Sirosterol and dehydroazasirosterol, unusual steroidal adducts from a Sirococcus species

1992 ◽  
Vol 70 (7) ◽  
pp. 1905-1913 ◽  
Author(s):  
William A. Ayer ◽  
Yu-Ting Ma
Keyword(s):  
Double Bond ◽  
Monomethyl Ether ◽  
Spectroscopic Methods ◽  
Model Compounds ◽  
Shoot Blight ◽  
Selective Hydroxylation

Two unusual compounds, which are made up of a sterol portion fused at C-5 and C-6 to an atrovenetin-like part, have been isolated from a fungus that causes Sirococcus shoot blight of spruce. The structures of these compounds, sirosterol (4) and dehydroazasirosterol (13), were determined by spectroscopic methods and comparison with appropriate model compounds. Sirosterol is an adduct of ergosterol and atrovenetin (5) and dehydroazasirosterol is an adduct of 9(11)-dehydroergosterol and an azaatrovenetin. Both compounds give a monomethyl ether when treated with diazomethane and both have been transformed to the corresponding 3-ketosteroids. The preparation of the triol 6 resulting from the selective hydroxylation of the 5,6-double bond in ergosterol is described. A possible biogenesis of sirosterol from ergosterol endoperoxide and a desoxyatrovenetin is discussed.

Structure and Content of Dicyclopentadiene in Ethylene Propylene Dicyclopentadiene Terpolymers

1967 ◽  
Vol 40 (2) ◽  
pp. 563-568
Author(s):  
R. J. de Kock ◽  
A. Veermans
Keyword(s):  
Double Bond ◽  
Polymer Chain ◽  
Spectroscopic Methods ◽  
Double Bonds ◽  
Model Compounds ◽  
Ethylene Propylene ◽  
Infrared Spectroscopic ◽  
Polymerization Mixture ◽  
Derivatives Of

Abstract With the aid of model compounds—derivatives of endo- and exo-dicyclopentadiene—it has been established that a) the 9, 10-double bond (the double bond in the norbornane ring) is involved in the polymerization of dicyclopentadiene with ethylene and propylene, b) dicyclopentadiene, present in the polymerization mixture in the endo-configuration, occurs in the exo-configuration in the polymer chain. The same model compounds enable the dicyclopentadiene content of ethylene propylene dicyclopentadiene terpolymers to be determined by infrared spectroscopic methods. Use is made of the 3045 cm−1 band, which is characteristic of endo-cyclic double bonds in five-membered rings.

Configuration on the C=N double bond of monosubstituted amidines and amidoximes

1989 ◽  
Vol 54 (12) ◽  
pp. 3245-3252 ◽  
Author(s):  
Bernard Tinant ◽  
Janine Dupont-Fenfau ◽  
Jean-Paul Declercq ◽  
Jaroslav Podlaha ◽  
Otto Exner
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Steric Effects ◽  
Model Compounds ◽  
X Ray ◽  
Analogous Model

Configuration on the C=N double bond of amidines and amidoximes is controlled by steric effects on the second nitrogen atom but there is a difference in the case of N’-monosubstituted derivatives: amidines prefer E configuration (conformation around the C-N bond sp) and amidoximes Z configuration (conformation ap). This was confirmed by the X-ray structures of two analogous model compounds N,N’-dimethyl-4-nitrobenzamidine (monoclinic, P21c, a = 10.855(3), b = 11.043(3), c = 8.593(3) Å, β = 105.69(2)°, V = 991.8(5) Å3, Z = 4, Dx = 1.29 g cm-3, CuKα, λ = 1.5418 Å, μ = 7.91 cm-1, F(000) = 408, T = 291 K, R = 0.065 for 1 265 observed reflections) and N’-methyl-4-nitrobenzamidoxime (monoclinic, P21/a, a = 6.699(2), b = 24.178(9), c = 6.075(2) Å, β = 106.20(3)°, V = 944.9(6) Å3, Z = 4, Dx = 1.37 g cm-3, CuKα, λ = 1.5418 Å, μ =9.22 cm-1, F(000) = 408, T = 291 K, R = 0.079 for 1 278 observed reflections).

scholarly journals Phenolation of vegetable oils

2011 ◽  
Vol 76 (4) ◽  
pp. 591-606 ◽  
Author(s):  
Mihail Ionescu ◽  
Zoran Petrovic
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Double Bond ◽  
Vegetable Oils ◽  
Raw Materials ◽  
Complex Mixture ◽  
Double Bonds ◽  
Triflic Acid ◽  
Model Compounds ◽  
Phenol Alkylation

Novel bio-based compounds containing phenols suitable for the synthesis of polyurethanes were prepared. The direct alkylation of phenols with different vegetable oils in the presence of superacids (HBF4, triflic acid) as catalysts was studied. The reaction kinetics was followed by monitoring the decrease of the double bond content (iodine value) with time. In order to understand the mechanism of the reaction, phenol was alkylated with model compounds. The model compounds containing one internal double bond were 9-octadecene and methyl oleate and those with three double bonds were triolein and high oleic safflower oil (82% oleic acid). It was shown that the best structures for phenol alkylation are fatty acids with only one double bond (oleic acid). Fatty acids with two double bonds (linoleic acid) and three double bonds (linolenic acid) lead to polymerized oils by a Diels Alder reaction, and to a lesser extent to phenol alkylated products. The reaction product of direct alkylation of phenol with vegetable oils is a complex mixture of phenol alkylated with polymerized oil (30-60%), phenyl esters formed by transesterification of phenol with triglyceride ester bonds (<10 %) and unreacted oil (30%). The phenolated vegetable oils are new aromatic-aliphatic bio-based raw materials suitable for the preparation of polyols (by propoxylation, ethoxylation, Mannich reactions) for the preparation of polyurethanes, as intermediates for phenolic resins or as bio-based antioxidants.

Model Compounds Related to Saquayamycin. Attempts to Oxygenate the A/B Ring Junction

2002 ◽  
Vol 55 (5) ◽  
pp. 343 ◽  
Author(s):  
M. A. Apponyi ◽  
J. H. Bowie ◽  
B. W. Skelton ◽  
A. H. White
Keyword(s):  
Double Bond ◽  
Maleic Anhydride ◽  
Good Yield ◽  
Ring Opening ◽  
Diels Alder ◽  
Aromatic System ◽  
Model Compounds ◽  
Similar Treatment ◽  
Ring Junction

The aim of this project was to attempt to find a method for introducing the cis-dihydroxyl substitution at the A/B-ring junction of model compounds related to the saquayamycins. The Diels-Alder reactions of maleic anhydride and bromomaleic anhydride with 5,5-dimethyl-3-vinylcyclohexa-1,2-dienyl acetate gave the two required endo-adducts in good yield, namely (octahydrobenzo[e]isobenzofuran-9-yl acetate (6) and (octahydrobenzo[e]isobenzofuran-9-yl acetate (9). Each of these was converted into the B-ring mono-epoxide, namely (H-benzo[e]oxireno-2,3-furan-1-yl acetate (7) and a mixture of two racemic diastereoisomers of 9a-bromo-3,3-dimethyl-7,9-dioxoperhydrobenzo[e]oxi- reno[2,3-f]isobenzofuran-1-yl acetate (12), respectively. It was then hoped to deprotonate both (7) and (12) at the 9a position in order to effect migration of the 8,9 double bond to the 9,9a position. Reaction of (7) with a mild base (pyridine) did not effect any reaction. Similar treatment of (12) did remove the 9a proton, but it also effected ring opening of the epoxide, followed by dehydration and dehydrobromination to give an excellent (but unwanted) yield of the aromatized system (±)-7,7-dimethyl-1,3-dioxo-1,3,5,7-tetrahydrobenzo (e]isobenzofuran-9-yl acetate. Dehydrobromination of (9), and deprotonation of the 9a position, similarly formed the aromatic system (e]isobenzofuran-9-yl acetate (11) in good yield.

Role of the Protein Cavity in Phytochrome Chromoprotein Assembly and Double-bond Isomerization: A Comparison with Model Compounds

2010 ◽  
Vol 86 (4) ◽  
pp. 856-861 ◽  
Author(s):  
Thierry Rohmer ◽  
Christina Lang ◽  
Wolfgang Gärtner ◽  
Jon Hughes ◽  
Jörg Matysik
Keyword(s):  
Double Bond ◽  
Model Compounds ◽  
Double Bond Isomerization ◽  
Protein Cavity

scholarly journals Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration

2010 ◽  
Vol 6 ◽  
Author(s):  
Latif Kelebekli ◽  
Yunus Kara ◽  
Murat Celik
Keyword(s):  
Double Bond ◽  
Cyclization Reaction ◽  
Spectroscopic Methods ◽  
New Class ◽  
Hydrolysis Of

A new class of aminocyclitol derivatives with the bicyclo[4.2.0]octane skeleton was synthesized starting from cyclooctatetraene. Photooxygenation of trans-7,8-diacetoxy- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-diene afforded the bicyclic endoperoxides. Reduction of the latter with thiourea followed by a Pd(0) catalyzed ionization/cyclization reaction gave the corresponding oxazolidinone derivatives. Oxidation of the double bond with KMnO4 or OsO4 followed by acetylation gave the acetate derivatives, the exact configuration of which was determined by spectroscopic methods. Hydrolysis of the oxazolidinone rings and removal of the acetate groups furnished the desired aminocyclitols.

The Raman Spectra of Polybutadiene Rubbers

1970 ◽  
Vol 43 (2) ◽  
pp. 322-332 ◽  
Author(s):  
S. W. Cornell ◽  
J. L. Koenig
Keyword(s):  
Double Bond ◽  
Raman Spectra ◽  
Structure Type ◽  
Normal Coordinate ◽  
Model Compounds ◽  
Carbon Double Bond ◽  
Bond Stretching ◽  
Stretching Vibrations

Abstract The Raman spectra of cis-1,4-, trans-1,4-, and 1,2-polybutadiene are presented. Analysis of the spectra of these model compounds, and the normal coordinate results, enable the Raman frequencies to be classified by configurational structure type. The Raman carbon—carbon double bond stretching vibrations can be used to describe uniquely the structure content in polybutadienes.

Structure of Ethylene Propylene Dicyclopentadiene Terpolymers

1966 ◽  
Vol 39 (4) ◽  
pp. 964-968
Author(s):  
W. Cooper ◽  
D. E. Eaves ◽  
M. E. Tunnicloffe ◽  
G. Vaughan
Keyword(s):  
Double Bond ◽  
Infrared Spectra ◽  
Ring Opening ◽  
Iodine Monochloride ◽  
Model Compounds ◽  
Ethylene Propylene

Abstract Terpolymers of ethylene, propylenc and C14-dicyclopentadiene have been compared with model compounds to determine the structure of combined termonomer units. Reactions with iodine monochloride, bromine and the infrared spectra of the terpolymers indicate that dicyclopentadiene polymerizes at the 9,10 double bond without ring-opening or disproportionation.

Chemical studies of the Proteaceae. IV. The structures of the major phenols of Grevillea striata; a group of novel cyclophanes

1970 ◽  
Vol 23 (1) ◽  
pp. 147 ◽  
Author(s):  
DD Ridley ◽  
E Ritchie ◽  
WC Taylor
Keyword(s):  
Double Bond ◽  
Structure Determination ◽  
Ring System ◽  
Chemical Degradation ◽  
Aliphatic Chain ◽  
Spectroscopic Methods ◽  
Ether Extract ◽  
Phenolic Fraction ◽  
Saturated Chain ◽  
Chemical Studies

Attempts to separate the major constituents of the phenolic fraction of the ether extract of the wood of Grevillea striata R.Br. were unsuccessful, but by chemical degradation and spectroscopic methods the structures of four of the components were deduced. They were mono- and di-methyl ethers of 17,19,22,24- tetrahydroxy(l4-p-0-o)cyclophane with a double bond at either of two positions in the aliphatic chain. The new ring system was given the trivial name "turriane". Evidence that a fifth and a sixth component were derivatives with a saturated chain, and a seventh was a derivative of a double homologue of turriane, was obtained. Synthetic experiments connected with the structure determination, and on the synthesis of tetrahydroxyturriane are described. Possible biogenetic routes to striatol and the cyclophanes are discussed.

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