On the structure and reactivity of a stabilized phosphorane: methyl (triphenylphosphoranylidene) acetate

1990 ◽  
Vol 68 (12) ◽  
pp. 2123-2128 ◽  
Author(s):  
Margaret H. Kayser ◽  
Donald L. Hooper
Keyword(s):  
Phthalic Anhydride ◽  
Carbonyl Compounds ◽  
Room Temperature ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans

In the absence of a source of acidic protons, methyl (triphenylphosphoranylidene)acetate 1 exists as a mixture of the cis and trans isomers even at room temperature. Acidic protons catalyze the interconversion of the two forms and facilitate the reaction of the ylide with active carbonyl compounds such as benzaldehyde or phthalic anhydride. Keywords: stabilized phosphoylide, structure, reactivity.

Some reactions of 2,4-dimethoxytetrahydropyrans

1969 ◽  
Vol 47 (17) ◽  
pp. 3099-3106 ◽  
Author(s):  
M. J. Baldwin ◽  
R. K. Brown
Keyword(s):  
Room Temperature ◽  
Equilibrium Mixture ◽  
Anomeric Effect ◽  
Temperature Reaction ◽  
Trans Isomers ◽  
Kcal Mole ◽  
A Value ◽  
Cis And Trans Isomers ◽  
Acid Catalyzed ◽  
Cis And Trans

Acid-catalyzed elimination of methanol from 2,4-dimethoxytetrahydropyran (1) produces 2-methoxy-5,6-dihydro-2H-pyran (3) rather than the expected olefin 4-methoxy-3,4-dihydro-2H-pyran (2).The reaction of 1,3-dibromo-5,5-dimethylhydantoin with 3 in ether – methanol gives a 2:1 mixture of the isomers 3β-bromo-2α,4α-dimethoxytetrahydropyran (5a) and 3α-bromo-2α,4β-dimethoxytetrahydropyran (5b) respectively. A rationale is given to explain the preponderance of 5a over 5b and the highly selective attack of the bromine of the hydantoin and the methanol on C-3 and C-4 respectively of the double bond of 3. Reduction of 5ab with zinc in ethanol provides only compound 3.The room temperature reaction of 1 in a mixture of water and 1,2-dimethoxyethane containing Amberlite IR-120, produces 2-hydroxy-4-methoxytetrahydropyran (6) as an equilibrium mixture of cis and trans isomers in the ratio 1:1. This gave a value of 0.9 kcal/mole for the anomeric effect in 6. Pyrolysis of the derivative, 2-acetoxy-4-methoxytetrahydropyran failed to produce the olefin 2 and resulted only in extensive decomposition.

Synthese von Silicium-Phosphor-Ringen - Struktur eines cis-2.2.4.4-Tetrakis(silylamino)-1.3-diphospha-2.4-disilacyclobutans / Synthesis of Silicon-Phosphorus-Rings - Structure of a cis-2,2,4,4-Tetrakis(silylamino)-1,3-diphospha-2,4-disilacyclobutane

1983 ◽  
Vol 38 (12) ◽  
pp. 1557-1562 ◽  
Author(s):  
Uwe Klingebiel ◽  
Norbert Vater ◽  
William Clegg ◽  
Martin Haase ◽  
George M. Sheldrick
Keyword(s):  
Crystal Structure ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Molar Ratio ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
By Products ◽  
Cis Isomer

Fluorosilylphosphanes of the type R2SiFPHR′ (R = CHMe2, CMe3, NMeSiMe3; R′ = H, C6H5; 1-4) are obtained in the reaction of difluorosilanes with lithiated phosphanes in a molar ratio 1:1. Diphosphasilanes (5, 6) and a difluorosilylphosphane (7) are isolated as by-products. 1-4 react with n-C4H9Li to give cyclic silylphosphanes, LiF, and C4H10 (8-11). Dilithiated 5 reacts with F2PN(CMe3)SiMe3 to form of a four-membered SiP3-ring 12. The 31P NMR spectra of 9 and 11 show signal coalescence for the cis-and trans-isomers at room temperature. The crystal structure of the cis-isomer of 11 has been determined. The substituted ring 13 is prepared in the reaction of lithiated 9 and Me2SiF2

Adduct Intermediates in the Side-chain Nitration of 1,4-Dimethylnaphthalene

1972 ◽  
Vol 50 (24) ◽  
pp. 3988-3992 ◽  
Author(s):  
Alfred Fischer ◽  
Alan Leslie Wilkinson
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Acetic Anhydride ◽  
Room Temperature ◽  
Methylene Chloride ◽  
Side Chain ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans ◽  
Naphthyl Acetate

cis and trans isomers of 1,4-dimethyl-4-nitro-1,4-dihydro-1-naphthyl acetate (1) have been isolated from a mixture of 1,4-dimethylnaphthalene and nitric acid in acetic anhydride by quenching at −40°. At room temperature only 1-methyl-4-nitromethylnaphthalene (4) is obtained. The conversion of 1,4-dimethylnaphthalene to 4 and of the cis (1a) and trans (1b) adducts to 4, by nitric acid in acetic anhydride, has been followed by n.m.r. 1,4-Dimethyl-4-nitro-1,4-dihydro-1-naphthyl nitrate (5) appears to be the immediate product from nitration of 1,4-dimethylnaphthalene in acetic anhydride, methylene chloride, or nitromethane. In acetic anhydride 5 is converted into 1. Decomposition of 1 in acetic acid gives 1,4-dimethyl-2-naphthyl acetate and some 4. The formation of 4 in this reaction is suppressed by urea.

Acid-catalysed isomerization of ethyl 5-Hydroxy-7a-methyl-1-oxo-2,6,7,7a tetrahydro-1H-indene-4-carboxylate

1977 ◽  
Vol 30 (2) ◽  
pp. 443 ◽  
Author(s):  
DJ Collins ◽  
CW Tomkins
Keyword(s):  
Hydrogen Chloride ◽  
Room Temperature ◽  
Chloroform Solution ◽  
Trans Isomers ◽  
Cis And Trans Isomers ◽  
Cis And Trans

Treatment of a chloroform solution of ethyl 5-hydroxy-7a-methyl-1-oxo- 2,6,7,7a-tetrahydro-1H-indene-4-carboxylate with dry hydrogen chloride at room temperature gave ethyl 5-hydroxy-7a-methyl-1-oxo-cis-3a,6,7,7a- tetrahydro-1H-indene-4-carboxylate, and the corresponding trans-hydrindan in the ratio 9 : 1. Hydrogenation of this mixture gave ethyl 5-hydroxy-7a-methyl-1-oxo-cis-3a,6,7,7a-tetrahydroindan-4-carboxylate, and ethyl t-7a-methyl-1,5-dioxo-r-3a,4,5,6,7,7a-hexa-hydroindan-c-4a- carboxylate, which were characterized by conversion into the cis and trans isomers of 7a-methylperhydroindan-1,5-dione, respectively.

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
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