Flavan derivatives. XVIII. Synthesis of hemiketals containing the peltogynol ring system: 3(3')-Hydroxyisochromano (4',3':2, 3) chromans. Conversion of 2'-hydroxychdcones into flav-3-enes and its biosyntheticimplications

1967 ◽  
Vol 20 (10) ◽  
pp. 2169
Author(s):  
JW Clark-Lewis ◽  
DC Skingle
Keyword(s):  
Biosynthetic Pathway ◽  
Ring System ◽  
Mechanism Of Formation ◽  
Biological Reduction ◽  
Mass Spectral ◽  
Lithium Aluminium ◽  
Cis And Trans Isomers ◽  
New Synthesis ◽  
Trimethyl Ether ◽  
Cis And Trans

Reduction of three 1?-oxoisochromeno(4?,3?:2,3)chromones [chromeno(3?,2?: 3,4)isocoumarins] with lithium aluminium hydride has been shown to yield 3(3?)-hydroxyisochromano(4?,3?:2,3)chromans (hemiketals). The structures of these compounds (the 7-methoxy, 7,6?,7?-trimethoxy, and parent hemiketals) were unequivocally established by N.M.R., mass spectral, and chemical data. The hemiketals contain the peltogynol ring system, and one of them is the 7,6?,7?- trimethyl ether of the structure originally proposed for this leucoanthocyanidin by Robinson and Robinson. The hemiketals were obtained as mixtures of cis- and trans- isomers which underwent equilibration in deuterochloroform or in wet chloroform, and configurations were assigned to the isomers from a detailed study of their N.M.R. spectra. The hemiketals suffered dehydration when heated further in deuterochloroform, and gave the isochromeno(4?,3?:2,3)chromens (flav-2-enes), which immediately gave the flavylium salts with cold acids in air. The flavylium salts were also formed very readily from the hemiketals and acid, and the trimethoxy- henliketal gave the peltogynidin trimethyl ether cation. In connection with the mechanism of formation of the hemiketals from chromenoisocoumarins it was found that 2?-hydroxychalcones are reduced by sodium borohydride to flav-3-enes, and these readily give anthocyanidins when treated with acid. Parallel biological reduction of chalcones is clearly possible and a plausible, new, biosynthetic pathway leading directly from 2?-hydroxychalcones to anthocyanidins and catechins is proposed. Flav-3-enes are valuable intermediates for preparation of flavans, flavan derivatives, and flavylium salts, and the new synthesis makes flav-3-enes readily accessible in one stage from 2?-hydroxychalcones.

Identification of cis- and trans-1,1,2,3,4-PentachIoro-4-[1-methylethoxy]-l,3-butadiene Residues in Mississippi River Fish

1986 ◽  
Vol 69 (4) ◽  
pp. 586-591
Author(s):  
Martin P Yurawecz ◽  
Jo-Yun T Chen ◽  
Bartholomew J Puma
Keyword(s):  
Mississippi River ◽  
Organophosphorus Pesticides ◽  
Reaction Products ◽  
Trans Isomers ◽  
Mass Spectral ◽  
Cis And Trans Isomers ◽  
Florisil Column Chromatography ◽  
Aoac Method ◽  
The Individual ◽  
Cis And Trans

Abstract The cis- and trans-isomers of 1,1,2,3,4-pentachloro-4-[1-methylethoxy]-1,3-butadiene have been identified as contaminants in fish caught from the Mississippi River at St. Louis, MO, and as far as 150 miles south of that location. Up to 0.1 ppm of the cis-isomer and 0.8 ppm of the trans-isomer were determined by using a method based on the AOAC multiresidue method for detecting organochlorine and organophosphorus pesticides. In tests of the modified AOAC method on spiked fish, both isomers were quantitatively recovered (95-106%). A mixture of the cis- and trans-isomers was synthesized by reacting hexachlorobutadiene with sodium isopropoxide. Separation of the reaction products by Florisil column chromatography provided reference standards of the individual isomers for identification and quantitation of the residues. The stereospecificity of the synthesis reaction and the infrared and mass spectral data used to verify the structures of the products are discussed.

Flavan derivatives. XIII. The formation of 1,3-Diarylpropan-2-ols and 2,3-Diarylpropan-1-ols from Flavan-3-ols

1965 ◽  
Vol 18 (3) ◽  
pp. 389 ◽  
Author(s):  
JW Clark-Lewis ◽  
GC Ramsay
Keyword(s):  
Molecular Complex ◽  
Liquid Ammonia ◽  
Reduction Method ◽  
Optical Purity ◽  
Specific Rotation ◽  
Aluminium Chloride ◽  
Lithium Aluminium Hydride ◽  
Mechanism Of Formation ◽  
Lithium Aluminium ◽  
Trimethyl Ether

No change in specific rotation of (-)-1-(3,4-dimethoxyphenyl)-3-(2,4,6- trimethoxyphenyl)propan-2-ol was observed during attempted resolution, so that the propanol is probably close to optical purity in spite of its low specific rotation. (-)-Epigallocatechin pentamethyl ether was reduced with sodium and liquid ammonia to an analogous hexamethoxydiarylpropan-2-ol. Several conditions for reducing ( +)-catechin tetramethyl ether with lithium aluminium hydride-aluminium chloride mixtures were examined, and the reduction method was applied to (-)- epiafzelechin trimethyl ether and to (-)-epigallocatechin pentamethyl ether. The mechanism of formation of the (-)-2,3-diarylpropan-1-ol from (+)-catechin and (-)-epicatechin tetramethyl ethers is discussed. The 5,7,4'-trimethyl ethers of (-)-epiafzelechin and (�)-dihydrokaempferol were found to form a 1 : 1 molecular complex.

scholarly journals Identification of Anthocyanin Compounds in Butterfly Pea Flowers (Clitoria ternatea L.) by Ultra Performance Liquid Chromatography/Ultraviolet Coupled to Mass Spectrometry

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4539
Author(s):  
Nguyen Minh Thuy ◽  
Vo Minh ◽  
Tran Ben ◽  
My Tuyen Thi Nguyen ◽  
Ho Ha ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Ultra Performance Liquid Chromatography ◽  
Negative Ion ◽  
Trans Isomers ◽  
Clitoria Ternatea ◽  
Flower Extract ◽  
Cis And Trans Isomers ◽  
Butterfly Pea ◽  
Cis And Trans

Butterfly pea flower have great sensory attraction, but they have not yet been used widely in Vietnam. Extracts of butterfly pea flowers can be used conveniently as a natural blue colorant for food products. In this study, the identification of anthocyanin compounds in butterfly pea flowers was performed by UPLC coupled with a UV and Mass spectrometer instrument. Positive and negative ion electrospray MS/MS chromatograms and spectra of the anthocyanin compounds were determined. By analyzing the chromatograms and spectra for each ion, five anthocyanins were identified in the butterfly pea flower extract; these were delphinidin-3-(6”‐p-coumaroyl)-rutinoside, cyanidin 3-(6”-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl) glucose in both cis- and trans- isomers, cyanidin-3-(p-coumaroyl-glucoside) and delphinidin-3-pyranoside. Additionally, based on their intensity, it was determined that cyanidin-3-(p-coumaroyl-glucoside) was the most abundant anthocyanin, followed by cyanidin 3-(6”-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl-glucoside), delphinidin-3-(6”-p-coumaroyl)-rutinoside and delphinidin-3-pyranoside. In this study, cyanidin derivatives were discovered in butterfly pea flower extract, where these compounds had not been detected in previous studies.

Unveiling the coexistence of cis- and trans-isomers in the hydrolysis of ZrO2: A coupled DFT and high-resolution photoelectron spectroscopy study

2020 ◽  
Vol 153 (24) ◽  
pp. 244308
Author(s):  
Ali Abou Taka ◽  
Mark C. Babin ◽  
Xianghai Sheng ◽  
Jessalyn A. DeVine ◽  
Daniel M. Neumark ◽  
...  
Keyword(s):  
High Resolution ◽  
Photoelectron Spectroscopy ◽  
Spectroscopy Study ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Hydrolysis Of

scholarly journals Increases in plasma trans-EETs and blood pressure reduction in spontaneously hypertensive rats

2011 ◽  
Vol 300 (6) ◽  
pp. H1990-H1996 ◽  
Author(s):  
Houli Jiang ◽  
John Quilley ◽  
Anabel B. Doumad ◽  
Angela G. Zhu ◽  
John R. Falck ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Spontaneously Hypertensive Rat ◽  
Blood Pressure Reduction ◽  
Maximal Velocity ◽  
Spontaneously Hypertensive ◽  
Cis And Trans Isomers ◽  
Wistar Kyoto Rat ◽  
Wistar Kyoto ◽  
Cis And Trans ◽  
Cis Isomer

Epoxyeicosatrienoic acids (EETs) are vasodilator, natriuretic, and antiinflammatory lipid mediators. Both cis- and trans-EETs are stored in phospholipids and in red blood cells (RBCs) in the circulation; the maximal velocity ( Vmax) of trans-EET hydrolysis by soluble epoxide hydrolase (sEH) is threefold that of cis-EETs. Because RBCs of the spontaneously hypertensive rat (SHR) exhibit increased sEH activity, a deficiency of trans-EETs in the SHR was hypothesized to increase blood pressure (BP). This prediction was fulfilled, since sEH inhibition with cis-4-[4-(3-adamantan-1-ylureido)cyclohexyloxy]benzoic acid (AUCB; 2 mg·kg−1·day−1 for 7 days) in the SHR reduced mean BP from 176 ± 8 to 153 ± 5 mmHg ( P < 0.05), whereas BP in the control Wistar-Kyoto rat (WKY) was unaffected. Plasma levels of EETs in the SHR were lower than in the age-matched control WKY (16.4 ± 1.6 vs. 26.1 ± 1.8 ng/ml; P < 0.05). The decrease in BP in the SHR treated with AUCB was associated with an increase in plasma EETs, which was mostly accounted for by increasing trans-EET from 4.1 ± 0.2 to 7.9 ± 1.5 ng/ml ( P < 0.05). Consistent with the effect of increased plasma trans-EETs and reduced BP in the SHR, the 14,15- trans-EET was more potent (ED50 10−10 M; maximum dilation 59 ± 15 μm) than the cis-isomer (ED50 10−9 M; maximum dilation 30 ± 11 μm) in relaxing rat preconstricted arcuate arteries. The 11,12-EET cis- and trans-isomers were equipotent dilators as were the 8,9-EET isomers. In summary, inhibition of sEH resulted in a twofold increase in plasma trans-EETs and reduced mean BP in the SHR. The greater vasodilator potency of trans- vs. cis-EETs may contribute to the antihypertensive effects of sEH inhibitors.

PREPARATION OF ERUCIC AND NERVONIC ACIDS LABELLED WITH CARBON-14

1957 ◽  
Vol 35 (8) ◽  
pp. 757-760 ◽  
Author(s):  
K. K. Carroll
Keyword(s):  
Enoic Acid ◽  
Nervonic Acid ◽  
Malonic Ester ◽  
Ester Synthesis ◽  
Trans Isomers ◽  
Carbon 14 ◽  
Cis And Trans Isomers ◽  
Cis And Trans

The malonic ester synthesis of nervonic acid (tetracos-15-enoic acid) has been modified so that the product consists of pure cis rather than a mixture of cis and trans isomers. The modified synthesis has been used for the preparation of C14-labelled erucic and nervonic acids.

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