Reactions of Acylpyruvic Acids and 2,3-Dihydrofuran-2,3-diones with 2,3-Diaminopyridine

Acylpyruvic acids readily react with 2,3-diaminopyridine to form (Z)-3-acylmethylene-1H-3,4-di- hydropyrido[2,3-b]pyrazin-2-ones. 5-Aryl-2,3-dihydrofuran-2,3-diones which can be regarded as lactones derived from -enolized aroylpyruvic acids react with 2,3-diaminopyridine under mild conditions, yielding regioisomeric (Z)-2-aroylmethylene-4H-1,2-dihydropyrido[2,3-b]pyrazin-3-ones. The structure of the products and reaction chemoselectivity are discussed.     

Chemistry of 2-methylene-2,3-dihydro-3-pyranones

5-Aryl-2-acylmethylene-2,3-dihydro-3-furanones are recyclized by the action of hydrazine hydrate with the formation of 3-substituted 6-aryl-1H-4-pyridazinones, 3-alkoxycarbonylacetyl-5-aryl-4-methylpyrazoles, or 5-aryl-3-(3-oxo-2,3-dihydro-1H-5-pyrazolyl) pyrazoles, depending on the structure of the starting materials and the ratio of the reactants. The last-named are also obtained by the hydrazinolysis of the known 2-alkoxycarbonylmethyl-2-hydroxy-1,5-diaryl-2,3-dihydro-3-pyrrolones.For Communication 6, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1031–1038, August, 1992.     

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...     

Acylpyruvic Acids Amides and Hydrazides: VIII. Synthesis of Pivaloylpyruvamides and Their Reactions with Benzylamine and Arylamines

Pivaloylpyruvamides were obtained by reaction of pivaloylpyruvic acid with ammonia, primary and secondary amines. The amides in solutions exist as an equilibrium tautomeric mixture of ketoenol and minor -diketone forms. The pivaloylpyruvamides under mild conditions react with benzylamine or arylamines to furnish products of substitution at the -carbonyl group, the corresponding amides of (Z)-2-benzylamino- or 2-arylamino-5,5-dimethyl-4-oxo-2-hexenoic acid. The latter also exist in solutions as two tautomers. The amides synthesized possess a biological activity.     

Synthesis and Biological Activity of Mono- and Dibromo Derivatives of 2-Amino-5-(2-aryl-2-oxoethylidene)-4-oxo-1<Emphasis Type="Italic">H</Emphasis>-4,5-dihydrofuran-3-carboxylic Acids

The previously unknown mono- and dibromo derivatives of 2-amino-5-(2-aryl-2-oxo-ethylidene)-4-oxo-1H-4,5-dihydrofuran-3-carboxylic acids were synthesized. Antinociceptive and antimicrobial activity of the obtained compounds was studied.     

Reactions of Ethyl 2-Amino-5-(2-aryl-2-oxoethylidene)- 4-oxo-4,5-dihydrofuran-3-carboxylates and 2-Amino-5-(2-aryl- 2-oxoethylidene)-4-oxo-4,5-dihydrofuran-3-carbonitriles with Alcohols

Ethyl 2-amino-5-(2-aryl-2-oxoethylidene)-4-oxo-1H-4,5-dihydrofuran-3-carboxylates and 2-amino- 5-(2-aryl-2-oxoethylidene)-4-oxo-1H-4,5-dihydrofuran-3-carbonitriles reacted with alcohols in the presence of a catalytic amount of concentrated aqueous HCl to give the corresponding 5-alkoxy-2-amino-5-(2-aryl-2- oxoethyl)-4-oxo-1H-4,5-dihydrofuran-3-carboxylic acid derivatives. A probable reaction mechanism was proposed on the basis B3LYP/6-311G(d) quantum chemical calculations.     

Chemistry of iminofurans: XIII. Recyclization of 4-arylamino-2-<Emphasis Type="Italic">tert</Emphasis>-butyl-5-oxo-2,5-dihydrofuran-2-yl acetates with ethyl cyanoacetate

Recyclization of 4-arylamino-2-tert-butyl-5-oxo-2,5-dihydrofuran-2-yl acetates with ethyl cyanoacetate in the presence of triethylamine afforded the corresponding ethyl 2-amino-1-aryl-5-(3,3-dimethyl-2-oxobutylidene)-4-oxo-1H-4,5-dihydropyrrole-3-carboxylates.