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Crystal structure of 1,2,3,4-di-O-methyl-ene-α-d-galacto-pyran-ose.

ABSTRACT: The title compound, C8H12O6, was synthesized by de-acetyl-ation of 6-acetyl-1,2,3,4-di-O-methyl-ene-α-d-galactose with sodium methoxide. The central part of the mol-ecule consists of a six-membered C5O pyran-ose ring with a twist-boat conformation. Both fused dioxolane rings adopt an envelope conformation with C and O atoms as the flap. In the crystal, O-H⋯O and C-H⋯O hydrogen bonds are present between adjacent mol-ecules, generating a three-dimensional network.

SUBMITTER: Tiritiris I

PROVIDER: S-EPMC4719923 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Crystal structure of 1,2,3,5-di-O-methyl-ene-?-d-xylo-furan-ose.

Project description:The title compound, C7H10O5, was synthesized by reaction of d-xylose with paraformaldehyde. In the crystal, the central part of the mol-ecule consists of a five-membered C4O ring with an envelope conformation, with the methine C atom adjacent to the O atom being the flap. The protected O atoms of both cyclic acetal groups are oriented so that the four chiral C atoms of the furan-ose part show an R configuration. C-H?O hydrogen bonds are present between adjacent mol-ecules, generating a three-dimensional network.

| S-EPMC4645044 | biostudies-literature

6-[Bis(ethoxycarbonyl)methyl]-6-deoxy-1,2;3,4-di-O-isopropyl-idene-d-galacto-pyran-ose.

Project description:The title compound, C(19)H(30)O(9), was prepared by substitution at the C6 position in 1,2;3,4-di-O-isopropyl-idene-6-O-trifluoro-methane-sulfonyl-d-galactose using sodium eth-oxy-malonate in dimethyl-formamide. The conformation is skew-boat (0)S(2), slightly distorted towards boat B(2,5). The inflexible pyran-ose structure makes the title compound a suitable inter-mediate for further synthetic work by keeping stereogenic carbon atoms safe from inversion. Several short intra-molecular C-H? O contacts may stabilize the conformation of the mol-ecule. Inter-molecular C-H?O inter-actions also occur.

| S-EPMC3011695 | biostudies-literature

Crystal structure of methyl α-l-rhamno-pyranosyl-(1→2)-α-l-rhamno-pyran-oside monohydrate.

Project description:The title compound, C13H24O9·H2O, a structural model for part of bacterial O-anti-gen polysaccharides from Shigella flexneri and Escherichia coli, crystallizes with four independent disaccharide mol-ecules and four water mol-ecules in the asymmetric unit. The conformation at the glycosidic linkage joining the two rhamnosyl residues is described by the torsion angles φH of 39, 30, 37 and 37°, and ψH of -32, -35, -31 and -32°, which are the major conformation region known to be populated in an aqueous solution. The hexo-pyran-ose rings have the 1 C 4 chair conformation. In the crystal, the disaccharide and water mol-ecules are associated through O-H⋯O hydrogen bonds, forming a layer parallel to the bc plane. The layers stack along the a axis via hydro-phobic inter-actions between the methyl groups.

| S-EPMC6658941 | biostudies-literature

Crystal structure of the di-Mannich base 4,4'-di-chloro-3,3',5,5'-tetra-methyl-2,2'-[imidazolidine-1,3-diylbis(methyl-ene)]diphenol.

Project description:The title compound, C21H26Cl2N2O2, was prepared in a solvent-free microwave-assisted synthesis, and crystallizes in the ortho-rhom-bic space group Pna21. The imidazolidine ring adopts an envelope conformation and its mean plane is almost perpendicular to the two pendant aromatic rings [dihedral angles = 84.61?(9) and 86.54?(9)°]. The mol-ecular structure shows the presence of two intra-molecular O-H?N hydrogen bonds between the phenolic hy-droxy groups and imidazolidine N atoms. The two 3-chloro-6-hy-droxy-2,4-di-methyl-benzyl groups are located in a cis orientation with respect to the imidazolidine fragment. As a result, the lone pairs of electrons on the N atoms are presumed to be disposed in a syn conformation. This is therefore the first example of an exception to the 'rabbit-ears' effect in such 2,2'-[imidazolidine-1,3-diylbis(methyl-ene)]diphenol derivatives.

| S-EPMC4350744 | biostudies-literature

Crystal structure of 3-de-oxy-3-nitro-methyl-1,2;5,6-di-O-iso-propyl-idene-?-d-allo-furan-ose.

Project description:The title compound, C13H21NO7 {systematic name: (3aR,5S,6R,6aR)-5-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2,2-dimethyl-6-(nitro-meth-yl)tetra-hydro-furo[2,3-d][1,3]dioxole}, consists of a substituted 2,2-di-methyl-tetra-hydro-furo[2,3-d][1,3]dioxolane skeleton. The furan-ose ring A adopts a (o)T 4 conformation. The fused dioxolane ring B and the substituent dioxolane ring C also have twisted conformations. There are no strong hydrogen bonds in the crystal structure: only weak C-H?O contacts are present, which link the mol-ecules to form a three-dimensional structure.

| S-EPMC4778814 | biostudies-literature

5-Methyl-1,3-phenyl-ene bis-[5-(di-methyl-amino)-naphthalene-1-sulfonate]: crystal structure and DFT calculations.

Project description:The title compound, C31H30N2S2O6, possesses crystallographically imposed twofold symmetry with the two C atoms of the central benzene ring and the C atom of its methyl substituent lying on the twofold rotation axis. The two dansyl groups are twisted away from the plane of methyl-phenyl bridging unit in opposite directions. The three-dimensional arrangement in the crystal is mainly stabilized by weak hydrogen bonds between the sulfonyl oxygen atoms and the hydrogen atoms from the N-methyl groups. Stacking of the dansyl group is not observed. From the DFT calculations, the HOMO-LUMO energy gap was found to be 2.99?eV and indicates n??* and ???* transitions within the mol-ecule.

| S-EPMC6659316 | biostudies-literature

Crystal structure of 6-de-oxy-α-l-psico-furan-ose.

Project description:The title compound, C6H12O5, was crystallized from an aqueous solution of 6-de-oxy-l-psicose (6-de-oxy-l-allulose, (3S,4S,5S)-1,3,4,5-tetra-hydroxy-hexan-2-one), and the mol-ecule was confirmed as α-furan-ose with a (3) T 4 (or E 4) conformation, which is a predominant tautomer in solution. This five-membered furan-ose ring structure is the second example in the field of the 6-de-oxy-ketohexose family. The cell volume of the title compound [742.67 (7) Å(3), Z = 4 at room temperature] is only 1.4% smaller than that of β-d-psico-pyran-ose, C6H12O6 (753.056 Å(3), Z = 4 at room temperature).

| S-EPMC4719940 | biostudies-literature

Crystal structure of 1,2-di-benzoyl-ace-naphthyl-ene.

Project description:The title mol-ecule, C26H16O2, crystallizes as a mol-ecular crystal with no strong inter-molecular inter-actions (the shortest C-H⋯O contact is longer than 3.4 Å). Two flat ace-naphthyl-ene groups of neigboring 1,2-di-benzoyl-ace-naphthyl-ene mol-ecules are related by a crystallographic center of symmetry and are stacked with the distance between their mean planes of 3.37 (1) Å, apparently making an optimal close packing for these bulky aromatic moieties. Both carbonyl groups are oriented towards the same side of the planar ace-naphthyl-ene. The angles between the flat ace-naphthyl-ene group and the benzoyl groups are 62.6 (1) and 57.8 (1)°. Because rotation of the benzoyl groups is sterically hindered, we expect that the mol-ecules will remain locked in this 'pseudo-cis' orientation in solution. As a result, reduction of 1,2-di-benzoyl-ace-naphthyl-ene at low temperature with sodium di-thio-nite yields the cis-isomer of 1,2-dibenzoyl-1,2-di-hydro-ace-naphthyl-ene, which is sterically favorable. This isomer is thermodynamically less favorable than the trans isomer, but it converts to the more stable isomer only on long-term heating (Greenberg & Schenendorf (1980 ▸).

| S-EPMC4518958 | biostudies-literature

Crystal structure of 4-nitro-phenyl 6-<i>O</i>-ethyl-β-d-galacto-pyran-oside monohydrate.

Project description:The synthesis and crystal structure of the title compound, C14H19NO8·H2O, prepared in three steps from 6-O-ethyl-1,2;3,4-di-O-iso-propyl-idene-α-d-galacto-pyran-ose using protecting-group strategies employed in carbohydrate chemistry, is reported. The asymmetric unit consists of a single galactoside mol-ecule, in which the pyran-oid ring has a 4C1 conformation and the 4-nitro-phenyl moiety is essentially planar. In the crystal, each carbohydrate is surrounded by other d-galactose residues and water mol-ecules, linked by O-H⋯O hydrogen bonds involving all hy-droxy groups, giving a two-dimensional substructure lying parallel to (100) and extended into three dimensions by C-H⋯O inter-actions.

| S-EPMC5382630 | biostudies-literature

Crystal structure of isobutyl 4-(2-chloro-phen-yl)-5-cyano-6-{(E)-[(di-methyl-amino)-methyl-idene]amino}-2-methyl-4H-pyran-3-carboxyl-ate.

Project description:In the title compound, C21H24ClN3O3, the dihedral angle between the pyran ring (r.m.s. deviation = 0.037?Å) and the chloro-benzene ring is 88.56?(14)°. In the crystal, the mol-ecules are linked by C-H?O inter-actions, generating C(7) (001) chains.

| S-EPMC4384599 | biostudies-literature

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