Regioselective cyclocondensation of ethyl 2-ethoxymethylidene-3-oxo-3-polyfluoroalkylpropionates with thiazolylhydrazines

Ethyl 2-ethoxymethylidene-3-oxo-3-polyfluoroalkylpropionates reacted in a regioselective fashion with thiazolylhydrazines to give the corresponding ethyl 1-thiazolyl-5-fluoroalkyl-1H-pyrazole-4-carboxylates. The product structure was determined on the basis of NMR and X-ray diffraction data.     

New fluorine-containing polyazaheterocycles

Interaction of perfluoropentene-2 with ethylenediamine, diethylenetriamine, and triethylenetetramine forms previously unknown fluorine-containing azaheterocycles in yields of 25–74%. The structure of the compounds obtained has been confirmed by¹H and¹⁹F NMR methods and mass spectrometry.Department of Fine Organic Synthesis, Institute of Organic Chemistry, Urals Branch, Russian Academy of Sciences, 620219 Ekaterinburg. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2170–2174, September, 1992.     

Hydrolytic Stability and Photostability of Boron Complexes of Dibenzoylmethane with Various Substituents at the Boron Atom

High Energy Chemistry - The basic photophysical characteristics and the hydrolytic stability and photostability of dibenzoylmethanatoboron complexes containing various substituents at the boron...     

Features of synthesis and structure of ethyl (2<Emphasis Type="Italic">Z</Emphasis>)-3-hydroxy-(2,3,4,5-tetrafluorophenyl)-propyl-2-enoate

The structure of key intermediates in the synthesis of fluoroquinolone antibiotics: diethyl (2,3,4,5-tetrafluorobenzoyl)malonate and ethyl (2Z)-3-hydroxy-(2,3,4,5-tetrafluorophenyl)prop-2-enoate was for first time studied using X-ray diffraction (XRD) and ¹H, ¹⁹F NMR spectroscopy. In solution both the esters were shown to exist as a mixture of enol and ketone tautomeric forms with predominance of the latter. According to the XRD analysis, ethyl (2Z)-3-hydroxy-(2,3,4,5-tetrafluorophenyl)prop-2-enoate in the solid state exists entirely in the enol form.     

Synthesis and structure of 4-hydroxy-4-fluoroalkyl-1,4-dihydroimidazo[5,1-<Emphasis Type="Italic">c</Emphasis>][1,2,4]triazines

Azo coupling of fluorinated 1,3-diketones with 4-ethoxycarbonyl-1H-imidazole-5-diazonium chloride led to the formation of 4-hydroxy-4-polyfluoroalkyl-1,4-dihydroimidazo[5,1-c][1,2,4]triazines. According to the ¹H and ¹⁹F NMR data, these compounds in solution give rise to ring-chain tautomerism via opening of the C⁴-N⁵ bond, which is especially characteristic of dihydroimidazotriazines with a polyfluoroalkyl substituent longer than trifluoromethyl group.     

Reactions of ethyl 5,6,7,8-tetrafluoro-2-methylchromone-3-carboxylate and 3-acetimidoyl-5,6,7,8-tetrafluoro-4-hydroxycoumarin with S-nucleophiles

The reactions of ethyl 5,6,7,8-tetrafluoro-2-methylchromone-3-carboxylate with mercaptoacetic acid and 1,2-ethanedithiol afforded C(7)-substitution products. The above-mentioned chromone reacted with 2-mercaptoethanol to yield 7-mono- or 5,7,8-trisubstituted products depending on the reaction conditions. The reaction of 3-acetimidoyl-5,6,7,8-tetrafluoro-4-hydroxycoumarin with 2-mercaptoethanol afforded a 5,7,8-trisubstituted produect. The acyl-lactone rearrangement of mono- and trisubstituted chromones yielded the corresponding coumarins. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1557–1561, August, 1999.