d ‐glucopyranoside], (II) [Pan, Noll & Serianni (2005). Acta Cryst. C 61 , o674–o677], where ϕ′ is −93.6° and ψ′ is −144.8°. An intermolecular hydrogen bond exists between O3Man and O5Gal in (I), similar to that between O3Glc and O5Gal in (II). The structures of (I) and (II) are also compared with those of their constituent residues, viz. methyl α‐d ‐mannopyranoside, methyl α‐d ‐glucopyranoside and methyl β‐d ‐galactopyranoside, revealing significant differences in the Cremer–Pople puckering parameters, exocyclic hydroxymethyl group conformations and intermolecular hydrogen‐bonding patterns. 相似文献
5.
Qingfeng Pan Bruce C. Noll Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(2):o82-o85
Methyl β‐l ‐lactoside, C13H24O11, (II), is described by glycosidic torsion angles ϕ (O5Gal—C1Gal—O4Glc—C4Glc) and ψ (C1Gal—O1Gal—C4Glc—C5Glc) of 93.89 (13) and −127.43 (13)°, respectively, where the ring atom numbering conforms to the convention in which C1 is the anomeric C atom and C6 is the exocyclic hydroxymethyl (CH2OH) C atom in both residues (Gal is galactose and Glc is glucose). Substitution of l ‐Gal for d ‐Gal in the biologically relevant disaccharide, methyl β‐lactoside [Stenutz, Shang & Serianni (1999). Acta Cryst. C 55 , 1719–1721], (I), significantly alters the glycosidic linkage interface. In the crystal structure of (I), one inter‐residue (intramolecular) hydrogen bond is observed between atoms H3OGlc and O5Gal. In contrast, in the crystal structure of (II), inter‐residue hydrogen bonds are observed between atoms H6OGlc and O5Gal, H6OGlc and O6Gal, and H3OGlc and O2Gal, with H6OGlc serving as a donor with two intramolecular acceptors. 相似文献
6.
Wenhui Zhang Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(9):o484-o487
The title compound, C13H24O11·4H2O, (I), crystallized from water, has an internal glycosidic linkage conformation having ϕ′ (O5Gal—C1Gal—O1Gal—C4All) = −96.40 (12)° and ψ′ (C1Gal—O1Gal—C4All—C5All) = −160.93 (10)°, where ring‐atom numbering conforms to the convention in which C1 denotes the anomeric C atom, C5 the ring atom bearing the exocyclic hydroxymethyl group, and C6 the exocyclic hydroxymethyl (CH2OH) C atom in the βGalp and βAllp residues. Internal linkage conformations in the crystal structures of the structurally related disaccharides methyl β‐lactoside [methyl β‐d ‐galactopyranosyl‐(1→4)‐β‐d ‐glucopyranoside] methanol solvate [Stenutz, Shang & Serianni (1999). Acta Cryst. C 55 , 1719–1721], (II), and methyl β‐cellobioside [methyl β‐d ‐glucopyranosyl‐(1→4)‐β‐d ‐glucopyranoside] methanol solvate [Ham & Williams (1970). Acta Cryst. B 26 , 1373–1383], (III), are characterized by ϕ′ = −88.4 (2)° and ψ′ = −161.3 (2)°, and ϕ′ = −91.1° and ψ′ = −160.7°, respectively. Inter‐residue hydrogen bonding is observed between O3Glc and O5Gal/Glc in the crystal structures of (II) and (III), suggesting a role in determining their preferred linkage conformations. An analogous inter‐residue hydrogen bond does not exist in (I) due to the axial orientation of O3All, yet its internal linkage conformation is very similar to those of (II) and (III). 相似文献
7.
Frank Seela Xiaohua Peng Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o94-o97
The structures of the isomeric nucleosides 4‐nitro‐1‐(β‐d ‐ribofuranosyl)‐1H‐indazole, C12H13N3O6, (I), and 4‐nitro‐2‐(β‐d ‐ribofuranosyl)‐2H‐indazole, C12H13N3O6, (II), have been determined. For compound (I), the conformation of the glycosylic bond is anti [χ = −93.6 (6)°] and the sugar puckering is C2′‐exo–C3′‐endo. Compound (II) shows two conformations in the crystalline state which differ mainly in the sugar pucker; type 1 adopts the C2′‐endo–C3′‐exo sugar puckering associated with a syn base orientation [χ = 43.7 (6)°] and type 2 shows C2′‐exo–C3′‐endo sugar puckering accompanied by a somewhat different syn base orientation [χ = 13.8 (6)°]. 相似文献
8.
Wenhui Zhang Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(1):o7-o11
Methyl β‐d ‐galactopyranosyl‐(1→4)‐β‐d ‐xylopyranoside, C12H22O10, (II), crystallizes as colorless needles from water with positional disorder in the xylopyranosyl (Xyl) ring and no water molecules in the unit cell. The internal glycosidic linkage conformation in (II) is characterized by a ϕ′ torsion angle (C2′Gal—C1′Gal—O1′Gal—C4Xyl) of 156.4 (5)° and a ψ′ torsion angle (C1′Gal—O1′Gal—C4Xyl—C3Xyl) of 94.0 (11)°, where the ring atom numbering conforms to the convention in which C1 denotes the anomeric C atom, and C5 and C6 denote the hydroxymethyl (–CH2OH) C atoms in the β‐Xyl and β‐Gal residues, respectively. By comparison, the internal linkage conformation in the crystal structure of the structurally related disaccharide, methyl β‐lactoside [methyl β‐d ‐galactopyranosyl‐(1→4)‐β‐d ‐glucopyranoside], (III) [Stenutz, Shang & Serianni (1999). Acta Cryst. C 55 , 1719–1721], is characterized by ϕ′ = 153.8 (2)° and ψ′ = 78.4 (2)°. A comparison of β‐(1→4)‐linked disaccharides shows considerable variability in both ϕ′ and ψ′, with the range in the latter (∼38°) greater than that in the former (∼28°). Inter‐residue hydrogen bonding is observed between atoms O3Xyl and O5′Gal in the crystal structure of (II), analogous to the inter‐residue hydrogen bond detected between atoms O3Glc and O5′Gal in (III). The exocyclic hydroxymethyl conformations in the Gal residues of (II) and (III) are identical (gauche–trans conformer). 相似文献
9.
Frank Seela Yang He Henning Eickmeier 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(4):o194-o196
In the title compound, 3‐amino‐2‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐6‐methyl‐1,2,4‐triazin‐5(2H)‐one, C9H14N4O4, the conformation of the N‐glycosidic bond is high‐anti and the 2‐deoxyribofuranosyl moiety adopts a North sugar pucker (2T3). The orientation of the exocyclic C—C bond between the –CH2OH group and the five‐membered ring is ap (gauche, trans). The crystal packing is such that the nucleobases lie parallel to the ac plane; the planes are connected via hydrogen bonds involving the five‐membered ring. 相似文献
10.
Frank Seela Yunlong Zhang Kuiying Xu Henning Eickmeier 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(1):o60-o62
In the title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐eythro‐pentofuranosyl)‐3‐vinyl‐1H‐pyrazolo[3,4‐d]pyrimidine monohydrate, C12H15N5O3·H2O, the conformation of the glycosyl bond is anti. The furanose moiety is in an S conformation with an unsymmetrical twist, and the conformation at the exocyclic C—C(OH) bond is +sc (gauche, gauche). The vinyl side chain is bent out of the heterocyclic ring plane by 147.5 (5)°. The three‐dimensional packing is stabilized by O—H·O, O—H·N and N—H·O hydrogen bonds. 相似文献
11.
Frank Seela Helmut Rosemeyer Alexander Melenewski Eva‐Maria Heithoff Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o142-o144
In the monohydrate of 2‐amino‐8‐(2‐deoxy‐α‐d ‐erythro‐pentofuranosyl)‐8H‐imidazo[1,2‐a][1,3,5]triazin‐4‐one, C10H13N5O4·H2O, denoted (I) or αZd, the conformation of the N‐glycosylic bond is in the high‐anti range [χ = 87.5 (3)°]. The 2′‐deoxyribofuranose moiety adopts a C2′‐endo,C3′‐exo(2′T3′) sugar puckering (S‐type sugar) and the conformation at the C4′—C5′ bond is ?sc (trans). 相似文献
12.
Xiaosong Hu Wenhui Zhang Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(4):o146-o150
Methyl 2‐acetamido‐2‐deoxy‐β‐d ‐glucopyranoside (β‐GlcNAcOCH3), (I), crystallizes from water as a dihydrate, C9H17NO6·H2O, containing two independent molecules [denoted (IA) and (IB)] in the asymmetric unit, whereas the crystal structure of methyl 2‐formamido‐2‐deoxy‐β‐d ‐glucopyranoside (β‐GlcNFmOCH3), (II), C8H15NO6, also obtained from water, is devoid of solvent water molecules. The two molecules of (I) assume distorted 4C1 chair conformations. Values of ϕ for (IA) and (IB) indicate ring distortions towards BC2,C5 and C3,O5B, respectively. By comparison, (II) shows considerably more ring distortion than molecules (IA) and (IB), despite the less bulky N‐acyl side chain. Distortion towards BC2,C5 was observed for (II), similar to the findings for (IA). The amide bond conformation in each of (IA), (IB) and (II) is trans, and the conformation about the C—N bond is anti (C—H is approximately anti to N—H), although the conformation about the latter bond within this group varies by ∼16°. The conformation of the exocyclic hydroxymethyl group was found to be gt in each of (IA), (IB) and (II). Comparison of the X‐ray structures of (I) and (II) with those of other GlcNAc mono‐ and disaccharides shows that GlcNAc aldohexopyranosyl rings can be distorted over a wide range of geometries in the solid state. 相似文献
13.
Frank Seela Anup M. Jawalekar Simone Budow Henning Eickmeier 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(9):o562-o564
In the title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐6‐methylsulfanyl‐1H‐pyrazolo[3,4‐d]pyrimidine, C11H16N5O3S, the conformation of the glycosidic bond is between anti and high anti. The 2′‐deoxyribofuranosyl moiety adopts the C3′‐exo–C4′‐endo conformation (3T4, S‐type sugar pucker), and the conformation at the exocyclic C—C bond is +sc (+gauche). The exocyclic 6‐amine group and the 2‐methylsulfanyl group lie on different sides of the heterocyclic ring system. The molecules form a three‐dimensional hydrogen‐bonded network that is stabilized by O—H⋯N, N—H⋯O and C—H⋯O hydrogen bonds. 相似文献
14.
Junlin He Frank Seela Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):o593-o595
In the title regioisomeric nucleosides, alternatively called 1‐(2‐deoxy‐β‐d ‐erythro‐furanosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine, C10H12N4O3, (II), and 2‐(2‐deoxy‐β‐d ‐erythro‐furanosyl)‐2H‐pyrazolo[3,4‐d]pyrimidine, C10H12N4O3, (III), the conformations of the glycosylic bonds are anti [?100.4 (2)° for (II) and 15.0 (2)° for (III)]. Both nucleosides adopt an S‐type sugar pucker, which is C2′‐endo‐C3′‐exo (2T3) for (II) and 3′‐exo (between 3E and 4T3) for (III). 相似文献
15.
Wenhui Zhang Bruce C. Noll Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o578-o581
The β‐pyranose form, (III), of 3‐deoxy‐d ‐ribo‐hexose (3‐deoxy‐d ‐glucose), C6H12O5, crystallizes from water at 298 K in a slightly distorted 4C1 chair conformation. Structural analyses of (III), β‐d ‐glucopyranose, (IV), and 2‐deoxy‐β‐d ‐arabino‐hexopyranose (2‐deoxy‐β‐d ‐glucopyranose), (V), show significantly different C—O bond torsions involving the anomeric carbon, with the H—C—O—H torsion angle approaching an eclipsed conformation in (III) (−10.9°) compared with 32.8 and 32.5° in (IV) and (V), respectively. Ring carbon deoxygenation significantly affects the endo‐ and exocyclic C—C and C—O bond lengths throughout the pyranose ring, with longer bonds generally observed in the monodeoxygenated species (III) and (V) compared with (IV). These structural changes are attributed to differences in exocyclic C—O bond conformations and/or hydrogen‐bonding patterns superimposed on the direct (intrinsic) effect of monodeoxygenation. The exocyclic hydroxymethyl conformation in (III) (gt) differs from that observed in (IV) and (V) (gg). 相似文献
16.
Thomas E. Klepach Meredith Reed Bruce C. Noll Allen G. Oliver Anthony S. Serianni 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(12):o601-o606
Methyl β‐allolactoside [methyl β‐d ‐galactopyranosyl‐(1→6)‐β‐d ‐glucopyranoside], (II), was crystallized from water as a monohydrate, C13H24O11·H2O. The βGalp and βGlcp residues in (II) assume distorted 4C1 chair conformations, with the former more distorted than the latter. Linkage conformation is characterized by ϕ′ (C2Gal—C1Gal—O1Gal—C6Glc), ψ′ (C1Gal—O1Gal—C6Glc—C5Glc) and ω (C4Glc—C5Glc—C6Glc—O1Gal) torsion angles of 172.9 (2), −117.9 (3) and −176.2 (2)°, respectively. The ψ′ and ω values differ significantly from those found in the crystal structure of β‐gentiobiose, (III) [Rohrer et al. (1980). Acta Cryst. B 36 , 650–654]. Structural comparisons of (II) with related disaccharides bound to a mutant β‐galactosidase reveal significant differences in hydroxymethyl conformation and in the degree of ring distortion of the βGlcp residue. Structural comparisons of (II) with a DFT‐optimized structure, (IIC), suggest a link between hydrogen bonding, pyranosyl ring deformation and linkage conformation. 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.
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
19.
Frank Seela Matthias Zulauf Hans Reuter Guido Kastner 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):489-491
The isomorphous structures of the title molecules, 4‐amino‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐3‐iodo‐1H‐pyrazolo‐[3,4‐d]pyrimidine, (I), C10H12IN5O3, and 4‐amino‐3‐bromo‐1‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐1H‐pyrazolo[3,4‐d]pyrimidine, (II), C10H12BrN5O3, have been determined. The sugar puckering of both compounds is C1′‐endo (1′E). The N‐glycosidic bond torsion angle χ1 is in the high‐anti range [?73.2 (4)° for (I) and ?74.1 (4)° for (II)] and the crystal structure is stabilized by hydrogen bonds. 相似文献
20.
Jaromír Marek Jn Van
o Oga vajlenov 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(12):m509-m511
The title polymeric compound, catena‐poly[dipotassium [bis[μ‐N‐salicylidene‐β‐alaninato(2−)]‐κ4O,N,O′:O′′;κ4O′′:O,N,O′‐dicopper(II)]‐di‐μ‐isothiocyanato‐κ2N:S;κ2S:N], {K[Cu(NCS)(C10H9NO3)]}n, consists of [isothiocyanato(N‐salicylidene‐β‐alaninato)copper(II)]− anions connected through the two three‐atom thiocyanate (μ‐NCS) and the two anti,anti‐μ‐carboxylate bridges into infinite one‐dimensional polymeric anions, with coulombically interacting K+ counter‐ions with coordination number 7 constrained between the chains. The CuII atoms adopt a distorted tetragonal–bipyramidal coordination, with three donor atoms of the tridentate Schiff base and one N atom of the bridging μ‐NCS ligand in the basal plane. The first axial position is occupied by a thiocyanate S atom of a symmetry‐related μ‐NCS ligand at an apical distance of 2.9770 (8) Å, and the second position is occupied by an O atom of a bridging carboxylate group from an adjacent coordination unit at a distance of 2.639 (2) Å. 相似文献