Constitution and absolute stereochemistry of the biphenyl alkaloid lythranine: X-ray analysis of the crystal structure of bromolythranine hydrobromide ethanol solvate

1972 ◽  
pp. 2073 ◽  
Author(s):  
R. J. McClure ◽  
G. A. Sim
Keyword(s):  
Crystal Structure ◽  
X Ray ◽  
Ethanol Solvate ◽  
Absolute Stereochemistry

Absolute stereochemistry of disidein and of two new related halogenated sesterterpenoids. Two-dimensional nmr studies and x-ray crystal structure

Tetrahedron ◽  
1987 ◽  
Vol 43 (20) ◽  
pp. 4777-4784 ◽  
Author(s):  
G. Cimino ◽  
S. De Rosa ◽  
S. De Stefano ◽  
R. Puliti ◽  
G. Strazzullo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Two Dimensional ◽  
Nmr Studies ◽  
X Ray ◽  
Absolute Stereochemistry

The Constituents of Marine Sponges. VII. The Absolute Stereochemistry of Aplyroseol-1.

1997 ◽  
Vol 50 (4) ◽  
pp. 391 ◽  
Author(s):  
Trevor W. Hambley ◽  
Walter C. Taylor ◽  
Stephen Toth
Keyword(s):  
Crystal Structure ◽  
Marine Sponges ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of aplyroseol-1 (1), a diterpenoid isolated from Aplysillarosea Barrois, has been established as (5S; 7R; 8S; 9R; 10S; 13R; 14R; 15R) by determining the crystal structure of the p-bromobenzoyl derivative (3) by X-ray diffraction methods. The structure was refined to a residual of 0·032 for 1451 independent observed reflections. The crystals are monoclinic, space group P 21, a 6·668(8), b 20·04(1), c 10·974(3) Å, β 98·04(7)°.

Crystal Structure of Tris(1,10-phenanthroline)mercury(II) Trifluoromethanesulfonate

1979 ◽  
Vol 32 (10) ◽  
pp. 2195 ◽  
Author(s):  
GB Deacon ◽  
CL Raston ◽  
D Tunaley ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Title Compound ◽  
Unit Cell Volume ◽  
Octahedral Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ethanol Solvate ◽  
The Mean ◽  
Trigonal Prismatic

The crystal structure of the ethanol solvate of the title compound, [Hg(phen)3](CF3S03)2 (phen =1,10-phenanthroline), has been determined at 295(1) K by single-crystal X-ray diffraction and refined by least squares to a residual of 0�043 for 2939 'observed' reflections. Crystals are monoclinic: C2/c, a 25�25(1), b 10�960(4), c 18�949(6) �, β 129�32(2)�, Z 4. The cation is centred on a crystallographictwofold axis and has approximate D3 point symmetry. The deviation of the mercury(II) environment from octahedral symmetry toward the trigonal-prismatic limit is considerable, the mean trans N-Hg-N angle being 154�52�. <Hg-N> is 2�400 �. The unit cell volume is considerablydependent on crystallization solvent, being larger for the ethanol solvate than for solvent-free crystals obtained from aqueous solution.

Main group (IIIA or 13) complexes of benzohydroxamic acid and the crystal structure of tris(benzohydroxamato)indium(III)

1988 ◽  
Vol 66 (8) ◽  
pp. 1809-1813 ◽  
Author(s):  
Carey A. Matsuba ◽  
Steven J. Rettig ◽  
Chris Orvig
Keyword(s):  
Crystal Structure ◽  
High Yield ◽  
Acetohydroxamic Acid ◽  
X Ray Diffraction ◽  
Fourier Methods ◽  
Full Matrix ◽  
X Ray ◽  
Benzohydroxamic Acid ◽  
Ethanol Solvate ◽  
Indium Complex

A series of tris(benzohydroxamato)metal(III) complexes has been prepared and characterized wherein the metals are aluminum, gallium, and indium. The complexes are synthesized in high yield from aqueous solution. The indium complex, as its ethanol solvate In(C7H6NO2)3•C2H5OH, has been studied by single crystal X-ray diffraction. The crystals are monoclinic with a = 11.091(2), b = 18.065(3), c = 12.861(2) Å, β = 105.55(1)°, Z = 4, and space group P21/n. The structure was solved by Patterson and Fourier methods and was refined by full-matrix least-squares procedures to R = 0.038 and Rw = 0.037 for 2579 reflections with I ≥ 3σ(I). Bond lengths and angles in the compound were normal, although there is a strong In—O(C) interaction; the arrangement of the three ligands is mer. There is extensive hydrogen bonding involving all possible donors. All three complexes have been studied by mass spectrometry, and by infrared and nuclear magnetic resonance (1H, 27Al) spectroscopies. Parallel studies have been attempted with acetohydroxamic acid.

Photodecarbonylation of chiral cyclobutanones

1997 ◽  
Vol 75 (5) ◽  
pp. 518-522 ◽  
Author(s):  
Jailall Ramnauth ◽  
Edward Lee-Ruff
Keyword(s):  
Crystal Structure ◽  
Triplet State ◽  
Structure Determination ◽  
Major Product ◽  
X Ray ◽  
Principal Product ◽  
Independent Synthesis ◽  
Optically Pure ◽  
Absolute Stereochemistry

Triplet photosensitized irradiation of 2(S),3(R)-bis[(benzoyloxy)methyl]cyclobutanone gave optically pure (−)E-1(S),2(S)-bis(benzoyloxymethyl)cyclopropane as a major product in the nonpolar fraction along with its stereoisomer and cycloelimination products. The absolute stereochemistry of the chiral cyclopropane was established by independent synthesis and X-ray crystal structure determination of a synthetic precursor. The distribution of decarbonylation and cycloelimination products was inversely dependent on the concentration of the substrate. Irradiation of the same ketone in tetrahydrofuran or benzene gave mostly cycloelimination products. Addition of Michler's ketone increased the ratio of photodecarbonylation, suggesting a triplet state pathway for this process. This was corroborated by the addition of dicyanoethylene, which showed significant quenching of photodecarbonylation. Irradiation of 2(S)-[(benzoyloxy)methyl]cyclobutane in acetone gave the corresponding cyclopropane as the principal product. Keywords: photodecarbonylation, chiral cyclopropanes, cyclobutanones, triplet sensitization.

scholarly journals Novel Ansa-Chain Conformation of a Semi-Synthetic Rifamycin Prepared Employing the Alder-Ene Reaction: Crystal Structure and Absolute Stereochemistry

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 734-743
Author(s):  
Christopher S. Frampton ◽  
James H. Gall ◽  
David D. MacNicol
Keyword(s):  
Crystal Structure ◽  
Rna Synthesis ◽  
Crystal Structure Analysis ◽  
Orthorhombic Space Group ◽  
Ene Reaction ◽  
X Ray ◽  
Diethyl Azodicarboxylate ◽  
Hydroxy Groups ◽  
Absolute Stereochemistry ◽  
Predominant Product

Rifamycins are an extremely important class of antibacterial agents whose action results from the inhibition of DNA-dependent RNA synthesis. A special arrangement of unsubstituted hydroxy groups at C21 and C23, with oxygen atoms at C1 and C8 is essential for activity. Moreover, it is known that the antibacterial action of rifamycin is lost if either of the two former hydroxy groups undergo substitution and are no longer free to act in enzyme inhibition. In the present work, we describe the successful use of an Alder-Ene reaction between Rifamycin O, 1 and diethyl azodicarboxylate, yielding 2, which was a targeted introduction of a relatively bulky group close to C21 to protect its hydroxy group. Many related azo diesters were found to react analogously, giving one predominant product in each case. To determine unambiguously the stereochemistry of the Alder-Ene addition process, a crystalline zwitterionic derivative 3 of the diethyl azodicarboxylate adduct 2 was prepared by reductive amination at its spirocyclic centre C4. The adduct, as a mono chloroform solvate, crystallized in the non-centrosymmetric Sohnke orthorhombic space group, P212121. The unique conformation and absolute stereochemistry of 3 revealed through X-ray crystal structure analysis is described.

Complexes of structural analogues of terpyridyl with iron and zinc; the x-ray crystal structure of bis[2,6-bis(benzimidazol2-yl)pyridine]iron(II) trifluoromethylsulphonate bis-ethanol solvate

Polyhedron ◽  
1992 ◽  
Vol 11 (6) ◽  
pp. 635-646 ◽  
Author(s):  
Stephane Rüttimann ◽  
Catherine M. Moreau ◽  
Alan F. Williams ◽  
Gerald Bernardinelli ◽  
Anthony W. Addison
Keyword(s):  
Crystal Structure ◽  
X Ray ◽  
Ethanol Solvate ◽  
Structural Analogues ◽  
Iron And Zinc

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

X-ray Crystal Structure of ?9-THC-tosylate

Planta Medica ◽  
2008 ◽  
Vol 74 (03) ◽  
Author(s):  
W Gul ◽  
P Carvalho ◽  
D Slade ◽  
M Avery ◽  
JR Duchek ◽  
...  
Keyword(s):  
Crystal Structure ◽  
X Ray

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

Sign in / Sign up

Export Citation Format

Share Document