Pigments of Fungi. Part 70.* Total Synthesis of (R)-Semixanthomegnin and the X-Ray Crystal Structure of (±)-7-Chloro-10-methoxy-3-methyl-3, 4-dihydro-1 H-naphtho[2,3-c]pyran-1,6,9-trione

2003 ◽  
Vol 56 (1) ◽  
pp. 49 ◽  
Author(s):  
Ann S. Cotterill ◽  
Christopher D. Donner ◽  
Melvyn Gill ◽  
Jonathan M. White
Keyword(s):  
Crystal Structure ◽  
Total Synthesis ◽  
Single Crystal ◽  
Structure Analysis ◽  
Propylene Oxide ◽  
Cycloaddition Reaction ◽  
X Ray

(R)-Semixanthomegnin (8), which has been converted by others to the mould metabolite (3R,3′ R)-xanthomegnin (9), is prepared in seven steps from (R)-propylene oxide (16). A single-crystal X-ray structure analysis of (±)-7-chloro-10-methoxy-3-methyl-3,4-dihydro-1H-naphtho[2,3-c]pyran-1,6,9-trione (25) confirms the regiochemistry of the cycloaddition reaction between 2,5-dichloro-1,4-benzoquinone and the new, highly oxygenated, chiral butadiene derivative (2).

Stereoselective Syntheses of Alkyl Z-2-(2-amino-4-oxo-1,3-selenazol- 5(4H)-ylidene)acetates in Solvent-Free Conditions, X-Ray Single Crystal Structure Analysis of Ethyl Z-2-(2-amino-4-oxo-1,3-selenazol- 5(4H)-ylidene)acetate

2005 ◽  
Vol 60 (5) ◽  
pp. 569-571 ◽  
Author(s):  
Ali Ramazani ◽  
Ali Morsali ◽  
Bijan Ganjeie ◽  
Ali Reza Kazemizadeh ◽  
Ebrahim Ahmadi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Solvent Free ◽  
Single Crystal Structure ◽  
X Ray ◽  
Solvent Free Conditions ◽  
Stereoselective Syntheses ◽  
Single Crystal Structure Analysis

Selenourea reacts with dialkyl acetylenedicarboxylates under solvent-free conditions to form 1:1 adducts, which undergo a cyclization reaction to produce alkyl Z-2-(2-amino-4-oxo-1,3-selenazol- 5(4H)-ylidene)acetates, in good yields. The stereochemistry of the ethyl Z-2-(2-amino-4-oxo-1,3- selenazol-5(4H)-ylidene)acetate was established by X-ray single crystal structure analysis. The reaction is completely stereoselective.

scholarly journals Preparation and Crystal Structure of Zinc Bis[orotate(1–)] Octahydrate

1993 ◽  
Vol 48 (7) ◽  
pp. 961-964 ◽  
Author(s):  
Otto Kumberger ◽  
Jürgen Riede ◽  
Hubert Schmidbaur
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Medical Treatment ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Structure Analysis ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray

A discrete zinc bis[orotate(1—)] complex of the composition Zn(OrH)2·8 H2O has been isolated and characterized by a single-crystal X-ray structure analysis. The crystals are monoclinic, space group P21/c (No. 14), Z = 2, a = 10.884(2), b = 12.896(1), c = 6.954(1) Å, β = 98.27(1)°. The crystal lattice features hexaquo complexes of zinc, the Zn(H2O)62+ cations being associated with two hydrated OrH- ions only through hydrogen bonds. The results are relevant for applications of zinc orotates in medical treatment.

X-ray and neutron diffraction investigation at 298 K of NH4I · NH3 and ND4I · ND3 containing the cation H3N – H … NH3+ and D3N – D … ND3+

1992 ◽  
Vol 200 (3-4) ◽  
Author(s):  
H. J. Berthold ◽  
E. Vonholdt ◽  
R. Wartchow ◽  
T. Vogt
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Single Crystal Structure ◽  
X Ray ◽  
Single Crystal Structure Analysis

AbstractNHA single crystal structure analysis of NThe deuterated compound NThe structures of the ordered low temperature phases will be reported separately.

scholarly journals Crystal Structure and Dielectric Property of Endohedral Lithium Fullerene

2014 ◽  
Vol 70 (a1) ◽  
pp. C195-C195
Author(s):  
Shinobu Aoyagi ◽  
Kunihisa Sugimoto ◽  
Hiroshi Okada ◽  
Norihisa Hoshino ◽  
Tomoyuki Akutagawa
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Dielectric Property ◽  
Low Temperature ◽  
Dielectric Permittivity ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Structure Analysis ◽  
X Ray ◽  
Dielectric Phase

Endohedral lithium fullerene Li+@C60 can have a dielectric polarization by the off-centered location of the Li+ cation inside the C60 cage. The x-ray structure analysis of the PF6– salt [Li@C60](PF6) revealed that the Li+ cation occupies two off-centered equivalent positions at 20 K and hence the crystal is non-polar [1]. The disordered structure at low temperature is explained by a static orientation disorder of polar Li+@C60 cations and/or a dynamic tunneling of the Li+ cation inside the C60 cage. The Li+ tunneling would be suppressed by an intermolecular interaction at lower temperature and a dielectric phase transition might be induced. We reveal the dielectric property and crystal structure of [Li@C60](PF6) below 20 K in this study. The temperature dependence of the dielectric permittivity was measured for the single crystal down to 9 K. The dielectric permittivity increases with decreasing temperature according to the Curie-Weiss law. Such a behavior was also observed in H2O@C60 crystal but not in empty C60 crystal [2]. No dielectric phase transition was observed in H2O@C60 down to 8 K. In contrast, a dielectric anomaly suggesting a phase transition was observed in [Li@C60](PF6) around 18 K. The single-crystal x-ray diffraction experiment below 20 K was also performed at SPring-8 BL02B1. The crystal has a cubic structure at 20 K [1]. The temperature dependence of the cubic lattice constant shows no anomaly around 18 K. However, diffraction peaks that are forbidden for the given structure appear below 18 K. Thus the crystal symmetry is lowered by the dielectric phase transition. We present the result of the crystal structure analysis of the newly discovered low-temperature phase.

Stereoselective Synthesis of Multifunctionalized Nitrones via Conjugate Addition Between α-Halogeno Hydrazones and Nitroso Compounds

Synlett ◽  
2021 ◽  
Author(s):  
Hong-Wu Zhao ◽  
Xiao-Fan Bi ◽  
Hai-Liang Pang ◽  
Zhe Tang ◽  
Heng Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Analysis ◽  
Chemical Structure ◽  
Stereoselective Synthesis ◽  
Conjugate Addition ◽  
Crystal Structure Analysis ◽  
Nitroso Compounds ◽  
X Ray ◽  
Single Crystal Structure Analysis

In the presence of Na2CO3, the conjugate addition between α-halogeno hydrazones and nitroso compounds proceeded readily, thus delivering multifunctionalized nitrones in the reasonable chemical yields with excellent strereoselectivities. The chemical structure and stereochemical configuration of title chemical entities were unambiguously identified by an X-ray single crystal structure analysis.

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