Studies Directed Towards the Total Synthesis of Anticapsin. X-Ray Crystal-Structure of (1RS,2SR,4RS,5RS,6SR)-5-Hydroxy-2-phthalimido-1-trimethylsilyloxy-bicyclo[2.2.2]octane-2,6-carbolactone

1990 ◽  
Vol 43 (11) ◽  
pp. 1827 ◽  
Author(s):  
MJ Crossley ◽  
TW Hambley ◽  
AW Stamford
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Total Synthesis ◽  
Synthetic Approach ◽  
Hydrogen Atoms ◽  
Full Matrix ◽  
X Ray ◽  
X Ray Crystallography ◽  
Relative Stereochemistry ◽  
Atomic Parameters

The relative stereochemistry of methyl 2-phthalimido-1- trimethylsilyloxybicyclo[2.2.2]oct-5-ene-2-carboxylate (9) and its 5,6-epoxide (10), intermediates in a synthetic approach to the amino acid antibiotic anticapsin, were established by the TiCl4-mediated cyclization of (10) to the carbolactone (12); the structure of which was proved by single-crystal X-ray crystallography. Full-matrix least- squares refinement of all atomic parameters with individual isotropic thermal parameters for the hydrogen atoms by using 1446 reflections converged at R 0.036. Crystals of (12) are monoclinic, P21/c, a 12.342(3), b 12.239(2), c 13.405(3) Ǻ, β 99.34(2)°, Z 4.

An X-Ray Study of the Synthetic Intermediate 9-Cyano-1,10-Dimethyl-6-Ethylenedioxy-1-Octalin

1975 ◽  
Vol 53 (2) ◽  
pp. 192-194 ◽  
Author(s):  
Harry Lynton ◽  
Pik-Yuen Siew
Keyword(s):  
Crystal Structure ◽  
Total Synthesis ◽  
Direct Methods ◽  
Hydrogen Atoms ◽  
Full Matrix ◽  
X Ray ◽  
Ring Junction ◽  
Cell Dimensions ◽  
R Value ◽  
Synthetic Intermediate

The crystal structure of the synthetic intermediate, 9-cyano-1,10-dimethyl-6-ethy]enedioxy-1-octalin, C15H21O2N, was solved by direct methods. The compound crystallizes in the space group p21/c with cell dimensions a = 12.282(4), b = 7.144(3), c = 15.619(5) Å, β = 104.04(1)°. Refinement was carried out isotropically for hydrogen and anisotropically for non-hydrogen atoms using full matrix least squares to an R-value of 0.043 for 1669 observed reflections.This compound, which has a cis configuration at the octalin ring junction, is a precursor to a moiety of the alkaloid thelepogine. The cis conformation is essential for total synthesis of thelopogine by this route.

Structure, Stereochemistry and Novel 'Hydrogen Bonding' in Two Bipyridinium Salts of the B10H102- Anion

1987 ◽  
Vol 40 (12) ◽  
pp. 2097 ◽  
Author(s):  
DJ Fuller ◽  
DL Kepert ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Charge Transfer ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
Full Matrix ◽  
X Ray ◽  
Structure Determinations ◽  
Positively Charged

Crystal structure determinations of (LH)2(B10H10), (1), and (LH2)(B10H10), (2), L = 2,2'- bipyridine , have been carried out by single-crystal X-ray diffraction methods at 295 K, being refined by full-matrix least squares to residuals of 0.041, 0.047 for 1758, 1771 'observed' independent reflections respectively. Crystals of (1) are monoclinic, P21/n, a 12.040(7), b 17.71(1), c 11.142(4) �, β 101.78(4)�, Z 4. Crystals of (2) are monoclinic, P21/c, a 9.937(4), b 10.837(3), c 14.856(5) �, β 109 2l(3)�, Z 4. The colour of the compounds is accounted for by charge-transfer interactions of a novel type, namely between the positively charged cationic acid hydrogen atoms and the negatively charged non-apical hydrogen atoms of the anion. In yellow (1), these distances are 2.26(5) �, while in red (2), they are much shorter, being 1.89(4), 1.97(3) �.

scholarly journals New developments in crystallography: exploring its technology, methods and scope in the molecular biosciences

2017 ◽  
Vol 37 (4) ◽  
Author(s):  
John R. Helliwell
Keyword(s):  
Crystal Structure ◽  
Data Bank ◽  
Crystal Structure Analysis ◽  
Public Understanding ◽  
Biological Macromolecules ◽  
Hydrogen Atoms ◽  
X Ray ◽  
The Public ◽  
X Ray Crystallography ◽  
Chemical Catalysis

Since the Protein Data Bank (PDB) was founded in 1971, there are now over 120,000 depositions, the majority of which are from X-ray crystallography and 90% of those made use of synchrotron beamlines. At the Cambridge Structure Database (CSD), founded in 1965, there are more than 800,000 ‘small molecule’ crystal structure depositions and a very large number of those are relevant in the biosciences as ligands or cofactors. The technology for crystal structure analysis is still developing rapidly both at synchrotrons and in home labs. Determination of the details of the hydrogen atoms in biological macromolecules is well served using neutrons as probe. Large multi-macromolecular complexes cause major challenges to crystallization; electrons as probes offer unique advantages here. Methods developments naturally accompany technology change, mainly incremental but some, such as the tuneability, intensity and collimation of synchrotron radiation, have effected radical changes in capability of biological crystallography. In the past few years, the X-ray laser has taken X-ray crystallography measurement times into the femtosecond range. In terms of applications many new discoveries have been made in the molecular biosciences. The scope of crystallographic techniques is indeed very wide. As examples, new insights into chemical catalysis of enzymes and relating ligand bound structures to thermodynamics have been gained but predictive power is seen as not yet achieved. Metal complexes are also an emerging theme for biomedicine applications. Our studies of coloration of live and cooked lobsters proved to be an unexpected favourite with the public and schoolchildren. More generally, public understanding of the biosciences and crystallography’s role within the field have been greatly enhanced by the United Nations International Year of Crystallography coordinated by the International Union of Crystallography. This topical review describes each of these areas along with illustrative results to document the scope of each methodology.

Preparation and X-ray crystal structure of (4bα,6β,9β,9aα,10α,13α)-4b,5,6,7,8,9,9a,10,11,12,13,14-dodecahydro-4b-phenyl-6,9:10,13-dimethanodicyclohepta[a,c]naphthalene

1980 ◽  
Vol 58 (17) ◽  
pp. 1847-1850 ◽  
Author(s):  
Alan Richard Harris ◽  
Keith Mills ◽  
Michael Martin-Smith ◽  
Peter Murray-Rust ◽  
Judith Murray-Rust
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
The Novel ◽  
Oxidative Dimerization ◽  
Full Matrix ◽  
X Ray ◽  
X Ray Crystallography

The novel hexacyclic title hydrocarbon, formed by an unusual oxidative dimerization of 3-phenylbicyclo[3,2,1]oct-2-ene, has been isolated and its structure elucidated by means of X-ray crystallography. The trivial name 4b-phenylmariontetraene is proposed for the hydrocarbon. Crystals are orthorhombic, Pbca; a = 21.87(2), b = 10.57(2), c = 17.41(2) Å from diffractometer measurements (Mo [Formula: see text] radiation). V = 4024.2 Å3, Z = 8, Dc = 1.21 Mg m−3, F(000) = 1584, μ = 0.34 cm−3. The structure was solved by direct phasing methods with MULTAN 78 and was refined by weighted full-matrix least-squares procedures to R = 0.046 for 2287 observed reflexions.

Crystal structure of Bis(O-ethylxanthato)-1,10-phenanthrolinecadmium(II)

1976 ◽  
Vol 29 (4) ◽  
pp. 739 ◽  
Author(s):  
CL Raston ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Title Compound ◽  
Crystallographic Axis ◽  
Full Matrix ◽  
X Ray ◽  
X Ray Crystallography ◽  
Phenanthroline Ligand

The crystal structure of the title compound, [Cd(C12H8N2)(CS2OEt)2], has been determined by X-ray crystallography using diffractometer data at 295 K and refined by full matrix least squares to a residual of 0.06 for 1350 'observed' reflections. Crystals are orthorhombic, P bcn, a = 14.870(4), b = 14.549(8), c = 10.249(1) �, Z = 4. The molecule lies on a twofold crystallographic axis; the phenanthroline ligand is symmetrically bidentate [Cd-N, 2.386(8) �], while the ethylxanthateligand is somewhat asymmetric [Cd-S, 2.647(3), 2.727(3)4 with a correspondingly asymmetric C-S geometry [C-S, 1.72(1), 1.66(1) �].

Total Synthesis of (±)-Iso-trans-trikentrin B

1998 ◽  
Vol 51 (3) ◽  
pp. 177 ◽  
Author(s):  
John K. MacLeod ◽  
Annemarie Ward ◽  
Anthony C. Willis
Keyword(s):  
Crystal Structure ◽  
Total Synthesis ◽  
Marine Sponge ◽  
Title Compound ◽  
Compound A ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Synthetic Sequence

The synthesis of the title compound, a member of a family of cyclopent[g]indoles isolated from a marine sponge, is described. Most of the synthetic sequence was developed starting from the more readily available cis-1,3-dimethylindan. An X-ray crystal structure of the indanol (24), the precursor of trans-1,3-dimethylindan, confirmed its relative stereochemistry.

scholarly journals The refinement of atomic parameters by the technique known in X-ray crystallography as ‘the method of steepest descents’

1949 ◽  
Vol 197 (1050) ◽  
pp. 336-355 ◽  
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Relaxation Method ◽  
Crystal Structure Analysis ◽  
Actual Structure ◽  
X Ray ◽  
X Ray Crystallography ◽  
Complete Discussion ◽  
General Configuration ◽  
Atomic Parameters

This paper is the first of a proposed set of three in which applications of the methods of ‘steepest descents’ are made to the problems of crystal structure analysis. The proposed programme is in three parts: (1) Working details of the method. (2) A discussion of the accuracy and convergence of the method. (3) Examples of the use of the method in actual structure determination. The present paper forms the first of this set and is complete in itself. A discussion of the normal methods of structure analysis results in a formulation of the problem as one of minimization, and leads naturally to the idea of optimum procedures for this purpose. Three techniques are derived from a unified presentation: ( a ) the ‘relaxation’ method, ( b ) the ‘least squares’ refinement, ( c ) the method of ‘steepest descents’. These are examined in detail and their virtues and defects noted. A complete discussion of the application of the steepest descent procedure to various types of structure analysis is given and techniques are derived for the cases of: refinement of a set of parameters already reasonably good; refinement of a structure where general configuration but not orientation is known; and refinement of structures given by electron densities on a lattice. Several variants of the process are given, in one of which only those planes of zero observed intensity being used; this gives a process which is independent of phase angle values and should be useful in the case of structures for which no chemical data is available.

scholarly journals Crystal Structure of Poly[(acetone-O)-3-((3,4-dimethoxyphenyl)(4-hydroxy-2-oxo-2H-chromen-3-yl)methyl)-(2-oxo-2H-chromen-4-olate)sodium]

2010 ◽  
Vol 2010 ◽  
pp. 1-7
Author(s):  
Anita Penkova ◽  
Pascal Retailleau ◽  
Ilia Manolov
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Orthorhombic System ◽  
Full Matrix ◽  
X Ray ◽  
X Ray Crystallography

The structure of Poly[(acetone-O)-3-((3,4-dimethoxyphenyl)(4-hydroxy-2-oxo-2H-chromen-3-yl)methyl)-(2-oxo-2H-chromen-4-olate)sodium] was determined by X-ray crystallography. The compound crystallizes in an orthorhombic system and was characterized thus P 21 21 21, a=9.967(2) Å, b=11.473(3) Å, c=22.176(5) Å. Z=4, V=2535.9(10) Å3. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F2 to final values of R1=0.0601 and wR2=0.1515.

Verfeinerung der Kristallstruktur von Tripalladium-di-tetrathiophospliat Pd3(PS4)2 Refinement of the Crystal Structure of Tripalladium-di-tetrathiophosphate Pda3(PS4)2

1983 ◽  
Vol 38 (4) ◽  
pp. 426-427 ◽  
Author(s):  
Arndt Simon ◽  
Karl Peters ◽  
Harry Hahn
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Title Compound ◽  
Type Structure ◽  
Tetrahedral Symmetry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Planar Environment

Abstract The structure of the title compound has been determined by X-ray crystallography. The title compound is synthesized from the elements at 600 °C. Its crystal structure, derived from powder data [3] is refined by single crystal diffractometer data. The structure is trigonal (P3̅ml, α = 684.1(1), c = 724.4(1) pm); Pd2+ cations and PS43- anions form a network with an anti-Claudetite (AS2O3) type structure. The PS4 units are distinctly distorted from ideal tetrahedral symmetry. The Pd atoms have a planar environment of 4 S atoms.

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