3,10-Dihydroxydielmentha-5,11-Diene-4,9-Dione. A Diterpenoid (Bismonoterpenoid) With a Novel Carbon Skeleton

1986 ◽  
Vol 39 (11) ◽  
pp. 1843 ◽  
Author(s):  
RM Carman ◽  
LK Lambert ◽  
WT Robinson ◽  
n Vandonge
Keyword(s):  
High Field ◽  
Crystallographic Analysis ◽  
Diels Alder ◽  
Carbon Skeleton ◽  
Two Dimensional ◽  
X Ray

3,10-Dihydroxydielmentha-5,11-diene-4,9-dione, a diterpenoid (C20H28O4) from Callitris macleayana heartwood, is shown by degradation, by both one- and two-dimensional high-field n.m.r. exploration, and by X-ray crystallographic analysis to have a unique carbon skeleton formally based upon the Diels-Alder self- dimerization of a p- menthadienone.

scholarly journals Stepwise Synthesis, Hydrogen-Bonded Supramolecular Structure, and Magnetic Property of a Co–Mn Heterodinuclear Complex

2019 ◽  
Vol 5 (1) ◽  
pp. 5
Author(s):  
Ryoji Mitsuhashi ◽  
Takaaki Ueda ◽  
Masahiro Mikuriya
Keyword(s):  
Hydrogen Bond ◽  
Magnetic Property ◽  
Field Dependence ◽  
Crystallographic Analysis ◽  
Two Dimensional ◽  
Stepwise Synthesis ◽  
X Ray ◽  
Hydrogen Bond Interactions ◽  
Divalent State ◽  
Hydrogen Bond Networks

A cobalt(III)–manganese(II) heterometallic dinuclear complex, [MnII{CoIII(µ-Himn)3}Cl2(CH3OH)], was prepared by a metalloligand approach. X-ray crystallographic analysis indicated that the metalloligand [CoIII(Himn)3] underwent mer/fac geometrical isomerization upon coordination to a Mn ion. Owing to the non-coordinating N–H bonds in the [CoIII(Himn)3] moiety, the heterodinuclear complex exhibited hydrogen bond interactions with the Cl− ligand of the neighboring complex to construct two-dimensional hydrogen-bond networks. The bond distances around the Mn center and the χMT value at 300 K indicate that the Mn center is in a divalent state. The temperature dependence of the χMT product and field dependence of the magnetization showed the isotropic nature of the MnII center.

X-Ray Crystallographic Analysis of 2,5-Bis(diphenylmethylsilyl)thiophene Monooxide and the Diels-Alder Reaction of Thiophene Monooxide with Dienophiles

Heterocycles ◽  
1998 ◽  
Vol 47 (2) ◽  
pp. 793 ◽  
Author(s):  
Naomichi Furukawa ◽  
Shao-Zhong Zhang ◽  
Ernst Horn ◽  
Ohgi Takahashi ◽  
Soichi Sato ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Crystallographic Analysis ◽  
Diels Alder ◽  
X Ray ◽  
Diels Alder Reaction

Stereochemistry of α-Amino Oximes From the Monoterpene Hydrocarbons Car-3-ene, Limonene and α-Pinene

1992 ◽  
Vol 45 (6) ◽  
pp. 1077 ◽  
Author(s):  
AV Tkachev ◽  
AV Rukavishnikov ◽  
AM Chibiryaev ◽  
AY Denisov ◽  
YV Gatilov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanics ◽  
High Field ◽  
Crystallographic Analysis ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Molecular Mechanics Calculations ◽  
Space Group ◽  
X Ray ◽  
Monoterpene Hydrocarbons

The conformation and configuration of the α-amino oximes derived from the terpene hydrocarbons car-3-ene, limonene and α- pinene have been determined by n.m.r. spectroscopy (high-field 1H n.m.r., 13C n.m.r., INADEQUATE technique), molecular mechanics calculations and X-ray crystallographic analysis. The crystal structure of (lS,3S,6R)-3-dimethylamino-caran-4-one (E)-oxime has been determined by X-ray diffraction; crystals are orthorhombic, space group P 212121 with a 11.421(2), b 13.223(2), c 16.992(4) �, Z 8. Refinement on 1730 observed reflections measured with Cu K α radiation converged at R 0.053.

The synthesis and reactivity of α-oxosulfines

1989 ◽  
Vol 67 (3) ◽  
pp. 369-381 ◽  
Author(s):  
Ian W. J. Still ◽  
Donald V. Frazer ◽  
Donna K. T. Hutchinson ◽  
Jeffery F. Sawyer
Keyword(s):  
Crystal Structures ◽  
Reaction Pathway ◽  
Reactive Intermediates ◽  
Crystallographic Analysis ◽  
Diels Alder ◽  
Electrophilic Addition ◽  
X Ray ◽  
Major Reaction ◽  
Sulfenic Acids

Thiochroman-4-one and cyclohexanone have been converted into the corresponding α-oxosulfines and the behaviour of these reactive intermediates with a range of alkenes and alkynes has been examined. In contrast to some earlier work, the major reaction pathway does not involve formation of the initially expected Diels–Alder adducts but instead a series of adducts involving electrophilic addition to the alkene or alkyne, with concomitant deoxygenation and incorporation of chlorine. The structures of these adducts have been determined by the usual spectroscopic means and, in two representative cases, by X-ray crystallographic analysis. The crystal structures, which include unusual features such as relatively short S … O nonbonding contacts, are discussed in detail. Keywords: (α-oxo)sulfines, sulfenic acids, X-ray analysis, electrophilic addition.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Tubulin structure at intermediate resolution

1995 ◽  
Vol 53 ◽  
pp. 852-853
Author(s):  
K. H. Downing ◽  
S. G. Wolf ◽  
E. Nogales
Keyword(s):  
High Resolution ◽  
Structural Data ◽  
Therapeutic Drug ◽  
Zinc Ions ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Negative Stain ◽  
Functional Mechanisms ◽  
Tubulin Structure

Microtubules are involved in a host of critical cell activities, many of which involve transport of organelles through the cell. Different sets of microtubules appear to form during the cell cycle for different functions. Knowledge of the structure of tubulin will be necessary in order to understand the various functional mechanisms of microtubule assemble, disassembly, and interaction with other molecules, but tubulin has so far resisted crystallization for x-ray diffraction studies. Fortuitously, in the presence of zinc ions, tubulin also forms two-dimensional, crystalline sheets that are ideally suited for study by electron microscopy. We have refined procedures for forming the sheets and preparing them for EM, and have been able to obtain high-resolution structural data that sheds light on the formation and stabilization of microtubules, and even the interaction with a therapeutic drug.Tubulin sheets had been extensively studied in negative stain, demonstrating that the same protofilament structure was formed in the sheets and microtubules. For high resolution studies, we have found that the sheets embedded in either glucose or tannin diffract to around 3 Å.

Two dimensional Sr silicate grown on Si(001) studied using X-ray Photoelectron Spectroscopy

2006 ◽  
Vol 132 ◽  
pp. 87-90
Author(s):  
M. El Kazzi ◽  
G. Delhaye ◽  
S. Gaillard ◽  
E. Bergignat ◽  
G. Hollinger
Keyword(s):  
Photoelectron Spectroscopy ◽  
Two Dimensional ◽  
X Ray
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