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1.  Phenyl 2-amino-N,6-O-dibenzyl-2,3-N,O-carbonyl-2-de­oxy-1-thio-β-d-glucopyran­oside 
In the crystal structure of the title compound, C27H27NO5S, the pyran­ose ring adopts a 4 C 1 chair conformation with puckering parameters Q = 0.639 (2) Å, θ = 174.11 (18) and ϕ = 256 (2)°. The presence of the 2,3-trans-oxazolidinone fixes the conformation of the pyran­ose ring. The phenyl group attached to the S atom and the benzyl group bonding to the N atom are each disordered over two positions with site occupancies of 0.624 (3):0.376 (3) and 0.526 (3):0.474 (3), respectively. An inter­molecular O—H⋯O hydrogen bond is observed.
PMCID: PMC2959351  PMID: 21201084
2.  4-De­oxy-4-fluoro-β-d-gluco­pyranose 
4-De­oxy-4-fluoro-β-d-glucopyran­ose, C6H11FO5, (I), crystallizes from water at room temperature in a slightly distorted 4 C 1 chair con­formation. The observed chair distortion differs from that observed in β-d-glucopyran­ose [Kouwijzer, van Eijck, Kooijman & Kroon (1995 ▶). Acta Cryst. B51, 209–220], (II), with the former skewed toward a B C3,O5 (boat) conformer and the latter toward an O5 TB C2 (twist–boat) conformer, based on Cremer–Pople analysis. The exocyclic hy­droxy­methyl group conformations in (I) and (II) are similar; in both cases, the O—C—C—O torsion angle is ∼−60° (gg con­former). Inter­molecular hydrogen bonding in the crystal structures of (I) and (II) is conserved in that identical patterns of donors and acceptors are observed for the exocyclic substituents and the ring O atom of each monosaccharide. Inspection of the crystal packing structures of (I) and (II) reveals an essentially identical packing configuration.
PMCID: PMC3089016  PMID: 20921614
3.  3,4-Dicyano­phenyl 2,3,4,6-tetra-O-acetyl-α-d-glucopyran­oside 
The title compound, C22H22N2O10, was prepared by the glycosidation method through nitrite displacement on substituted nitro­phthalonitrile. The mol­ecule contains a benzene ring, two nitrile groups and an acetyl-protected d-glucose fragment which adopts a chair conformation. The absolute configuration was determined by the use of d-glucose as starting material. All substituents of the protected sugar are in equatorial positions, with the exclusive presence of the α-anomer. The crystal packing is stabilized by C—H⋯O and C—H⋯N hydrogen-bonding inter­actions.
PMCID: PMC2915021  PMID: 21200940
4.  Methyl 3-O-α-l-fucopyranosyl β-d-glucopyran­oside tetra­hydrate 
The title compound, C13H24O10·4H2O, is the methyl glycoside of a disaccharide structural element present in the backbone of the capsular polysaccharide from Klebsiella K1, which contains only three sugars and a substituent in the polysaccharide repeating unit. The conformation of the title disaccharide is described by the glycosidic torsion angles ϕH = 51.1 (1)° and ψH = 25.8 (1)°. In the crystal, a number of O—H⋯O hydrogen bonds link the methyl glycoside and water mol­ecules, forming a three-dimensional network. One water mol­ecule is disordered over two positions with occupancies of 0.748 (4) and 0.252 (4).
PMCID: PMC3515273  PMID: 23284493
5.  Ethyl 3,6-di-O-benzyl-2-de­oxy-N-phthalimido-1-thio-β-d-glucopyran­oside 
In the title compound, C30H31NO6S, the plane of the N-phthalimido group is nearly orthogonal to the least-squares plane of the sugar ring (defined by atoms C2, C3, C5 and O5 using standard glucose nomenclature), making a dihedral angle of 72.8 (1)°. The thio­ethyl group has the exo-anomeric conformation. The hy­droxy group forms an inter­molecular hydrogen bond to the O atom in the sugar ring, generating [100] chains. There are four close π–π contacts with centroid–centroid distances less than 4.0 Å, all with dihedral angles between the inter­acting π systems of only ≃ 8°, supporting energetically favourable stacking inter­actions.
PMCID: PMC3011472  PMID: 21589536
6.  Ethyl 4,6-O-benzyl­idene-2-de­oxy-N-phthalimido-1-thio-β-d-glucopyran­oside 
In the title compound, C23H23NO6S, the plane of the N-phthalimido group makes a dihedral angle of 67.4 (1)° with the least square plane of the sugar ring defined by the C2, C3, C5 and O5 atoms using standard glucose nomenclature. The thio­ethyl group has the exo-anomeric conformation. In the crystal, inter­molecular hydrogen bonds involving the hy­droxy groups and the carbonyl O atoms of adjacent N-phthalimido groups form chains parallel to the b axis. The chains are further stabilized by C—H⋯π inter­actions.
PMCID: PMC3011798  PMID: 21589535
7.  2,2,5,7,8-Penta­methyl­chroman-6-yl 2,3,4,6-tetra-O-acetyl-α-d-glucopyran­oside from synchrotron data 
The crystal structure of the title compound, C28H38O11, solved and refined against synchrotron diffraction data, contains two formula units in the asymmetric unit. In both mol­ecules, the dihydro­pyran ring along with its methyl substituents is disordered and adopts two alternative half-chair conformations. The occupancy of the major conformers of the two mol­ecules refined to 0.858 (5) and 0.523 (5).
PMCID: PMC3052099  PMID: 21522460
8.  2,3,4,6-Tetra-O-acetyl-2-phthalimido-β-d-glucopyran­oside 
In the crystal structure of the title compound, C24H27NO11, a substituted tetra­acetyl glucopyran­oside derivative, weak inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into ribbons propagated in [010]. The d configuration has been attributed on the basis of the synthesis and the β anomer has been determined from the structure.
PMCID: PMC3011788  PMID: 21589578
9.  1-O-Acetyl-3,4,6-tri-O-benzyl-2-C-bromo­methyl-2-de­oxy-α-d-glucopyran­ose 
In the title compound, C30H33BrO6, the pyran­ose ring adopts a chair conformation. Two of the O-benzyl phenyl rings lie almost perpendicular to C/C/C/O plane formed by the ring atoms not attached to these O-benzyl phenyl rings, and form dihedral angles of 85.1 (2) and 64.6 (2)°, while the third O-benzyl phenyl ring is twisted so that it makes a dihedral angle 34.9 (2)° to this C/C/C/O plane. This twist is ascribed to the formation of an S(8) loop stabilized by a weak intra­molecular C—H⋯O hydrogen bond.
PMCID: PMC3588367  PMID: 23476454
10.  Methyl 3-O-α-d-mannopyranosyl β-d-glucopyran­oside tetra­hydrate 
The title compound, C13H24O11·4H2O, forms extended hydrogen-bonded networks. These are present between disaccharides, but not as inter-residue hydrogen bonds, as well as to water mol­ecules that in addition form an inter­molecular chain of hydrogen bonds. The conformation of the disaccharide is described by the glycosidic torsion angles ϕH = −34° and ψH = −5°. Macroscopically, the disaccharide was observed to be hygroscopic.
PMCID: PMC2962246  PMID: 21203328
11.  2-Acetamido-2-de­oxy-3-O-β-d-galactopyranosyl-d-glucose dihydrate 
In the title compound, C14H25NO11·2H2O, the primary hydroxyl group connected to the anomeric C atom of the N-acetyl-β-d-glucopyran­ose residue exhibits positional disorder, with occupancy factors for the α and β anomers of 0.77 and 0.23, respectively. The two torsion angles (Φ and Ψ) and the bridge angle (τ) that describe conformation of the glycosidic linkage between the galactopyran­ose and glucopyran­ose rings are Φ = −81.6 (3)°, Ψ = 118.1 (2)° and τ = 115.2 (2)°. Two water mol­ecules stabilize the mol­ecular packing by forming hydrogen bonds with the saccharide residues.
PMCID: PMC2977301  PMID: 21583488
12.  2,3,4,6-Tetra-O-acetyl-1-O-(4-methoxy­cinnamo­yl)-β-d-glucopyran­ose 
Mol­ecules of the title compound, C24H28O12, are linked by inter­molecular C—H⋯O hydrogen bonds. Bond lengths and angles are normal.
PMCID: PMC2960856  PMID: 21201950
13.  Methyl (2Z)-2-(2-fluoro-4-meth­oxy­benzyl­idene)-5-(4-meth­oxy­phen­yl)-7-methyl-3-oxo-2,3-dihydro-5H-[1,3]thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate 
The asymmetric unit of the title compound, C24H21FN2O5S, consists of two crystallographically independent mol­ecules. In each mol­ecule, the central dihydro­pyrimidine ring is significantly puckered and adopts a conformation which is best described as an inter­mediate between a boat and a screw boat. The least-squares planes of the dihydro­pyrimidine rings are almost coplanar with the fluoro-substituted benzene rings, making dihedral angles of 9.04 (7) and 6.68 (7)°, and almost perpendicular to the meth­oxy-substituted benzene rings with dihedral angles of 89.23 (7) and 88.30 (7)°. In the mol­ecular structure, S(6) ring motifs are formed by C—H⋯O and C—H⋯S hydrogen bonds. In the crystal, mol­ecules are linked into a three-dimensional network by inter­molecular C—H⋯O and C—H⋯F hydrogen bonds. The crystal structure is further stabilized by a C—H⋯π inter­action.
PMCID: PMC3212305  PMID: 22090962
14.  15α,20β-Dihydr­oxy-6β-meth­oxy-6,7-seco-6,20-ep­oxy-1,7-olide-ent-kaur-16-ene 
The title compound, C21H30O6, a natural ent-kaurane diterpenoid, was obtained from the medicinal plant Isodon serra. The five rings in the mol­ecule exhibit the expected cis and trans junctions. The three six-membered rings adopt chair, twist-boat and boat conformations, while two five-membered rings adopt envelope conformations. There are two mol­ecules in the asymmetric unit, related by a non-crystallographic twofold screw axis; the main difference is in the different degrees of distortion of ring B. In the crystal, the mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds, forming chains along the b axis.
PMCID: PMC2984011  PMID: 21580740
15.  {6,6′-Dieth­oxy-2,2′-[2,2-dimethyl­propane-1,3-diylbis(nitrilo­methyl­idyne)]diphenolato}(2-eth­oxy-6-formyl­phenolato)cobalt(III)–ethanol–water (1/1/1) 
The asymmetric unit of the title compound, [Co(C23H28N2O4)(C9H9O3)]·C2H5OH·H2O, comprises one complex mol­ecule, a water mol­ecule of crystallization and an ethanol mol­ecule of crystallization, which is disordered over two positions with a ratio of refined site occupancies of 0.567 (10):0.433 (10). The CoIII ion is in a slightly distorted octa­hedral geometry involving an N2O2 atom set of the tetra­denate Schiff base ligand and two O atoms of 2-eth­oxy-6-formyl­phenolate. The H atoms of the water mol­ecule act as donors in the formation of bifurcated inter­molecular O—H⋯(O,O) hydrogen bonds with the O atoms of the hydr­oxy and eth­oxy groups with R 1 2(5) ring motifs, which may influence the mol­ecular conformation. The crystal structure is further stabilized by inter­molecular O—H⋯O and C—H⋯O inter­actions.
PMCID: PMC2983841  PMID: 21580480
16.  3-{3,5-Bis[(2-but­oxy­eth­oxy)carbon­yl]-2,6-dimethyl-1,4-dihydro­pyridin-4-yl}-1-[(3,4,5-trimeth­oxy­benzo­yl)meth­yl]pyridinium bromide 
In the title salt, C37H51N2O10 +·Br−, the 1,4-dihydro­pyridine (1,4-DHP) ring adopts a slighly puckered boat conformation. The N and opposite C atoms deviate from the least-squares plane calculated through the four other ring atoms by 0.068 (5) and 0.224 (5) Å, respectively. The orientation of both C=O groups is similar (cis with respect to the double bonds of 1,4-DHP. The pyridinium ring has an axial orientation with respect to the1,4-DHP ring and is almost perpendicular to the least-squares plane of the 1,4-DHP ring, making a dihedral angle of 89.2 (3)°. The mol­ecule has a compact shape due to the parallel orientation of the long-chain substituents. One of the but­oxy groups was fond to be disordered (occupancy ratio 0.70:0.30). In the crystal, the bromide anion accepts a weak hydrogen bond from the N—H group of a neighboring 1,4-DHP ring.
PMCID: PMC3588226  PMID: 23476440
17.  Penta­fluoro­phenyl (3R,4R,5S)-5-{[(3R,4R,5S)-5-azido­methyl-3,4-dimeth­oxy-2,3,4,5-tetra­hydro­furan-3-carboxamido]­meth­yl}-3,4-dimeth­oxy-2,3,4,5-tetra­hydro­furan-3-carboxyl­ate 
The title compound, C22H25F5N4O9, is a stable penta­fluoro­phenyl ester inter­mediate in the synthesis of novel homo-oligomeric structures containing branched carbon chains. The structure is epimeric to the previously characterized dimeric penta­fluoro­phenyl ester with stereochemistry (3R,4R,5R), which was synthesized using d-ribose as starting material. The crystal structure of the title mol­ecule removes any ambiguities arising from the relative stereochemistries of the six chiral centres. Two hydrogen bonds, bifurcating from the NH group, stabilize the crystal: one intra­molecular and one inter­molecular, both involving O atoms of the meth­oxy groups. The asymmetric unit contains two independent mol­ecules not related by any pseudo-symmetry operators. The major conformational differences are localized, leading to one mol­ecule being extended compared to the other. The collected crystal was twinned (twin ratio is 0.939:0.061), and the azide group is positionally disordered over two positions in one mol­ecule [occupancy ratio 0.511 (18):0.489 (18)].
PMCID: PMC3009349  PMID: 21588915
18.  Two-dimensional hydrogen-bonded polymers in the crystal structures of the ammonium salts of phen­oxy­acetic acid, (4-fluoro­phen­oxy)acetic acid and (4-chloro-2-methyl­phen­oxy)acetic acid 
The crystal of the isomorphous anhydrous ammonium salts of phen­oxy­acetic acid and (4-fluoro­phen­oxy)acetic acid and that of the hemihydrate ammonium salt of 4-chloro-2-methyl­phen­oxy)acetic acid show two-dimensional layered structures based on conjoined cyclic hydrogen-bonded motifs.
The structures of the ammonium salts of phen­oxy­acetic acid, NH4 +·C8H6O3 −, (I), (4-fluoro­phen­oxy)acetic acid, NH4 +·C8H5FO3 −, (II), and the herbicidally active (4-chloro-2-methyl­phen­oxy)acetic acid (MCPA), NH4 +·C9H8ClO3 −·0.5H2O, (III) have been determined. All have two-dimensional layered structures based on inter-species ammonium N—H⋯O hydrogen-bonding associations, which give core substructures consisting primarily of conjoined cyclic motifs. The crystals of (I) and (II) are isomorphous with the core comprising R 1 2(5), R 1 2(4) and centrosymmetric R 4 2(8) ring motifs, giving two-dimensional layers lying parallel to (100). In (III), the water mol­ecule of solvation lies on a crystallographic twofold rotation axis and bridges two carboxyl O atoms in an R 4 4(12) hydrogen-bonded motif, creating two R 4 3(10) rings, which together with a conjoined centrosymmetric R 4 2(8) ring incorporating both ammonium cations, generate two-dimensional layers lying parallel to (100). No π–π ring associations are present in any of the structures.
PMCID: PMC4257399  PMID: 25552984
crystal structure; phen­oxy­acetic acid salts; MCPA; herbicides; ammonium carboxyl­ates; hydrogen bonding
19.  3-Ethyl-8-meth­oxy-4-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranos­yloxy)quinolin-2(1H)-one 
The structure of the title compound, C26H31NO12, contains an essentially planar quinoline skeleton, with the maximum deviation from the best plane being 0.055 (2) Å, and an oxane ring in a classical chair conformation with the following Cremer and Pople puckering parameters: Q = 0.586 (2) Å, θ = 11.5 (2)° and ϕ = 309.4 (10)°. One acetyl group displays rotational disorder with occupancies of 0.634 (8):0.366 (8). The crystal packing is stabilized by N—H⋯O hydrogen bonds, which link mol­ecules into chains along the a axis. The packing is further stabilized by weak C—H⋯O interactions. The absolute configurations on the carbons in the oxane ring correspond to those of the commercial starting material and are unchanged in the well known mechanism of the Koenigs–Knorr synthesis.
PMCID: PMC2979627  PMID: 21579419
20.  n-Propyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyran­oside 
The title compound [systematic name: (2R,3R,4S,5R,6R)-2-(acet­oxy­meth­yl)-6-propoxytetra­hydro-2H-pyran-3,4,5-triyl triacetate], C17H26O10, was formed by a Koenigs–Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide and n-propanol. The central ring adopts a chair conformation. The crystal does not contain any significant inter­actions such as hydrogen bonds.
PMCID: PMC3569225  PMID: 23424448
21.  (1α,2β,3α,7α,11α,13β)-1,3,11-Triacet­oxy-2,13-bis­(benz­yloxy)-7-hydr­oxy-21-methyl-N,19-secohetisan-19-al 
The title compound (delgradine), C41H43NO12, is a hetisine-type C20-diterpenoid alkaloid, isolated from the roots of Aconitum carmichaeli Debx. In the crystal structure, the mol­ecule assumes an U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The mol­ecule contains eight alicyclic and heterocyclic rings. Cyclo­hexane rings A and B adopt similar chair conformations; the six-membered rings C, D and E form a bicyclo­[2.2.2]octane system with a boat conformation for each six-membered ring, the six-membered heterocyclic ring F has a screw-boat conformation and both of the five-membered rings G and H have envelope conformations. The crystal structure contains inter­molecular O—H⋯O hydrogen bonding.
PMCID: PMC2962025  PMID: 21203114
22.  5,11,17,23-Tetra-tert-butyl-25,27-bis­[2-(4-nitro­phen­oxy)eth­oxy]calix[4]arene-26,28-diol acetonitrile tetra­solvate 
In the crystal structure of the title compound, C60H70N2O10·4CH3CN, the calix[4]arene mol­ecule adopts an open-cone conformation with two intra­molecular O—H⋯O hydrogen bonds. The four benzene rings of the calix[4]arene are twisted to the mean plane defined by four methyl­ene C atoms bridging the benzene rings, with dihedral angles ranging from 57.74 (10) to 65.99 (12)°. Two pendant nitro­phenyl rings are nearly perpendicular to each other, the dihedral angle being 70.9 (3)°. The asymmetric unit of the crystal structure contains four acetonitrile solvent mol­ecules, one of which lies in the calix cavity and makes C—H⋯π inter­actions and another links with the calix[4]arene via C—H⋯O hydrogen bonding. One tert-butyl group is disordered over two sets of sites, with a 0.736 (13):0.264 (13) occupancy ratio.
PMCID: PMC2969685  PMID: 21583190
23.  (E)-1-[2-Hy­droxy-4,6-bis­(meth­oxy­meth­oxy)phen­yl]-3-[3-meth­oxy-4-(meth­oxy­meth­oxy)phen­yl]prop-2-en-1-one 
The title compound, C22H26O9, crystallizes with two independent mol­ecules in the asymmetric unit in which the dihedral angles between the two benzene rings are 21.4 (2) and 5.1 (2)°. An intra­molecular O—H⋯O hydrogen bond occurs in each mol­ecule. Inter­molecular C—H⋯O hydrogen bonds stabilize the crystal structure.
PMCID: PMC3247344  PMID: 22219962
24.  4-(Dimeth­oxy­meth­yl)phenyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyran­oside 
The enanti­omerically pure title compound, C23H30O12, crystallizes in the chiral space group P212121. The O-acetyl­ated-glucopyran­oside moiety adopts a chair conformation. Numerous C—H⋯O inter­actions as well as a C—H⋯π inter­action are present in the crystal structure.
PMCID: PMC3344139  PMID: 22606142
25.  (E)-3-(8-Benz­yloxy-2,3-dihydro-1,4-benzodioxin-6-yl)-1-[2-hy­droxy-4,6-bis­(meth­oxy­meth­oxy)phen­yl]prop-2-en-1-one 
In the title mol­ecule, C28H28O9, the phenol and the benzene rings adjacent to the α,β-unsaturated ketone unit are inclined at 9.15 (13)° to each other. The terminal phenyl ring is oriented with respect to the phenol ring at a dihedral angle of 85.88 (13)°. In the crystal, the methyl­ene C atoms of the dihydro­dioxine ring are disordered over two sites with an occupancy ratio of 0.463 (18):0.537 (18), and both disordered components of the dihydro­dioxine ring adopt twisted-chair conformations. An intra­molecular O—H⋯O hydrogen bond and weak inter­molecular C—H⋯O hydrogen bonds are present in the crystal structure.
PMCID: PMC3100013  PMID: 21754185

Results 1-25 (452097)