Crystal Structure Of Methyl Research Articles

Conformational disorder in the crystal structure of methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside (methyl β-chitobioside) methanol monosolvate.

Methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside (methyl β-chitobioside), (IV), crystallizes from aqueous methanol at room temperature to give a structure (C17H30N2O22·CH3OH) containing conformational disorder in the exocyclic hydroxymethyl group of one of its βGlcNAc residues. As observed in other X-ray structures of disaccharides containing β-(1→4) O-glycosidic linkages, inter-residue hydrogen bonding between O3H of the βGlcNAc bearing the OCH3 aglycone and O5 of the adjacent βGlcNAc is observed based on the 2.79 Å internuclear distance between the O atoms. The structure of (IV) was compared to that determined previously for 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranose (β-chitobiose), (III). The O-glycosidic linkage torsion angles, phi (φ) and psi (ψ), in (III) and (IV) differ by 6-8°. The N-acetyl side chain conformation in (III) and (IV) shows some context dependence, with the C1-C2-N-Ccar torsion angle 10-15° smaller for the βGlcNAc residue involved in the internal O-glycosidic linkage. In (IV), conformational disorder is observed in the exocyclic hydroxymethyl (-CH2OH) group in the βGlcNAc residue bearing the OCH3 aglycone, and a fitting of the electron density indicates an approximate 50:50 distribution of the gauche-gauche (gg) and gauche-trans (gt) conformers in the lattice. Similar behavior is not observed in (III), presumably due to the different packing structure in the vicinity of the -CH2OH substituent that affects its ability to hydrogen bond to proximal donors/acceptors. Unlike (IV), a re-examination of the previously reported electron density of (III) revealed conformational disorder in the N-acetyl side chain attached to the reducing-end βGlcNAc residue caused by rotation about the C2-N bond.

Synthesis, characterization and crystal structure of methyl 2-(2-oxo-2H-chromen-4-yl-amino)-benzoate.

Methyl 2-(2-oxo-2H-chromen-4-yl-amino)-benzoate, C17H13NO4 (1), was pre-pared by condensation between 4-hy-droxy-coumarin and methyl 2-amino-benzoate. It crystallizes in the ortho-rhom-bic space group Pca21 at 300 K. The mol-ecule of compound 1 consists of the 2H-chromen-2-one part connected by an amine moiety (-NH-) to the methyl benzoate ring. The supra-molecular array is formed by hydrogen bonds between the aromatic ring and the O atoms of the lactone and ester portions. The structural details match the spectroscopic data acquired from NMR and IR spectroscopy.

Crystal Structure of Methyl 3-O-α-d-Glucopyranosyl 2-Acetamido-2-Deoxy-α-d-Galactopyranoside Hydrate

Methyl 3-O-α-d-glucopyranosyl 2-acetamido-2-deoxy-α-d-galactopyranoside as a monohydrate, C15H27NO11·H2O, crystallizes in space group P212121, with four molecules in the unit cell. It constitutes the methyl glycoside of the carbohydrate part of the teichoic acid type polysaccharide from Micrococcus sp. A1, in which the disaccharides are joined through phosphodiester linkages. The conformation of the disaccharide is described by the glycosidic torsion angles ϕ = − 31° and ψ = + 1°, and the hydroxymethyl groups of the constituent monosaccharides are present in the gg and gt conformations for the sugar residues having the gluco- and galacto-configuration, respectively. For the N-acetyl group at C2 of the galactosamine residue the torsion angle τH = 147°, i.e., the amide proton has an antiperiplanar relationship to H2 of the sugar ring. The structure shows extensive hydrogen bonding along the a-direction, including the water molecule, and forms sheets with hydrophilic interactions within the sheets as a result of hydrogen bonding between disaccharides as well as hydrophobic interactions between the sheets, in particular, amongst methyl groups of the N-acetyl group of the α-d-GalpNAc residue in the disaccharides.Graphical The structure of the title disaccharide as a monohydrate, C15H27NO11·H2O, which shows extensive hydrogen bonding as well as hydrophobic interactions, was determined from minute crystals using synchrotron radiation and verified by solid state DFT calculations using plane waves.

The crystal structure of methyl 4-(1H-naphtho[1,8-de][1,3,2]diazaborinin-2(3H)-yl)benzoate, C18H15BN2O2

Abstract C18H15BN2O2, monoclinic, P21/c (no. 14), a = 6.8522(9) Å, b = 8.4333(11) Å, c = 13.1908(18) Å, β = 95.880(5)°, V = 758.24(17) Å3, Z = 2, R gt (F) = 0.0381, wR ref (F 2) = 0.1068, T = 193 K. CCDC no.: 2045109

Computational investigations, Hirshfeld surface analysis, interaction energy calculations, and energy framework crystal structure of methyl 2-amino-5-hydroxybenzoate

The title compound with the molecular formula C8H9NO3 is synthesized by refluxing 2-amino-5-hydroxybenzoic acid in methanol. The molecular structure of the compound is determined by single crystal X-ray diffraction. Methyl 2-amino-5-hydroxybenzoate crystallizes in the orthorhombic space group P212121 with a = 4.973(2) Å, b = 10.923(5) Å, c = 14.074(6) Å, Z = 4 and V = 764.4(6) Å3. DFT is used to compute HOMO—LUMO energy levels, to predict the reactivity of substituents (NH2 and OH), and to determine the nucleophilic character of these two groups. The orientation and nature of substituents on benzene favors the formation of a stable six-membered ring via hydrogen bonding which plays a key role in the properties of the investigated compound. The natural bond orbital (NBO) population analysis demonstrates that the hyperconjugative effect between the donor lone pairs located on the carbonyl oxygen atom and the N—H group, via the lp O → σ*(N—H) 1,6-remote interaction, is responsible for the preferred conformation. The molecular electrostatic potential (MEP) surface shows the electrical neutrality in the molecule. To get an insight to the intermolecular interactions in the crystal a Hirshfeld surface analysis is also carried out.

Glycosidic linkage, N-acetyl side-chain, and other structural properties of methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-β-D-mannopyranoside monohydrate and related compounds.

The crystal structure of methyl 2-acetamido-2-deoxy-β-D-glycopyranosyl-(1→4)-β-D-mannopyranoside monohydrate, C15H27NO11·H2O, was determined and its structural properties compared to those in a set of mono- and disaccharides bearing N-acetyl side-chains in βGlcNAc aldohexopyranosyl rings. Valence bond angles and torsion angles in these side chains are relatively uniform, but C-N (amide) and C-O (carbonyl) bond lengths depend on the state of hydrogen bonding to the carbonyl O atom and N-H hydrogen. Relative to N-acetyl side chains devoid of hydrogen bonding, those in which the carbonyl O atom serves as a hydrogen-bond acceptor display elongated C-O and shortened C-N bonds. This behavior is reproduced by density functional theory (DFT) calculations, indicating that the relative contributions of amide resonance forms to experimental C-N and C-O bond lengths depend on the solvation state, leading to expectations that activation barriers to amide cis-trans isomerization will depend on the polarity of the environment. DFT calculations also revealed useful predictive information on the dependencies of inter-residue hydrogen bonding and some bond angles in or proximal to β-(1→4) O-glycosidic linkages on linkage torsion angles φ and ψ. Hypersurfaces correlating φ and ψ with the linkage C-O-C bond angle and total energy are sufficiently similar to render the former a proxy of the latter.

Conformational analysis of the disaccharide methyl α-D-mannopyranosyl-(1→3)-2-O-acetyl-β-D-mannopyranoside monohydrate.

The crystal structure of methyl α-D-mannopyranosyl-(1→3)-2-O-acetyl-β-D-mannopyranoside monohydrate, C15H26O12·H2O, (II), has been determined and the structural parameters for its constituent α-D-mannopyranosyl residue compared with those for methyl α-D-mannopyranoside. Mono-O-acetylation appears to promote the crystallization of (II), inferred from the difficulty in crystallizing methyl α-D-mannopyranosyl-(1→3)-β-D-mannopyranoside despite repeated attempts. The conformational properties of the O-acetyl side chain in (II) are similar to those observed in recent studies of peracetylated mannose-containing oligosaccharides, having a preferred geometry in which the C2-H2 bond eclipses the C=O bond of the acetyl group. The C2-O2 bond in (II) elongates by ∼0.02 Å upon O-acetylation. The phi (φ) and psi (ψ) torsion angles that dictate the conformation of the internal O-glycosidic linkage in (II) are similar to those determined recently in aqueous solution by NMR spectroscopy for unacetylated (II) using the statistical program MA'AT, with a greater disparity found for ψ (Δ = ∼16°) than for φ (Δ = ∼6°).

Crystal structure of methyl 2,7,7-trimethyl-4-(3-methylthiophen-2-yl)-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C19H23NO3S

Abstract C19H23NO3S, monoclinic, P21/n (no. 14), a = 9.0403(15) Å, b = 18.213(3) Å, c = 11.1889(19) Å, β = 107.964(2)°, V = 1752.4(5) Å3, Z = 4, R gt(F) = 0.0498, wR ref(F 2) = 0.1536, T = 296(2) K.

Crystal structure of methyl 4-(4-isopropylphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydro-quinoline-3-carboxylate, C23H29NO3

Abstract C23H29NO3, monoclinic, P21/n (no. 14), a = 9.531(5) Å, b = 19.245(11) Å, c = 11.902(7) Å, β = 107.003(10)°, Z = 4, V = 2088(2) Å3, R gt(F) = 0.0525, wR ref(F 2) = 0.1512, T = 296 K.

Crystal structure of methyl 4-(3-phenoxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C26H27NO4

Abstract C26H27NO4, monoclinic, P21/c (no. 14), a = 12.034(4) Å, b = 15.247(5) Å, c = 12.991(4) Å, β = 115.379(6)°, V = 2153.6(12) Å3, Z = 4, R gt(F) = 0.0531, wR ref(F 2) = 0.1447, T = 296 K.

Crystal structure of methyl 4-(4-hydroxy-3-nitrophenyl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C18H18N2O6

Abstract C18H18N2O6, monoclinic, P21/n (no. 14), a = 7.4809(14) Å, b = 13.082(2) Å, c = 16.870(3) Å, β = 93.440(4)°, V = 1648.0(5) Å3, Z = 4, R gt(F) = 0.0433, wR ref(F 2) = 0.1279, T = 296(2) K.

Mol-ecular and crystal structure of methyl 4-methyl-2,2-dioxo-1H-2λ6,1-benzo-thia-zine-3-carboxyl-ate.

The title compound, C11H11NO4S, possesses weak analgesic properties and is a source compound for the synthesis of highly active analgesic and anti-inflammatory compounds. The benzo-thia-zine ring adopts a conformation intermediate between twist-boat and sofa. The ester substituent is turned towards the endocyclic double bond because of steric repulsion. In the crystal, the mol-ecules form columns along the [001] direction, bound by N-H⋯O hydrogen bonds and stacking inter-actions.

Crystal structure of methyl 2-methyl-4-(3-methoxyphenyl)-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C19H21NO4

Abstract C19H21NO4, monoclinic, C2/c (no. 15), a = 17.349(5) Å, b = 7.354(2) Å, c = 25.757(7) Å, β = 97.637(5)°, V = 3257.1(16) Å3, Z = 8, R gt(F) = 0.0444, wR ref(F 2) = 0.1141, T = 296(2) K.

Crystal structure of methyl 4-(3,5-ditrifluoromethylphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate — water (2/1), C22H21F6NO3

Abstract C22H21F6NO3, monoclinic, C2/c (no. 15), a = 14.849(4) Å, b = 10.497(3) Å, c = 28.694(7) Å, β = 97.682(5)°, V = 4432(2) Å3, Z = 4, R gt(F) = 0.0736, wR ref(F 2) = 0.2405, T = 293(2) K.

Crystal structure of methyl 4-(4-bromophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate, C20H22BrNO3

Abstract C20H22BrNO3, monoclinic, P21/n (no. 14), a = 9.597(2) Å, b = 18.236(5) Å, c = 11.640(3) Å, β = 111.355(5)°, V = 1897.3(8) Å3, Z = 4, R gt(F) = 0.0497, wR ref(F 2) = 0.1240, T = 296(2) K.

Crystal structure of methyl 4-(3-cyanophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydro-quinoline-3-carboxylate, C21H22N2O3

Abstract C21H22N2O3, orthorhombic, Pbcn (no. 60), a = 15.093(2) Å, b = 13.896(2) Å, c = 17.501(2) Å, V = 3670.5(8) Å3, Z = 8, R gt(F) = 0.0446, wR ref(F 2) = 0.1208, T = 293(2) K.

Synthesis and crystal structure of methyl 3-(3-hy-droxy-3-phenyl-prop-2-eno-yl)benzoate.

The title compound, C17H14O4, was synthesized under mild conditions and characterized by various analytical techniques. Combined NMR and X-ray diffraction data show that the substance exists exclusively in the enol tautomeric form. An intra-molecular ⋯O=C-C=C-OH⋯ hydrogen bond is present in the mol-ecular structure. The analysis of the difference density map disclosed two adjacent positions of a disordered hydrogen atom taking part in this hydrogen bond, indicating the presence of two enol tautomers in the crystal. The enol mol-ecules are assembled through numerous C-H⋯π and π-π as well as weak C(ar-yl)-H⋯O inter-actions, thus forming a dense crystal packing. The obtained substance was also studied by UV-Vis spectroscopy and cyclic voltammetry.

Crystal structure of methyl 10-(pyridin-4-yl)-anthracene-9-carboxylate, C21H15NO2

Abstract C21H15NO2, orthorhombic, Aba2 (no. 41), a = 22.149(2) Å, b = 13.2899(12) Å, c = 10.6679(10) Å, V = 3140.2(5) Å3, Z = 8, R gt(F) = 0.0418, wR ref(F 2) = 0.0953, T = 296(2) K.

The crystal structure of methyl N-(4-bromophenyl)carbamate, C8H8BrNO2

Abstract C8H8BrNO2, orthorhombic, Pbca (no. 61), a = 10.1313(3) Å, b = 8.5416(4) Å, c = 20.4597(7) Å, V = 1770.53(12) Å3, Z = 8, R gt(F) = 0.0394, wR ref(F 2) = 0.1214, T = 296 K.

Crystal structure of methyl (E)-2-(4-(diethylamino)-2-hydroxybenzylidene)hydrazine-1-carboxylate, C13H19N3O3

Abstract C13H19N3O3, monoclinic, P21/c (no. 14), a = 11.594(5) Å, b = 11.311(5) Å, c = 11.688(5) Å, β = 117.347(19)°, V = 1361.4(10) Å3, Z = 4, R gt(F) = 0.0479, wR ref(F 2) = 0.1630, T = 296 K.