Synthesis of the Troponoid Natural Product Nezukone Via Sequential Rearrangement of Two Isomeric Precursors

1993 ◽  
Vol 46 (12) ◽  
pp. 1941 ◽  
Author(s):  
MG Banwell ◽  
CJ Cowden ◽  
GL Gravatt ◽  
CEF Rickard
Keyword(s):  
Crystal Structure ◽  
Natural Product ◽  
X Ray ◽  
Key Features

Nezukone (1) has been synthesized in seven steps from the readily available Δ3-trinorcarene (4). Key features of the sequence used include formation of the bicyclic isomer (2) of compound (1). Base-promoted isomerization of compound (2) followed by acidic workup then produced the isolable but highly unstable heptafulvenol (3), an extended enolic tautomer of nezukone (1). Under mildly basic conditions compound (3) rearranged to give the natural product (1). The X-ray crystal structure of the ring-fused cyclobutanone (8) is reported.

scholarly journals Crystal structure of 5-[(benzoyloxy)methyl]-5,6-dihydroxy-4-oxocyclohex-2-en-1-yl benzoate

2020 ◽  
Vol 76 (7) ◽  
pp. 1096-1100
Author(s):  
Theerachart Leepasert ◽  
Patchreenart Saparpakorn ◽  
Kittipong Chainok ◽  
Tanwawan Duangthongyou
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Natural Product ◽  
Dihedral Angle ◽  
Absolute Configuration ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ring Form

The crystal structure of the natural product zeylenone, C21H18O7, was confirmed by single-crystal X-ray diffraction. The crystal structure has three chiral centers at positions C1, C5 and C6 of the cyclohexanone ring, but the absolute configuration could not be determined reliably. The methyl benzoate and benzoyloxy substituents at positions C1 and C5 of the cyclohexenone ring are on the same side of the ring with the dihedral angle between their mean planes being 16.25 (10)°. These rings are almost perpendicular to the cyclohexenone ring. The benzoate groups and two hydroxyl groups on the cyclohexenone ring form strong hydrogen bonds to consolidate the crystal structure. In addition, weak C—H...O hydrogen bonds also contribute to the packing of the structure.

Pigments of Fungi. XLVIII Clavorubin from Two Australasian Toadstools of the Genus Cortinarius and the X-Ray Crystal Structure of the Methyl Ester of 6-O-Methylclavorubin

1998 ◽  
Vol 51 (5) ◽  
pp. 347 ◽  
Author(s):  
Melvyn Gill ◽  
Malcolm S. Buchanan ◽  
Peter J. Steel ◽  
Nives M. Milanovic ◽  
Somphone Phonh-Axa
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Single Crystal ◽  
Natural Product ◽  
Structure Analysis ◽  
Claviceps Purpurea ◽  
Chemical Methods ◽  
X Ray ◽  
First Time

Clavorubin (1,5,6,8-tetrahydroxy-3-methyl-9,10-dioxoanthracene-2-carboxylic acid) (1), previously known only from the ascomycetious rye fungus Claviceps purpurea (‘ergot’), has been isolated from the fruit bodies of two Australasian basidiomycetes belonging to the genus Cortinarius and characterized by spectroscopic and chemical methods. A single-crystal X-ray structure analysis of the methyl ester (4) of 6-O-methylclavorubin establishes unequivocally, for the first time, the structure of the natural product.

The Palladium-Mediated Cross Coupling of Bromotropolones With Organostannanes or Arylboronic Acids: Applications to the Synthesis of Natural Products and Natural Product Analogs

1991 ◽  
Vol 44 (5) ◽  
pp. 705 ◽  
Author(s):  
MG Banwell ◽  
JM Cameron ◽  
MP Collis ◽  
GT Crisp ◽  
RW Gable ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Natural Products ◽  
Natural Product ◽  
Cross Coupling ◽  
Binding Activity ◽  
X Ray ◽  
Arylboronic Acids ◽  
Wide Range ◽  
Tubulin Binding

The bromotropolones (4), (5) and (10) undergo palladium-mediated cross coupling with a wide range of organostannanes to produce alkenyl -, alkyl- and aryl-substituted tropolones . The methodology has been applied to the synthesis of the monoterpenes β- dolabrin (11),β- thujaplicin (12), 4-isopropyl-7-methoxytropolone (13) and β- thujaplicinol (14). Cross coupling of bromotropolones (4), (5) and (10) with various aryltrimethylstannanes or arylboronic acids has permitted the preparation of the bicyclic colchicine analogues (30)-(43) which have been tested for tubulin -binding activity. The X-ray crystal structure of the most active of these systems, compound (38), is reported.

Crystal Structure of 1-Methyl-5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione

2005 ◽  
Vol 58 (8) ◽  
pp. 600 ◽  
Author(s):  
Brian W. Skelton ◽  
Matthew J. Piggott
Keyword(s):  
Crystal Structure ◽  
Natural Product ◽  
X Ray

The X-ray crystal and modelled structures of the natural product 1-methyl-5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione are presented. These data, in conjunction with modelling of the natural product ventilone G, confirm the preference for the 5,8-dihydroxynaphtho[2,3-c]furan-4,9-dione tautomers over those containing an isobenzofuran moiety and necessitate revision of the published structures of ventilone F and G.

Pigments of Fungi. XLVII. Cardinalic Acid, a New Anthraquinone Carboxylic Acid from the New Zealand Toadstool Dermocybe cardinalis and the Synthesis and X-Ray Crystal Structure of Methyl 1,7,8-Tri-O-methylcardinalate

1998 ◽  
Vol 51 (3) ◽  
pp. 213 ◽  
Author(s):  
Melvyn Gill ◽  
Peter M. Morgan ◽  
Jin Yu ◽  
Jonathan M. White
Keyword(s):  
Crystal Structure ◽  
New Zealand ◽  
Carboxylic Acid ◽  
Single Crystal ◽  
Natural Product ◽  
Carboxylic Acids ◽  
Structure Analysis ◽  
Diels Alder ◽  
Cycloaddition Reactions ◽  
X Ray

Cardinalic acid (1,7,8-trihydroxy-6-methoxy-3-methyl-9,10-dioxoanthracene-2-carboxylic acid) (4) and the known anthraquinone carboxylic acids endocrocin (1), dermolutein (2) and cinnalutein (3) have been isolated from the New Zealand toadstool Dermocybe cardinalis. Methyl 1,7,8-tri-O-methylcardinalate (5) has been prepared both by permethylation of the natural product (4) and from 2,6-dichloro-1,4-benzoquinone by two consecutive regioselective Diels–Alder cycloaddition reactions. A single-crystal X-ray structure analysis of the ester (5) corroborates the structure of the natural product (4) and confirms the outcome of both cycloaddition reactions.

scholarly journals Isolation and crystal structure of lawinal

2021 ◽  
Vol 77 (1) ◽  
pp. 75-78
Author(s):  
Virayu Suthiphasilp ◽  
Pornphimol Meesakul ◽  
Christopher Richardson ◽  
Stephen G. Pyne ◽  
Surat Laphookhieo
Keyword(s):  
Crystal Structure ◽  
Natural Product ◽  
Absolute Configuration ◽  
Specific Rotation ◽  
Stereochemical Assignment ◽  
X Ray ◽  
Π Interactions ◽  
Independent Molecules ◽  
The Absolute ◽  
Hydrogen Bonded

The structure of the natural product lawinal [systematic name: (−)-(2S)-5,7-dihydroxy-6-methyl-4-oxo-2-phenylchromane-8-carbaldehyde, C17H14O5] at 150 K is reported. The compound crystallizes with monoclinic (I2) symmetry and with Z′ = 2. The absolute configuration could not be determined reliably from X-ray analysis only. However, our analysis returns the S-configuration at the C-2 position, consistent with previous stereochemical assignment from specific rotation. The independent molecules form into alternating hydrogen-bonded chains with C—H...O=CH intermolecular linkages that run parallel to the crystallographic a axis and are extended into the ac plane by π–π interactions between their phenyl substituents.

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

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