scholarly journals Isolation and crystal structure of lawinal

2021 ◽  
Vol 77 (1) ◽  
pp. 75-78
Author(s):  
Virayu Suthiphasilp ◽  
Pornphimol Meesakul ◽  
Christopher Richardson ◽  
Stephen G. Pyne ◽  
Surat Laphookhieo
Keyword(s):  
Crystal Structure ◽  
Natural Product ◽  
Absolute Configuration ◽  
Specific Rotation ◽  
Stereochemical Assignment ◽  
X Ray ◽  
Π Interactions ◽  
Independent Molecules ◽  
The Absolute ◽  
Hydrogen Bonded

The structure of the natural product lawinal [systematic name: (−)-(2S)-5,7-dihydroxy-6-methyl-4-oxo-2-phenylchromane-8-carbaldehyde, C17H14O5] at 150 K is reported. The compound crystallizes with monoclinic (I2) symmetry and with Z′ = 2. The absolute configuration could not be determined reliably from X-ray analysis only. However, our analysis returns the S-configuration at the C-2 position, consistent with previous stereochemical assignment from specific rotation. The independent molecules form into alternating hydrogen-bonded chains with C—H...O=CH intermolecular linkages that run parallel to the crystallographic a axis and are extended into the ac plane by π–π interactions between their phenyl substituents.

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

Absolute configuration determination of theanti-head-to-head photocyclodimer of anthracene-2-carboxylic acid through cocrystallization withL-prolinol

2013 ◽  
Vol 69 (11) ◽  
pp. 1411-1413 ◽  
Author(s):  
Yuko Kawanami ◽  
Hidekazu Tanaka ◽  
Jun-ichi Mizoguchi ◽  
Nobuko Kanehisa ◽  
Gaku Fukuhara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Carboxylic Acid ◽  
Absolute Configuration ◽  
Void Space ◽  
Circular Dichroism Spectra ◽  
The Absolute ◽  
Circular Dichroïsm ◽  
Hydrogen Bonded

The absolute configuration has been established of the enantiopureanti-head-to-head cyclodimer of anthracene-2-carboxylic acid (AC) cocrystallized with L-propinol and dichloromethane [systematic name: (S)-2-(hydroxymethyl)pyrrolidin-1-ium (5R,6S,11R,12S)-8-carboxy-5,6,11,12-tetrahydro-5,12:6,11-bis([1,2]benzeno)dibenzo[a,e][8]annulene-2-carboxylate dichloromethane monosolvate], C5H12NO+·C30H19O4−·CH2Cl2. In the crystal structure, the AC dimer interacts with L-prolinol through a nine-membered hydrogen-bonded ring [R22(9)], while the dichloromethane molecule is incorporated to fill the void space. The absolute configuration determined in this study verifies a recent assignment made by comparing theoreticalversusexperimental circular dichroism spectra.

(1R,4S,8R,12S,13S,14R,16S,19R)-14-Hydroxy-7,7-dimethyl-17-methylene-2,9,18-trioxo-3,10-dioxapentacyclo[14.2.1.01,13.04,12.08,12]nonadec-19-yl acetate

2007 ◽  
Vol 63 (11) ◽  
pp. o4439-o4439
Author(s):  
Hao Shi
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Absolute Configuration ◽  
Title Compound ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Asymmetric Unit ◽  
Compound C ◽  
Independent Molecules ◽  
The Absolute

The title compound, C22H26O8, prepared from the natural diterpenoid Macrocalyxin J, is built up from five fused rings. Cyclohenane ring A adopts a chair conformation, ring B exists in a screw-boat conformation and ring C adopts a boat conformation; the two five membered rings adopt envelope conformations. Two unique molecules are present in the asymmetric unit; both independent molecules have the same absolute configuration, the absolute configuration being deduced from the chirality of Macrocalyxin A, which was isolated from the same plant (i.e. Rabdosia macrocalyx) as Macrocalyxin J. The crystal structure displays intermolecular O—H...O hydrogen bonds.

scholarly journals Crystal structure of 5-[(benzoyloxy)methyl]-5,6-dihydroxy-4-oxocyclohex-2-en-1-yl benzoate

2020 ◽  
Vol 76 (7) ◽  
pp. 1096-1100
Author(s):  
Theerachart Leepasert ◽  
Patchreenart Saparpakorn ◽  
Kittipong Chainok ◽  
Tanwawan Duangthongyou
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Natural Product ◽  
Dihedral Angle ◽  
Absolute Configuration ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ring Form

The crystal structure of the natural product zeylenone, C21H18O7, was confirmed by single-crystal X-ray diffraction. The crystal structure has three chiral centers at positions C1, C5 and C6 of the cyclohexanone ring, but the absolute configuration could not be determined reliably. The methyl benzoate and benzoyloxy substituents at positions C1 and C5 of the cyclohexenone ring are on the same side of the ring with the dihedral angle between their mean planes being 16.25 (10)°. These rings are almost perpendicular to the cyclohexenone ring. The benzoate groups and two hydroxyl groups on the cyclohexenone ring form strong hydrogen bonds to consolidate the crystal structure. In addition, weak C—H...O hydrogen bonds also contribute to the packing of the structure.

scholarly journals Synthesis and crystal structure of (±)-Goniotamirenone C

2020 ◽  
Vol 76 (11) ◽  
pp. 1728-1731
Author(s):  
Pornphimol Meesakul ◽  
Christopher Richardson ◽  
Surat Laphookhieo ◽  
Stephen G. Pyne
Keyword(s):  
Crystal Structure ◽  
Structural Analysis ◽  
Natural Product ◽  
The Other ◽  
Independent Molecule ◽  
Synthesis And Crystal Structure ◽  
Previous Assignment ◽  
Independent Molecules ◽  
Hydrogen Bonded

The structure of the racemic version of the natural product Goniotamirenone C [racemic anti-6-(2-chloro-1-hydroxy-2-phenylethyl)-2H-pyran-2-one, C13H11ClO3] at 150 K is reported. The compound crystallizes with monoclinic (P21/n) symmetry and with Z′ = 2. One independent molecule is ordered while the other independent molecule exhibits an interesting whole-molecule enantiomeric disorder with occupancies of 0.846 (4) and 0.154 (4). The independent molecules are hydrogen bonded with –OH...O=C linkages into chains that run parallel to the a axis. This structural analysis corrects our previous assignment as the syn isomer [Meesakul et al. (2020). Phytochemistry, 171, 112248–112255].

scholarly journals Crystal structure of (1S,2R,4S)-1-[(morpholin-4-yl)methyl]-4-(prop-1-en-2-yl)cyclohexane-1,2-diol

2015 ◽  
Vol 71 (1) ◽  
pp. 79-81 ◽  
Author(s):  
Rachid Outouch ◽  
Saadia Oubaassine ◽  
Mustapha Ait Ali ◽  
Larbi El Firdoussi ◽  
Anke Spannenberg
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Absolute Configuration ◽  
Title Compound ◽  
Chair Conformation ◽  
Asymmetric Unit ◽  
Compound C ◽  
Synthetic Procedure ◽  
Independent Molecules ◽  
The Absolute

The asymmetric unit of the title compound, C14H25NO3, contains two independent molecules with similar geometry. The morpholine and cyclohexane rings of both molecules adopt a chair conformation. Intramolecular O—H...N hydrogen bonds are observed. In the crystal, molecules are linked by O—H...O hydrogen bonds into chains parallel to the [101] direction. The chains are further connected through C—H...O hydrogen bonds forming undulating layers parallel to the (-101) plane. The absolute configuration was assigned by reference to an unchanging chiral centre in the synthetic procedure.

Crystal structure of aristoserratine

1983 ◽  
Vol 36 (5) ◽  
pp. 1037 ◽  
Author(s):  
IRC Bick ◽  
MA Hai ◽  
VA Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Circular Dichroism ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Circular Dichroism Spectrum ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
The Absolute ◽  
Circular Dichroïsm

The crystal structure of the alkaloid aristoserratine,* C20H24N2O, has been determined by single-crystal X-ray diffraction methods at 295 K, the structure being refined to a residual of 0.034 for 1107 independent 'observed' reflections. Crystals are monoclinic, P21, a 14.836(5), b 8.568(3), c 6.633(3) �, β 98.05(3)�, Z 2. The relative configuration is established and, by inference, by comparison of the circular dichroism spectrum with that of aristoteline, the absolute configuration is assigned.

scholarly journals Crystal structure of (R)-N-benzyl-1-phenylethanaminium (R)-4-chloromandelate

2014 ◽  
Vol 70 (12) ◽  
pp. o1223-o1224
Author(s):  
Yangfeng Peng ◽  
Sohrab Rohani ◽  
Paul D. Boyle ◽  
Quan He
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Absolute Configuration ◽  
Three Dimensional ◽  
Resonant Scattering ◽  
Π Interactions ◽  
Two Component ◽  
Phenyl Rings ◽  
The Absolute ◽  
Molecular Salt

The absolute configuration of the title molecular salt, C15H18N+·C8H6ClO3−, has been confirmed by resonant scattering. In the (R)-N-benzyl-1-phenyl-ethylammonium cation, the phenyl rings are inclined to one another by 44.65 (7)°. In the crystal, the (R)-4-chloromandelate anions are linkedviaO—H...O hydrogen bonds and bridged by N—H...O hydrogen bonds involving the cations, forming chains along [010]. There are C—H...O hydrogen bonds present within the chains, which are linkedviaC—H...π interactions and a short Cl...Cl interaction [3.193 (1) Å] forming a three-dimensional framework. The structure was refined as a two-component inversion twin giving a Flack parameter of 0.05 (4).

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