Crystal Structure and Conformation of Ring A of 2β-Bromo-19β,28-epoxy-18α-oleanan-3-one

1993 ◽  
Vol 58 (11) ◽  
pp. 2737-2744 ◽  
Author(s):  
Jiří Novotný ◽  
Jaroslav Podlaha ◽  
Jiří Klinot
Keyword(s):  
Crystal Structure ◽  
Opposite Direction ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Form Ring ◽  
Twist Boat

The crystal structure of β-bromo-19β,28-epoxy-18α-oleanan-3-one was elucidated. The crystal is orthorhombic, P212121, a = 9.686(1), b = 14.355(2), c = 19.687(4) Å, Z = 4, R = 0.042 for 2 410 observed reflections. Rings B, C, D and E adopt the chair conformation, the five membered ether cycle in ring E occurs in the envelope form. Ring A takes the twist-boat conformation turned towards the classical boat with C2 and C5 in the stem-stern position, in contrast to the conformation in solution, which is turned in the opposite direction towards the classical boat with C3 and C10 in the stem-stern positions.

scholarly journals Crystal structure of 16-hydroxy-4,4,10,13,14-pentamethyl-17-(6-methylhept-5-en-2-yl)-4,5,6,9,10,11,12,13,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-3(2H)-one

2015 ◽  
Vol 71 (7) ◽  
pp. o464-o465 ◽  
Author(s):  
Jun-Jun Ge ◽  
Pian Chen ◽  
Xiao-Xia Ye
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Chair Conformation ◽  
Membered Ring ◽  
Boat Conformation ◽  
Carbonyl Groups ◽  
Compound C ◽  
Cyclohexene Ring ◽  
Supramolecular Chains ◽  
Twist Boat

The title compound, C30H48O2, contains a fused four-ring triterpenoid system. In the molecule, the two cyclohexane rings adopt a chair conformation and a twist boat conformation, respectively, the central cyclohexene ring adopts a half-chair conformation whereas the five membered ring adopts an envelope conformation. In the crystal, O—H...O hydrogen bonds between the hydroxy and carbonyl groups of adjacent molecules link the molecules into supramolecular chains propagating along theb-axis direction.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

scholarly journals Unusual formation of (E)-11-(aminomethylene)-8,9,10,11-tetrahydropyrido[2′,3′:4,5]pyrimido[1,2-a]azepin-5(7H)-one and its crystal structure

2017 ◽  
Vol 73 (10) ◽  
pp. 1497-1500
Author(s):  
Khamid U. Khodjaniyazov ◽  
Utkir S. Makhmudov ◽  
Kambarali K. Turgunov ◽  
Burkhon Z. Elmuradov
Keyword(s):  
Crystal Structure ◽  
Structural Analysis ◽  
Aqueous Ammonia ◽  
Boat Conformation ◽  
X Ray ◽  
First Time ◽  
Twist Boat ◽  
Unusual Formation

Selective C-formylation of 8,9,10,11-tetrahydropyrido[2′,3′:4,5]pyrimido[1,2-a]-azepin-5(7H)-one has been studied for the first time. It was revealed that formylation proceeds by the formation of an intermediate salt, which due to the re-amination process on treatment with aqueous ammonia transformed into the corresponding (E)-11-(aminomethylene)-8,9,10,11-tetrahydropyrido[2′,3′:4,5]-pyrimido[1,2-a]azepin-5(7H)-one, C13H14N4O, as anE-isomer. Formylation was carried out by Vilsmeier–Haack reagent and the structure of the synthesized compound was confirmed by X-ray structural analysis, spectroscopic and LC–MS methods. In the molecule, the seven-membered pentamethylene ring adopts a twist-boat conformation.

The conformation of (1S,3S,4R)- 1,3,8-Tribromo-p-menthan-2-one

1983 ◽  
Vol 36 (5) ◽  
pp. 1043 ◽  
Author(s):  
RM Carman ◽  
E Horn ◽  
CHL Kennard ◽  
G Smith ◽  
MR Snow ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
A Cell ◽  
Twist Boat

The crystal structure of (1S,3S,4R)-1,3,8-tribromo-p-menthan-2-one has been determined from X-ray diffraction data and refined to a final residual of 0.075 for 635 'observed' reflections. Crystals are orthorhombic, of space group P212121 with four molecules in a cell of dimensions a 15.248(3), b 12.189(3), c 7.201(2) �. The analysis confirms that the molecule exists in a distorted twist-boat conformation.

(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.

The X-Ray Crystal Structure and Photochemistry of 22-α-Hydroxystictan-3-One; a Triterpenoid Keto Alcohol From Pseudocyphellaria Species

1988 ◽  
Vol 41 (1) ◽  
pp. 143 ◽  
Author(s):  
AL Wilkins ◽  
EM Goh
Keyword(s):  
Crystal Structure ◽  
Chair Conformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photochemical Rearrangement ◽  
Twist Boat

The crystal structure of 22α-hydroxystictan-3-one has been determined by X-ray diffraction. Rings A and B of this keto alcohol have been shown to adopt twist boat conformations. Despite the presence of the twist boat ring A system photochemical rearrangement of the keto alcohol proceeds to give 3,4-secostictane derivatives analogous to those afforded by other 3-oxo-4,4-dimethyl steroids and triterpenoids in which ring A adopts a flattened chair conformation.

The twist-boat conformation in a gallium-arsenic six-membered ring: crystal structure of [(Me3SiCH2)2AsGaBr2]3

1988 ◽  
Vol 354 (3) ◽  
pp. 287-292 ◽  
Author(s):  
Richard L. Wells ◽  
Andrew P. Purdy ◽  
Andrew T. McPhail ◽  
Colin G. Pitt
Keyword(s):  
Crystal Structure ◽  
Membered Ring ◽  
Boat Conformation ◽  
Twist Boat

scholarly journals (1β,2α,3α,7α,11α,13β)-1,3,7,11-Tetraacetoxy-2,13-bis(benzyloxy)-21-methyl-19,21-secohetisan-19-al hemihydrate

2009 ◽  
Vol 65 (6) ◽  
pp. o1432-o1432 ◽  
Author(s):  
Feng-Zheng Chen ◽  
Qing-Xiang Xiang ◽  
Yuan-Qin Zhang ◽  
Jun-Ru Xiong
Keyword(s):  
Crystal Structure ◽  
Organic Molecule ◽  
Chair Conformation ◽  
Heterocyclic Ring ◽  
Membered Ring ◽  
Boat Conformation ◽  
Solvent Water ◽  
Compound C ◽  
Benzene Rings ◽  
Carbocyclic Rings

In the crystal structure of the title compound, C43H46NO13·0.5H2O, the molecule assumes a U-shaped conformation, the terminal benzene rings being approximately parallel and partially overlapped with each other. The molecule contains eight alicyclic and heterocyclic rings. The cyclohexane rings adopt chair conformations, the other three six-membered carbocyclic rings form a bicyclo[2.2.2]octane system with a boat conformation for each six-membered ring, the six-membered heterocyclic ring has a chair conformation and both of the five-membered rings have envelope conformations. The solvent water molecule links with the organic moleculeviaclassic O—H...O and weak C—H...O hydrogen bonding in the crystal structure.

scholarly journals Crystal structure of 1-benzyl-4-(4-chlorophenyl)-2-imino-1,2,5,6,7,8,9,10-octahydrocycloocta[b]pyridine-3-carbonitrile

2014 ◽  
Vol 70 (10) ◽  
pp. 167-169 ◽  
Author(s):  
R. A. Nagalakshmi ◽  
J. Suresh ◽  
S. Maharani ◽  
R. Ranjith Kumar ◽  
P. L. Nilantha Lakshman
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Supramolecular Structure ◽  
Chair Conformation ◽  
Two Dimensional ◽  
Π Interactions ◽  
Compound C ◽  
Twist Boat

The title compound, C25H24ClN3, comprises a 2-iminopyridine ring fused with a cyclooctane ring, which adopts a twist boat–chair conformation. In the crystal, C—H...N interactions formR22(14) ring motifs and molecules are further connected by weak C—H...π interactions. The resulting supramolecular structure is a two-dimensional framework parallel to theabplane.

scholarly journals Crystal structure of hexamethyl 4,4′,4′′,4′′′,4′′′',4′′′''-[(1,3,5,2λ5,4λ5,6λ5-triazatriphosphinine-2,2,4,4,6,6-hexayl)hexakis(oxy)]hexabenzoate

2017 ◽  
Vol 73 (8) ◽  
pp. 1252-1254
Author(s):  
Jing Zhu ◽  
Guo Hui Hou ◽  
Qian Li ◽  
Fu Wei Zheng ◽  
Hong Liang Wei ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Crystal Packing ◽  
Van Der Waals Interactions ◽  
Dihedral Angles ◽  
Boat Conformation ◽  
Compound C ◽  
Benzene Rings ◽  
The Mean ◽  
Twist Boat

The title compound, C48H42N3O18P3, achieved in a two-step synthesis, comprises a cyclotriphosphazene core and six 4-methoxycarbonylphenoxy groups. Each P atom is attached to two substituents located up and down with respect to the plane of the phosphazene ring, the central P3N3 ring having a twist-boat conformation. The three O/P/O planes and five of the six benzene rings are nearly perpendicular to the mean plane through the phosphazene ring [dihedral angles = 82.98 (8)–88.92 (8)°], while the remaining benzene ring forms a dihedral angle of 25.72 (7)°. The crystal packing is stabilized by van der Waals interactions only.

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