94487-88-4Relevant academic research and scientific papers
5-Hydroxy-4,5-Dihydropyrazoles
Zelenin, Kirill N.,Alekseyev, Valery V.,Tygysheva, Alja R.,Yakimovitch, Stanislav I.
, p. 11251 - 11256 (1995)
The use of β-diketones with strong electron-withdrawing substituents in reaction with hydrazine and its monosubstituted derivatives leads to the stable intermediates of pyrazole synthesis - 5-hydroxy-4,5-dihydropyrazoles or their open chain isomers.
5-Hydroxy-2-pyrazolines and some of their 1-substituted analogs
Zelenin,Tugusheva,Yakimovich,Alekseev,Zerova
, p. 668 - 676 (2007/10/03)
The use of 1,3-dicarbonyl compounds containing strong electron-withdrawing substituents (perfluoroalkyl, 4-nitrophenyl) at one of the carbonyl groups in reaction with hydrazine or its monosubstituted derivatives (4-nitro- and 2,4-dinitrophenylhydrazines) leads to the formation of stable intermediates for the synthesis of pyrazoles (5-hydroxy-2-pyrazolines) or their linear tautomers (hydrazones).
Synthesis of Pyrazole, 1,2,4,5-Tetrazine, and 1,2,4-Triazole Derivatives from Thiocarbonohydrazides and β-Dicarbonyl Compounds
Alekseev, V. V.,Zelenin, K. N.,Yakimovich, S. I.
, p. 868 - 873 (2007/10/03)
Reactions of acetylacetone, α-methylacetylacetone, and benzoyl- and 4-methoxybenzoylacetone with thiocarbonohydrazide yield corresponding pyrazoles with no substituent at N1.Reactions of 1-substituted thiocarbonohydrazides with acetylacetone, as well as of trifluoromethyl-substituted β-diketones and aroylacetones containing acceptor substituents with unsubstituted thiocarbonohydrazide, result in formation of corresponding 1-(N-aminothiocarbamoyl)-5-hydroxy-Δ5-pyrazolines which in some cases are converted into respective 1-(N-aminothiocarbamoyl)pyrazoles and further into 1-unsubstituted pyrazoles.Reaction of thiocarbonohydrazide with aroylacetaldehyde leads to 1,2,4,5-tetrazine-3-thiones.The product of reactions of 1,1,4-trimethylthiocarbonohydrazide with acetylacetone is a 1,2,4-triazole derivative.
INVESTIGATION OF THE MECHANISMS OF FORMATION OF HETEROCYCLES BY NMR SPECTROSCOPY. III. THE EFFECT OF ELECTRONIC FACTORS ON THE KINETICS OF THE DEHYDRATION OF DIHYDROXYPYRAZOLIDINES AND HYDROXYPYRAZOLINES- THE INTERMEDIATES IN THE REACTION OF HYDRAZINE WITH 1,3-DIKETONES
Selivanov, S. I.,Golodova, K. G.,Abbasov, Ya. A.,Ershov, B. A.
, p. 1361 - 1364 (2007/10/02)
The rate constants for the dehydration of the dihydroxypyrazolidine and hydroxypyrazoline intermediates in the reaction of hydrazine with substituted benzoylacetones p-XC6H4COCH2COCH3 (X= CH3O, CH3, H, Cl, NO2) in methanol were determined by NMR spectroscopy using the stopped-flow technique.Increase in the electronegativity of the substituent leads, on the one hand, to an increase in the contribution from the reaction path involving the formation of the tautomeric pyrazoles with the participation of 3-methyl-5-(p-XC6H4)-5-hydroxypyrazoline and, on the other hand, to an increase in the rate of its conversion into the corresponding pyrazole.Analysis of the relationships between the dehydration rates and the Hammett ? constants confirms a reaction mechanism with the participation of the cyclic dihydroxypyrazolidine intermediate.
