Synthesis and Intramolecular Cyclization of N-Substituted 2-Amino-4-aryl-4-oxo-2-butenoic Acids

Treating 4-aryl-2,4-dioxobutanoic acids with aromatic amines, 4-aminoantipyrine, and benzophenone hydrazone furnished N-substituted 2-amino-4-aryl-4-oxo-2-butenoic acids that existed in solutions in enaminoketone and iminoketone forms. The acids obtained underwent in the presence of acetic anhydride cyclization into N-substituted 5-aryl-3-imino-3H-furan-2-ones.     

Polarographic behavior of 4-aryl-2-(1,2-diphenyl-2-oxoethylidenehydrazino)-4-oxo-2-butenoic acids

Polarographic reduction of 4-aryl-2-(1,2-diphenyl-2-oxoethylidenehydrazino)-4-oxo-2-butenoic acids in 2-propanol-water solutions proceeds with the formation of two or three irreversible cathode waves and leads to 4-aryl-2-(1,2-diphenyl-2-hydroxyethylhydrazino)-4-hydroxybutanoic acids. The latter suffer hydrolysis with the rupture of the C²-NH bond and the formation of 4-aryl-2,4-dihydroxybutanoic acids.     

Synthesis and transformations of 2- and 4-(2-Methylquinolin-4-ylamino)benzoic acids and ethyl 4-(2-methylquinolin-4-ylamino)benzoates and their fluorescent properties

2- and 4-(2-Methylquinolin-4-ylamino)benzoic acids and ethyl 4-(2-methylquinolin-4-ylamino)-benzoates having a substituent in the 6(8)-position of the quinoline ring were synthesized by reaction of the corresponding substituted 4-chloro-2-methylquinolines with 2- and 4-aminobenzoic acids and ethyl 4-aminobenzoate. Intramolecular cyclization of 2-(2-methylquinolin-4-ylamino)benzoic acids in concentrated sulfuric acid gave 7-hydroxy-6-methyldibenzo[b,h][1,6]naphthyridines, and ethyl 4-(2-methylquinolin-4-ylamino)benzoates were converted into 4-(2-methylquinolin-4-ylamino)benzoic acids by alkaline hydrolysis.     

Iminofuran chemistry: VII. Intramolecular cyclization of 2-N-aryl-substituted derivatives of 2-amino-4-aryl-4-oxobut-2-enoic and 2-amino-5,5-dimethyl4-oxohex-2-enoic acids

The cyclization at the treatment of acetic anhydride of 4-aryl-2-arylamino-4-oxobut-2-enoic and 2-arylamino-5,5-dimethyl-4-oxohex-2-enoic acids was investigated furnishing derivatives of 5-aryl-3-aryl-imino-3H-furan-2-ones and 4-arylamino-2-tert-butyl-2,5-dihydro-5-oxofuran-2-yl acetate respectively. 2-N²-Methylenesubstituted 4-aryl-2-hydrazino-4-oxobut-2-enoic and 5,5-dimethyl-2-hydrazino-4-oxohex-2-enoic acids cleanly underwent cyclization under the effect of acetic anhydride into 5-aryl-3-hydrazono-3H-furan-2-ones and 5-tert-butyl-3-hydrazono-3H-furan-2-ones.     

Highly enantioselective hydrogenation of 2-oxo-4-arybutanoic acids to 2-hydroxy-4-arylbutanoic acids

The Ru-catalyzed asymmetric hydrogenation of 2-oxo-4-arybutanoic acids to afford 2-hydroxy-4-arybutanoic acids was accomplished by employing SunPhos as chiral ligand and 1 M aq HBr as additive. The high enantioselectivities (88.4%-92.6% ee) and efficiency (TON=10,000, TOF=300 h⁻¹) make this method efficient for the synthesis of an important intermediate, (R)-2-hydroxy-4-phenylbutanoic acid, for ACE inhibitors.     

Synthesis of 4-aryl-2-hydroxy-4-oxo-2-butenoic (Aroylpyruvic) acids N-(4-Acetylaminosulfonylphenyl)amides

Methyl aroylpyruvates react with sodium 4-aminobenzenesulfonylacetamide in acetic acid to afford 4-aryl-2-hydroxy-4-oxo-2-butenoic acids N-(4-acetylaminosulfonylphenyl)amides. The latter were studied in reactions with hydrazine hydrate.     

Synthesis of Derivatives of (4-Methyl-2-Quinolylthio)acetic and (4-Methyl-2-Quinolylthio)propionic Acids

An efficient synthesis has been developed for derivatives of (4-methyl-2-quinolylthio)acetic and (4-methyl-2-quinolylthio)propionic acids by the reaction of 4-methyl-2-thioxoquinoline with methyl methacrylate, the amide of methacrylic acid, acrylonitrile, ethyl bromoacetate, and ethyl acrylate. The hydrolysis of the resultant intermediates by (quinolylthio)acetic and (quinolylthio)propionic acids gave the corresponding acid products, which are also formed in the reaction of 4-methyl-2-thioxoquinoline with chloroacetic and acrylic acids. The reaction of 4-methyl-2-thioxoquinoline with allyl bromide was studied. The potassium permanganate oxidation of the resultant 2-allylthio-4-methylquinoline led to (4-methyl-2-quinolylthio)acetic acid.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 403–406, April, 2005.     

Chemistry of iminofurans: V. Synthesis,structure, and cyclization of 4-R-4-oxo-2-[2-(2-oxo-1,2-diphenylethylidene)hydrazino]but-2-enoic acids

Reactions of 1,2-diphenylethane-1,2-dione hydrazone with 4-aryl-2-hydroxy-4-oxobut-2-enoic and 2-hydroxy-5,5-dimethyl-4-oxohex-2-enoic acids provided 4-aryl-4-oxo-2-[2-(2-oxo-1,2-diphenylethylidene) hydrazino]but-2-enoic and 5,5-dimethyl-4-oxo-2-[2-(2-oxo-1,2-diphenylethylidene)hydrazino]hex-2-enoic acids. The acids derivatives can exist in solutions as Z- and β-enehydrazino-or β-ketohydrazone forms, and under the treatment with acetic anhydride they undergo cyclization into 5-aryl- and 5-tert-butyl-3-[2-(2-oxo-1,2-diphenylethylidene)hydrazono]-2,3-furandiones.     

2-Trifluoromethyl-4-butanolides

Specific features were elucidated for the intramolecular cyclization of 2-trifluoromethyl-4-pentenoic acids (Ia)-(Ic) under acid catalysis and upon bromination and epoxidation of the double bond. Feasibility was demonstrated for the lactonization of acids (Ia)-(Ic) upon the trifluoroacetoxylation of the double bond and some properties of the butanolide products were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 516–521, February, 1991.     

Synthesis of methyl -substituted 4-amino methyl-4-butanolides and 5 -hydroxy-2-piperidones

Esters of 5-amino-4-hydroxy-3-methylvaleric acids, which exist as pairs of diastereomers and are readily converted to the corresponding methyl-substituted 4-aminomethyl-4-butanolides or 5-hydroxy-2-piperidones, are obtained by reaction of esters of 3-methyl-4, 5-epoxy-2-pentenoic acid with amines and subsequent hydrogenation of the resulting esters of 5-amino-4-hydroxy-3-methyl-2-pentenoic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 594–598, May, 1975.     

Some reactions of 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido) acetic acids

In situ generated 2,4-diaryl substituted münchnones from 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido)acetic acids react with acetic anhydride in the presence of 2-nitromethylene thiazolidine, which is most likely acting as a base, and unexpectedly undergo a Dakin–West type reaction and a concurrent autoxidation reaction leading to the formation of (E)-1-(N,4-dimethylbenzamido)-1-(4-fluorophenyl)prop-1-en-2-yl acetate, 4-substitutedphenyl-N-methyl-N-(4-substitutedbenzoyl) benzamides and p-substituted benzoic acids. In addition, a novel and efficient access to N-acyl urea derivatives is described by the reaction between 2-(4-substitutedphenyl)-2-(N-methyl-N-4-substitutedbenzamido)acetic acids and cyclohexyl, isopropyl carbodiimides in the presence of a base. The structures of all new products were identified on the basis of NMR and IR spectra, along with X-ray diffraction data and HRMS measurements.     

Iminofurans chemistry: IV. Synthesis and structure of 2-<Emphasis Type="Italic">N</Emphasis>-aryl-substituted derivatives of 2-amino-4-aryl-4-oxobut-2-enoic and 2-amino-5,5-dimethyl-4-oxohex-2-enoic acids

Reactions of arylamines with 4-aryl-2-hydroxy-4-oxobut-2-enoic and 2-hydroxy-5,5-dimethyl-4-oxohex-2-enoic acids gave rise to 4-aryl-2-arylamino-4-oxobut-2-enoic and 2-aryl-amino-5,5-dimethyl-4-oxohex-2-enoic acids that existed in solutions as Z- and E-isomers or in a ring form as 3-arylamino-5-tert-butyl-5-hydroxyfuran-2(5H)-ones. The probable cyclization mechanism of these compounds into 5-R-3-arylimino-3H-furan-2-one derivatives was considered.     

Regiospecific alkylation of tetronic acids : Formation of 4-alkoxy-5H-furan-2-ones and 2-alkoxy-5H-furan-4-ones

2-Alkoxy-5$\text{H}$-furan-4-ones (7,8) and 4-alkoxy-5$\text{H}$-furan-2-ones (4,5) were prepared regiospecifically and in high yields from tetronic acids (4-hydroxy-5$\text{H}$-furan-2-ones) (2) in the first case by acetylating the 4-OH group and then reacting with trialkyloxonium tetrafluoroborate, and in the second case by alkylating tetrabutylammonium tetronates with dialkyl sulfate, respectively. Direct alkylation of tetronic acids with trialkyloxonium tetrafluoroborate gave in four cases regiospecific 2-O-alkylation, in one case 4-O-alkylation and in two other cases mixtures of 2- and 4-alkoxy derivatives.     

4-aryl-2-hydroxy-4-oxobut-2-enoic acids <Emphasis Type="Italic">N</Emphasis>-(2-pyridyl)amides in reactions with diazo compounds

Reactions of 4-aryl-2-hydroxy-4-oxobut-2-enoic acids N-(2-pyridyl)amides with diazomethane, diazoethane, diaryldiazomethanes, and diazofluorene lead to the formation of 2-alkoxy-4-aryl-4-oxobut-2-enoic acids N-(2-pyridyl)amides, 3-aroyl-5-methylpyrazole-4-carboxylic acids N-(2-pyridyl)amides, and 3-alkoxy-3-(2-aryl-2-oxoethyl)-2,3-dihydro-2-oxoimidazo[1,2-a]pyridines. The composition and structure of compounds obtained depend on the nucleophilic nature of the diazo compound and on the character of substituents in the aryl and pyridine parts of the substrate.     

4-Hydroxy-2-quinolones. 97. Simple synthesis of the esters of 4-halo-substituted 2-oxo-1,2-dihydroquinoline-3-carboxylic acids

Short term treatment of 3-ethoxycarbonyl-4-morpholino-2-oxo-1,2-dihydroquinoline with aqueous solutions of hydrohalogen acids leads to the formation of the ethyl esters of 4-halo-substituted 2-oxo-1,2-dihydroquinoline-3-carboxylic acids. Hydrolysis in HF is possible on extended boiling only to the 4-hydroxy derivative. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1022–1025, July, 2006.     

Acetylenic Hydroperoxides Derived from 2e-Methyldecahydroquinolin-4-one

2e-Methyldecahydroquinolin-4-one was reacted with lithium tert-alkylperoxy acetylides to prepare 4-hydroxy-2e-methyl-4-(2-methyl-2-tert-alkylperoxy-1-butyn-4-yl)decahydroquinolines. The latter readily react with carboxylic acids and methyl iodide, affording the corresponding salts.     

4-Hydroxyquinol-2-ones. 85. Synthesis of 2-Chloro-4-hydroxyquinoline-3-carboxylic Acid Ethyl Ester

The behavior of 2-chloro-4-hydroxy- and 4-chloro-2-oxoquinoline-3-carboxylic acids under acid catalyzed esterification conditions with methanol has been studied. A method is proposed for obtaining 2-chloro-4-hydroxyquinoline-3-carboxylic acid ethyl ester. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1195–1197, August, 2005.     

Synthesis,Intramolecular Cyclization,and Antinociceptive Activity of Substituted 2-[2-(4-Nitrobenzoyl)hydrazinylidene]-4-oxobut-2-enoic Acids

Russian Journal of Organic Chemistry - New substituted 2-[2-(4-nitrobenzoyl)hydrazinylidene]-4-oxobut-2-enoic acids have been synthe­sized by condensation of 4-nitrobenzohydrazide with...     

Synthesis of 2-aryl-2-trifluoromethyl-1,3-thiazolidin-4-ones and 2-aryl-2-trifluoromethyltetrahydro-4<Emphasis Type="Italic">H</Emphasis>-1,3-thiazin-4-ones and their oxidation with hydrogen peroxide

Reactions of aryl trifluoromethyl ketone imines with 2-sulfanylacetic and 3-sulfanylpropanoic acids afforded 2-aryl-2-trifluoromethyl-1,3-thiazolidin-4-ones and 2-aryl-2-trifluoromethyltetrahydro-4H-1,3-thiazin-4-ones, respectively. Their subsequent oxidation with hydrogen peroxide gave the corresponding 2-aryl-2-trifluoromethyl-1,3-thiazolidin-4-one 1-oxides and 2-aryl-2-trifluoromethyltetrahydro-4H-1,3-thiazin-4-one 1-oxides and 1,1-dioxides.     

Chemistry of iminofurans: VI.* Synthesis and structure of 2-(2-ylidenehydrazino)-substituted 4-aryl-4-oxobut-2-enoic and 5,5-dimethyl-4-oxohex-2-enoic acids

Hydrazones derived from substituted benzophenones and fluorenone reacted with 4-aryl-2-hydroxy-4-oxobut-2-enoic and 2-hydroxy-5,5-dimethyl-4-oxohex-2-enoic acids to give the corresponding 2-(2-ylidenehydrazino) derivatives which may be used as initial compounds for the synthesis of 3-hydrazono-3H-furan-2-ones. The obtained but-2-enoic and hex-2-enoic acid derivatives in solution may exist as Z- and E-isomeric enehydrazine tautomers or hydrazone tautomers with syn or anti orientation of substituents with respect to the double C=N bond.