Reaction of the hydrazides of aromatic and pyridine-3(4)-carboxylic acids with 4-ethoxy-1,1,1-tri-fluorobut-3-en-2-one leads to the formation of derivatives having a 5-hydroxy-2-pyrazoline structure. In solution in DMSO-d6 they are capable of exhibiting ring-chain equilibrium involving the 5-hydroxy-2-pyrazoline and enehydrazine tautomers. The latter form is represented by a mixture of Z- and E-isomers with a significant preponderance of the latter. The product from the reaction of 4-aminobenzohydrazide with 4-ethoxy-1,1,1-trifluorobut-3-en-2-one in a ratio of 1:2 has a structure containing 5-hydroxy-2-pyrazoline and enamine fragments.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1201–1206, August, 2014.
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Pakal’nis, V.V., Zerov, A.V., Yakimovich, S.I. et al. Ring-Chain Tautomerism of 3-Unsubstituted Trifluoromethyl-Containing n-Acyl-5-Hydroxy-2-Pyrazolines. Chem Heterocycl Comp 50, 1107–1112 (2014). https://doi.org/10.1007/s10593-014-1570-8
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DOI: https://doi.org/10.1007/s10593-014-1570-8