Synthesis and structure of new trichloromethyl-β-diketones — 5-Trichloromethylisoxazole and 5-isoxazolecarboxylic acid derivatives

2005 ◽  
Vol 83 (8) ◽  
pp. 1171-1177 ◽  
Author(s):  
Marcos A.P Martins ◽  
Sergio Brondani ◽  
Victor L Leidens ◽  
Darlene C Flores ◽  
Sidnei Moura ◽  
...  
Keyword(s):  
Hydroxylamine Hydrochloride ◽  
Enol Form ◽  
Improved Method ◽  
Keto Form ◽  
Dicarbonyl Compounds ◽  
Multinuclear Nmr ◽  
Nmr Study

An improved method for the synthesis of a new series of trichloromethyl-β-diketones including 1,1,1-trichloropentan-2,4-dione (2a), 1,1,1-trichloro-3-methylhexan-2,4-dione (2b), 4,4,4-trichloro-1-phenylbutan-1,3-dione (2c), 4,4,4-trichloro-2-methyl-1-phenylbutan-1,3-dione (2d), 2-trichloroacetylcyclohexanone (2e), 4-tert-butylcyclohexanone (2f), 4-tert-butylcycloheptanone (2g), and 4-tert-butylcyclooctanone (2h) is reported. A multinuclear NMR study showed that β-dicarbonyl compounds 2b and 2d–2h are predominantly in the keto form and 2a and 2c are in the enol form. The trichloromethyl-β-diketones react with hydroxylamine hydrochloride leading to three sets of isoxazole derivatives.Key words: acetals, acylation, trichloromethyl-1,3-diketones, 2-trichloroacetylcycloalkanones, isoxazoles, cyclocondensation.

Arylation of enelactams using TIPSOTf: reaction scope and mechanistic insight

2021 ◽  
Author(s):  
Tomasz J. Idzik ◽  
Zofia M. Myk ◽  
Łukasz Struk ◽  
Magdalena Perużyńska ◽  
Gabriela Maciejewska ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Multinuclear Nmr ◽  
Mechanistic Insight ◽  
Nmr Study ◽  
Wide Range

Triisopropylsilyltrifluoromethanesulfonate can be effectively used for the arylation of a wide range of enelactams. The multinuclear NMR study provided deep insights into the reaction mechanism.

scholarly journals 21Ne and 131Xe NMR study of electric field gradients and multinuclear NMR study of the composition of a ferroelectric liquid crystal

2018 ◽  
Vol 149 (23) ◽  
pp. 234901 ◽  
Author(s):  
Susanna K. Ahola ◽  
Petri Ingman ◽  
Reino Laatikainen ◽  
Jari Sinkkonen ◽  
Jukka Jokisaari
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Ferroelectric Liquid Crystal ◽  
Electric Field Gradients ◽  
Multinuclear Nmr ◽  
Field Gradients ◽  
Nmr Study

Phototransformation products of the alkaloid lappaconitine: Multinuclear NMR study

2008 ◽  
Vol 197 (2-3) ◽  
pp. 290-294 ◽  
Author(s):  
Nikolay E. Polyakov ◽  
Tatyana V. Leshina ◽  
Alexey V. Tkachev ◽  
Irina A. Nikitina ◽  
Natalia A. Pankrushina
Keyword(s):  
Multinuclear Nmr ◽  
Nmr Study

Multinuclear NMR Study on the Sol–Gel Transition of Aqueous κ- and λ-carrageenan Solutions: Selective Site Binding of Group I Cations

2000 ◽  
Vol 39 (Part 1, No. 7A) ◽  
pp. 4094-4099
Author(s):  
Masahiko Annaka ◽  
Kiriko Suzuki ◽  
Ryoko Takahashi ◽  
Takayuki Nakahira ◽  
Masayuki Tokita ◽  
...  
Keyword(s):  
Sol Gel ◽  
Multinuclear Nmr ◽  
Nmr Study ◽  
Group I ◽  
Sol Gel Transition ◽  
Site Binding ◽  
Gel Transition

In Situ High Temperature Multinuclear NMR Study of Clinker Formation

1998 ◽  
pp. 47-55
Author(s):  
Laurent Bonafous ◽  
Catherine Bessada ◽  
Dominique Massiot ◽  
Jean-Pierre Coutures ◽  
Bruno LeRolland ◽  
...  
Keyword(s):  
High Temperature ◽  
Multinuclear Nmr ◽  
Nmr Study

Crystal structure, spectroscopic studies and theoretical studies of thiobarbituric acid derivatives: understanding the hydrogen-bonding patterns

2018 ◽  
Vol 74 (12) ◽  
pp. 1703-1714 ◽  
Author(s):  
Anamika Sharma ◽  
Sizwe J. Zamisa ◽  
Sikabwe Noki ◽  
Zainab Almarhoon ◽  
Ayman El-Faham ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Materials Science ◽  
Thiobarbituric Acid ◽  
Intramolecular Hydrogen Bonding ◽  
Spectroscopic Studies ◽  
Enol Form ◽  
Keto Form ◽  
X Ray Crystallography ◽  
Schiff Base Formation ◽  
Intramolecular Hydrogen

In addition to their wide-ranging applications in the pharmaceutical industry, thiobarbituric acid (TBA) derivatives are also known to possess applications in engineering and materials science. 20 TBA derivatives, with diversity at the N and C-5 positions through acylation, Schiff base formation, Knoevenagel condensation, thioamide and enamine formation, were studied. The absolute configurations for six derivatives, namely 5-acetyl-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, C10H14N2O3S, A01, 1,3-diethyl-5-propionyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, C11H16N2O3S, A02, tert-butyl [1-(1,3-diethyl-4,6-dioxo-2-thioxohexahydropyrimidin-5-yl)-3-methyl-1-oxobutan-2-yl]carbamate, C18H29N3O5S, A06, 1,3-diethyl-4,6-dioxo-2-thioxo-N-(p-tolyl)hexahydropyrimidine-5-carbothioamide, C16H19N3O2S2, A13, 5-(1-aminoethylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, C10H15N3O2S, A17, and 5-(1-aminopropylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, C11H17N3O2S, A18, were confirmed by single-crystal X-ray crystallography, which indicates the formation of intramolecular hydrogen bonding in all six cases and intermolecular hydrogen bonding for A17. In A13, the presence of two intramolecular hydrogen bonds was observed. The stabilization of the enol form over the keto form was confirmed by computation. In order to convert the keto form to the enol form, an energy barrier of 55.05 kcal mol−1 needs to be overcome, as confirmed by transition-state calculations.

Dynamisches Verhalten dimerer 1,3,2,4λ2-Diazasilastannetidine und -plumbetidine in Lösung — eine Multikern-NMR-Studie/Dynamic Behaviour of Dimeric 1,2,3,4λ2-Diazasilastannetidines and -plumbetidines in Solution — a Multinuclear NMR Study

1989 ◽  
Vol 44 (3) ◽  
pp. 288-292 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Klaus Horchler ◽  
Hong Zhou ◽  
Michael Veith
Keyword(s):  
Low Temperature ◽  
Dynamic Process ◽  
Room Temperature ◽  
Dynamic Behaviour ◽  
The Other ◽  
Multinuclear Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
Intramolecular Process

1,3-Diisopropyl-2,2-dimethyl-1,3,2,4λ2-diazasilastannetidine (1b) and -plumbetidine (2b) are dimeric [(1b)2, (2b)2] in solution. At room temperature the structure of (1b)2 is fluxional. The dynamic behaviour is interpreted - on the basis of 1H. 13C, 29Si and 119Sn NMR data - as an intramolecular process in which the four-membered rings keep their identity. Such a process involves either concerted opening of the two coordinative Sn - N bonds and mutual slippage of the two rings, or consecutive cleavage of one of the coordinative Sn - N bonds and rotation about the other one. At room temperature the dimer (2b)2 is in equilibrium with its monomer 2b, whereas at low temperature the dynamic process corresponds to that established for (1b)2. In solutions which contain a mixture of the dimers (1b)2 and (2b)2, the presence of the mixed dimer 1b/2b can be proved unambiguously by consistent 29Si, 119Sn and 207Pb NMR data.

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