Polymerizable tautomers. VI. Solvent effects on polymerization and copolymerization of ethyl 4-methyl-3-oxo-4-pentenoate

The radical polymerization of ethyl 4-methyl-3-oxo-4-pentenoate (EMAA) was investigated at 60°C in benzene and acetonitrile. In both solvents, the kinetic results disagreed with the conventional model of radical polymerization. A remarkable solvent effect on monomer reactivity ratio was observed for the copolymerization of EMAA and styrene. Regression analysis of the monomer reactivity ratio with the solvatochromic parameters gives a good linear relationship, taking into account polarity and hydrogen-bond donating acidity of the solvent as the major factors.     

4-hydroxy-2-quinolones. 43. Thermolysis of ethyl esters of 1-R-2-oxo-4-hydroxy-quinoline-3-carboxylic acids

Ethyl esters of 1-R-2-oxo-4-hydroxyquinoline-3-carboxylic acids under thermolysis conditions are converted to 5,9-di-R-6,7,8-trioxodiquinolino[3,4-b;3,4-e]-4H-pyrans. One of the synthesized compounds was studied by X-ray diffraction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 516–522, April, 2000.     

4-hydroxy-2-quinolones. 41. Reaction of hydrazides of 1-R-2-oxo-4-hydroxyquinoline-3-carboxylic acids with ethyl orthoformate

The boiling of hydrazides of 1-R-2-oxo-4-hydroxyquinoline-3-carboxylic acids in an excess of ethyl orthoformate leads to the formation of ethyl esters of the corresponding quinoline-3-carboxylic acids, the structure of which was confirmed by X-ray diffraction analysis.For the Communication 40, see [1].National Pharmaceutical Academy of Ukraine, Kharkov 310002. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 207–211, February, 2000.     

4-Hydroxy-2-quinolones 119. Reaction of ethyl 1-R-4-chloro-2-oxo-1,2-dihydroquinoline-3-carboxylate with malononitrile

In acid medium ethyl 1-R-4-dicyanomethyl-2-oxo-1,2-dihydroquinoline-3-carboxylates are hydrated in the ketenimine tautomer form exclusively to the corresponding quinolylcyanoacetamides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 856–863, June, 2007.     

4-Hydroxy-2-quinolones 120. Synthesis and structure of ethyl 2-hydroxy-4-oxo-4H-pyrido-[1,2-a]pyrimidine-3-carboxylate

An improved method for the preparation and purification of ethyl 2-hydroxy-4-oxo-4H-pyrido[1,2-a]-pyrimidine-3-carboxylates is proposed. According to ¹H and ¹³C NMR spectroscopic data the synthesized compounds exist in DMSO solution in the 2-hydroxy-4-oxo form while in the crystal (at least for the case of the unsubstituted derivative) X-ray analysis shows that it occurs in the bipolar 2,4-dioxo form. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 864–876, June, 2007.     

4-hydroxy-2-quinolones. 109. Alkylation of 4-substituted ethyl 2-oxo-1,2-dihydro-quinoline-3-carboxylates

The alkylation of the ethyl esters of 4-methyl, 4-chloro-, and 4-amino substituted 2-oxo-1,2-dihydroquinoline-3-carboxylic acid by ethyl iodide in the system DMF/K₂CO₃ has been studied. Features of the structure of the starting compounds and their effect on the ratio of the N-and O-alkyl products formed are discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1502–1507, October, 2006.     

Highly enantioselective sequential hydrogenation of ethyl 2-oxo-4-arylbut-3-enoate to ethyl 2-hydroxy-4-arylbutyrate

The hydrogenation of (E)-ethyl 2-oxo-4-arylbut-3-enoate with [NH2Me2](+)[{RuCl [(S)-SunPhos]}2(mu-Cl3)] gave ethyl 2-hydroxy-4-arylbutyrate with 94-96% ee. Further investigation has proved that the hydrogenation proceeded via a sequential hydrogenation of CO and CC bonds, which is sensitive to the reaction temperature. Hydrolysis of ethyl 2-hydroxy-4-phenylbutyrate (ee 93%) provided the 2-hydroxy-4-phenylbutyric acid with 81% yield at 99% ee after a single recrystallization from 1,2-dichloroethylene.     

4-Hydroxy-2-quinolones 130. The reactivity of ethyl 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylates

The high reactivity of ethyl 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxylates is governed by the simultaneous presence of the 4-OH and 2-C=O groups in the pyridine part of the molecule. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1503–1508, October, 2007.     

Synthesis and antibacterial activity of ethyl 2-amino-6-methyl-5-oxo- 4-aryl-5,6-dihydro-4H-pyrano[3,2-c]quinoline-3-carboxylate

The three-component reaction of 4-hydroxy-1-methyl-2(1H)-quinolinone, aromatic aldehydes and ethyl cyanoacetate was carried out in the presence of a catalytic amount of 4-dimethyl aminopyridine(DMAP) in aqueous ethanol. The reactions result in the formation of pyranoquinoline derivatives in excellent yields. Antibacterial activity has been evaluated against Gram positive and Gram negative bacteria for some of the synthesized compounds. The results indicated that these compounds are moderately effective against bacterial growth and their effectiveness is highest against Pseudomonas aeruginosa.     

Reaction of 2-substituted 4-oxo-5, 6-benzo-1, 3, 2-dioxaphosphorinanes with ethyl pyruvate

The reaction of 2-substituted 4-oxo-5, 6-benzo-1, 3, 2-dioxaphosphorinanes with ethyl pyruvate affords ring-expansion products, i.e., diastereomeric 2-substituted 2, 5-dioxo-6, 7benzo-1, 3, 2-dioxaphosphepanes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 565–567, March, 1993.The authors are grateful to Ye.I.Gol'dfarb for recording the 31_P-(1_H) NMR spectra.     

Features of reactions of polyfluorinated ethyl 4-oxo-2-pnenyl-4H-chromene-3-carboxylates with N-nucleophiles

Ethyl 5,6,7,8-tetrafluoro-4-oxo-2-phenyl-4H-chromene-3-carboxylate in reactions with primary amines is characterized by a chromone-coumarin rearrangement affording 3-[amino(phenyl)methylene]-6,7,8-trifluoro-2H-chromene-2,4(3H)-diones, and ethyl 4-oxo-2-phenyl-5,6,7,8-tetrafluoro-4H-chromene-3-carboxylate characteristically adds the amine at the C² site of the flavone furnishing 3-amino-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylates which depending on the substituent at the amino group are capable of intramolecular cyclization into 3-[(alkylamino)(phenyl)methylene]-5,6,7,8-tetrafluoro-2H-chromene-2,4(3H)-dione or in the case of benzylamine substituent, into ethyl 1-benzyl-5-hydroxy-4-oxo-2-phenyl-6,7,8-trifluoro-1,4-dihydroquinoline-3-carboxylate. The main process in the reaction of tri- and tetrafluoroflavones with secondary amine (1-methylpiperazine) is the nucleophilic substitution at the C⁷ of flavone. In the reaction with 1,2-phenylenediamine 3-[(2-aminophenyl)amino]-3-phenyl-2-(2,3,4,5-tetrafluoro-6-hydroxybenzoyl)acrylate was obtained from tetrafluoroflavone and 1H-benzimidazol-2-yl(3,4,5-trifluoro-2-hydroxyphenyl)methanone, from trifluoroflavone.     

Electrochemical oxidation of ethyl 3-oxo-3-phenyl-2-phenylhydrazonopropionate

The electrochemical oxidation of ethyl 3-oxo-3-phenyl-2-phenylhydrazonopropionate has been studied in the pH range 3.0–11.0 at a pyrolytic graphite electrode by linear and cyclic sweep voltammetry, coulometry and spectral studies. The results indicate that the 2 e⁻, 2 H⁺ oxidation of this compound gives phenol and ethyl 3-phenyl-2,3-dioxopropionate as the major products of electrooxidation.     

4-hydroxy-2-quinolones. 96. Synthesis and properties of 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acid

Alkaline hydrolysis of the ethyl ester of 4-(cyanoethoxycarbonylmethyl)-2-oxo-1,2-dihydroquinoline-3-carboxylic acid is accompanied by decarboxylation with loss of two molecules of CO₂ and leads to 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acid. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 887–893, June, 2006.     

Synthesis and crystal structure of ethyl 1-benzyl-2-hydroxy-5-methyl-3-oxo-2-phenacyl-2,3-dihydropyrrole-4-carboxylate

Reaction of 5-phenyl-2,3-dihydro-2,3-furandione with ethyl 3-benzylamino-2-butenoate, resulting in ethyl 1-benzyl-2-hydroxy-5-methyl-3-oxo-2-phenacyl-2,3-dihydropyrrole-4-carboxylate and benzylamide ofN-benzoylpyruvic acid, was studied. The structure of the pyrrole derivative was confirmed by X-ray analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1552–1555, August, 1995.     

4-hydroxy-2-quinolones. 94. Improved synthesis and structure of 1-hydroxy-3-oxo-5,6-dihydro-3h-pyrrolo[3,2,1-i,j]-quinoline-2-carboxylic acid ethyl ester

A modified method is proposed for preparation and purification, and the special features of the spatial structure have been studied for the ethyl ester of 1-hydroxy-3-oxo-5,6-dihydro-3H-pyrrolo[3,2,1-i,j]-quinoline-2-carboxylic acid. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 718–723, May, 2006.     

4-Hydroxy-2-quinolones. 111. Simple synthesis of 1-substituted 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acids

A preparative method of obtaining 1-substituted 4-methyl-2-oxo-1,2-dihydroquinoline-3-carboxylic acids is proposed. Features of their spatial structure have been studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 69–74, January, 2007.     

Efficient synthesis of 2,6-disubstituted-5-hydroxy-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid ethyl esters

A general procedure is described for the preparation of 6-substituted-5-hydroxy-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid ethyl esters (6-substituted-5-hydroxy-3(2H)-pyridazinone-4-carboxylic acid ethyl esters). These compounds are shown to undergo selective alkylation at the 2-position in moderate to good yields (19-77%) to afford 2,6-disubstituted-5-hydroxy-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid ethyl esters (2,6-disubstituted-5-hydroxy-3(2H)-pyridazinone-4-carboxylic acid ethyl esters).