An unusual twist-boat conformation for a six-membered ring phosphorus heterocycle

1979 ◽  
Vol 101 (17) ◽  
pp. 4925-4928 ◽  
Author(s):  
David G. Gorenstein ◽  
Robert Rowell
Keyword(s):  
Membered Ring ◽  
Boat Conformation ◽  
Twist Boat

scholarly journals (1S,2R,3S,6S,7R)-3,7,11,11-Tetramethyl-6,7-epoxybicyclo[5.4.0]undecane-2-ol

2014 ◽  
Vol 70 (5) ◽  
pp. o595-o595
Author(s):  
Mohamed Loubidi ◽  
Ahmed Benharref ◽  
Lahcen El Ammari ◽  
Mohamed Saadi ◽  
Moha Berraho
Keyword(s):  
Hydrogen Bonds ◽  
Title Compound ◽  
Membered Ring ◽  
Boat Conformation ◽  
Axis Direction ◽  
Cedrus Atlantica ◽  
Compound C ◽  
Twist Boat

The title compound, C15H26O2, was synthesized from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the Atlas cedar (cedrus atlantica). The molecule is built up from a seven-membered ring to which a six- and a three-membered ring are fused. The seven- and six-membered rings each have a twist-boat conformation. In the crystal, O—H...O hydrogen bonds link the molecules into zigzag chains running along theb-axis direction.

Synthesis and Structure of the Helicate (M)-(–)-[Pt2 {(R,R)-tetraphos}2](CF3SO3)4 · 4.5 H2O

2004 ◽  
Vol 59 (11-12) ◽  
pp. 1458-1461
Author(s):  
Heather J. Kitto ◽  
A. David Rae ◽  
Anthony C. Willis ◽  
Johann Zank ◽  
S. Bruce Wild
Keyword(s):  
Membered Ring ◽  
Boat Conformation ◽  
Fold Axis ◽  
Space Group ◽  
Independent Molecules ◽  
Α Helix ◽  
Twist Boat

The complex (M)-(-)-[Pt2{(R,R)-tetraphos}2](CF3SO3)4 · 4.5 H2O, where tetraphos = 1,1,4,7, 10,10-hexaphenyl-1,4,7,10-tetraphosphadecane, has been isolated and structurally characterized. The compound crystallizes in the space group C2 with two crystallographically different, but very similar, cations in the structure, each of which contains a 2-fold axis coincident with the crystallographic 2-fold axis. Each independent cation of the salt consists of a double-stranded, diplatinum(II) helicate that completes a ca. one-eighth turn of a double α-helix in the M direction, as evidenced by the angle between the two, non-orthogonal PtP4 square planes in each of the independent molecules. A feature of the structures is the 10-membered ring containing the two platinum atoms and the four chiral phosphorus stereocentres of R configuration; this ring has a distorted twist-boat-chair-boat conformation of λ helicity, which is responsible for the M twist of the helicate.

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 Crystal structure of (1S,3R,8R,9R,10S)-2,4,6-tris(2,2-dichloro-3,7,7,10-tetramethyltricyclo[6.4.0.01,3]dodec-9-yl)cyclotriboroxane

2015 ◽  
Vol 71 (8) ◽  
pp. 941-943
Author(s):  
Ahmed Benharref ◽  
Lahcen El Ammari ◽  
Mohamed Saadi ◽  
Noureddine Mazoir ◽  
Moha Berraho
Keyword(s):  
Crystal Packing ◽  
Membered Ring ◽  
Van Der Waals Interactions ◽  
Maximum Deviation ◽  
Boat Conformation ◽  
Ring Systems ◽  
Compound C ◽  
Fused Ring ◽  
The Mean ◽  
Twist Boat

The title compound, C48H75B3Cl6O3, was synthesized in two steps from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The molecule consists of an almost planar cyclotriboroxane ring [maximum deviation = 0.036 (2) Å] linked to three identical fused ring systems with different conformations. Each of the three attached ring systems is built up from a seven-membered ring to which a six- and a three-membered ring are fused. The three six-membered rings have a twist-boat conformation, whereas the seven-membered rings display boat, chair and twist-boat conformations. The dihedral angles between the central boroxane ring and the mean planes of the attached six-membered rings are 63.67 (18), 54.89 (2) and 56.57 (19)°. The crystal packing is governed only by van der Waals interactions.

Synthesis of Methyl-5,6,11,12-tetrahydrodibenzo[a,e]cyclooctenols and a conformational study by proton nuclear magnetic resonance

1983 ◽  
Vol 36 (3) ◽  
pp. 517 ◽  
Author(s):  
KE White ◽  
BJ Slater ◽  
SH Graham
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Membered Ring ◽  
Proton Nuclear Magnetic Resonance ◽  
Boat Conformation ◽  
Geminal Proton ◽  
Twist Boat ◽  
Axial Site ◽  
Nuclear Magnetic

A series of methyl-5,6,11,12-tetrahydrodibenzo[a,e]cycloocten-5-ols were synthesized, and their conformations assigned by means of proton nuclear magnetic resonance. Placing substituents in three of the four available sites on the eight-membered ring enabled the chemical shifts of the geminal proton to be observed. It was found that the three sites have intrinsic chemical shifts. The compounds studied were found to populate a twist-boat conformation, with bulky substituents preferentially populating the axial site.

scholarly journals Ethyl 2,6-bis(4-chlorophenyl)-1-isocyano-4-oxocyclohexanecarboxylate

2014 ◽  
Vol 70 (7) ◽  
pp. o802-o802
Author(s):  
Dawei Zhang ◽  
Peng Yang ◽  
Wei Liu ◽  
Jing Li
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Membered Ring ◽  
Boat Conformation ◽  
Equatorial Position ◽  
Aryl Group ◽  
Compound C ◽  
Twist Boat

In the title compound, C22H19Cl2NO3, the central six-membered ring is in a twist-boat conformation. The two aryl groups are in equatorial positions,transto each other and with a dihedral angle of 77.50 (2)° between them. One of the least hindered –CH2– groups and one of the aryl-substituted C atoms, with its axial H atom, are in the flagpole positions. The ethoxycarbonyl group is in an equatorial position and iscisto the second aryl group. In the crystal, molecules are linkedviaweak C—H...O hydrogen bonds, forming chains along [010].

2,2,7,7-Tetraphenyl-2,7-dihydrodibenz[c,e]oxepine

2006 ◽  
Vol 62 (4) ◽  
pp. o1478-o1479 ◽  
Author(s):  
Winai Ieawsuwan ◽  
Miriam Bru Roig ◽  
Michael Bolte
Keyword(s):  
Title Compound ◽  
Membered Ring ◽  
Boat Conformation ◽  
Intensity Data ◽  
Compound C ◽  
Twist Boat

The structure of the title compound, C38H28O, has previously been reported by Hirano, Toyota & Toda [Heterocycles (2004), 62, 749–756]. Since these authors did not publish any coordinates, we present here a redetermination of this structure using new intensity data. The molecule has chemical but not crystallographic C 2 symmetry. The central seven-membered ring adopts a twist-boat conformation.

Synthesis and conformations of α-aminoadipyl- and glycyl-α-aminoadipylthiazepine sulfoxides

1981 ◽  
Vol 59 (2) ◽  
pp. 406-421 ◽  
Author(s):  
Saul Wolfe ◽  
Raymond John Bowers ◽  
Syed Khaqan Hasan ◽  
Peter Michael Kazmaier
Keyword(s):  
Hydrogen Bond ◽  
Carbon Atom ◽  
Formic Acid ◽  
Chair Conformation ◽  
Membered Ring ◽  
Amide Proton ◽  
Penicillin Biosynthesis ◽  
Boat Conformation ◽  
Internal Hydrogen Bond ◽  
Twist Boat

The title compounds, having the R-absolute configurations at sulfur, and labelled with 14C at carbons 5, 6, and 7 of the seven-membered ring, have been synthesized by condensation of isotopically labelled 3D-benzhydryloxycarbonyl-6L-amino-2,2-dimethyl-5-oxoperhydro-1,4-thiazepine with N-Boc- and α-benzhydryl-protected L-α-aminoadipic acid and glycyl-L-α-aminoadipic acid, followed by oxidation with m-chloroperoxybenzoic acid and complete deprotection with formic acid. The conformations of the sulfoxides, and related thiazepines and thiazepine sulfoxides, have been examined by 1Hmr spectroscopy. All thiazepines, and the two title sulfoxides, appear to exist in a twist boat conformation. Most other sulfoxides exist in a chair conformation, which is stabilized by an internal hydrogen bond between the sulfinyl oxygen and the amide proton at C6; when this hydrogen bond is not present, both chair and twist boat conformations may be observable. The title compounds are of interest as possible intermediates in penicillin biosynthesis from glycyl-δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine (GACV) or ACV, according to a new theory, which deals, in particular, with the stereochemical course of the biosynthesis at the beta (β) carbon atom of valine.

scholarly journals Crystal structure of (1S,3R,8R,9S,10R)-10-bromomethyl-2,2-dichloro-9,10-epoxy-3,7,7-trimethyltricyclo[6.4.0.01,3]dodecane

2015 ◽  
Vol 71 (5) ◽  
pp. o284-o285 ◽  
Author(s):  
Ahmed Benharref ◽  
Lahcen El Ammari ◽  
Mohamed Saadi ◽  
Moha Berraho
Keyword(s):  
Crystal Structure ◽  
Essential Oil ◽  
Title Compound ◽  
Membered Ring ◽  
Anomalous Dispersion ◽  
Boat Conformation ◽  
Compound C ◽  
Dispersion Effects ◽  
Absolute Structure ◽  
Twist Boat

The title compound, C16H23BrCl2O, was synthesized in three steps from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (cedrus atlantica). The molecule is built up from two fused six- and seven-membered rings, each linked to a three-membered ring. The six-membered ring has a screw-boat conformation, whereas the seven-membered ring displays a twist-boat conformation. The absolute structure was established unambiguously from anomalous dispersion effects.

Sign in / Sign up

Export Citation Format

Share Document