Synthesis and the reactions of trifluoromethylated 1,2,3-triketones 2-(het)arylhydrazones and 4,7-dihydroazolo[5,1-c]triazines

The coupling of trifluoromethylated 1,3-diketones with (het)aryldiazonium chlorides results mainly in the formation of 1,2,3-triketones 2-(het)arylhydrazones while using hetarylamine with a NH-group at the α-position of the heterocycle as the diazonium component gives 4,7-dihydroazolo[5,1-c]triazines due to cyclization at the trifluoroacetyl fragment. Trifluoromethylated 1,2,3-triketones 2-(het)arylhydrazones and 7-hydroxy-4,7-dihydroazolo[5,1-c]triazines react regio-selectively with methyl hydrazine and phenyl hydrazine to form 3-CF₃-pyrazoles. The long-range coupling constants (J_F-H) of 1-methylpyrazoles and the chemical shifts of trifluoromethyl groups in the ¹⁹F NMR spectra can be used for the determination of regio-isomeric structures of mono(trifluoromethyl)-substituted pyrazoles. 2-(Het)arylhydrazones and 4,7-dihydroazolo[5,1-c]triazines with two trifluoromethyl substituents afford the mixtures of cis- and trans-azopyrazoles in the reactions with hydrazines.     

Aliphatic aldehydes in the synthesis of carbo- and heterocycles. Part I. Synthesis of three-, four-, and five-membered rings

Data on the use of aliphatic aldehydes in the synthesis of three-, four-, and five-membered carbo- and heterocycles, published over the past 12 years, were summarized and systematized. Biological activity and synthetic utility of the resulting compounds was noted. The given data are classed according to the type of the ring formed.     

Competing processes in the condensation of diethyl ethoxymethylidenemalonate and malononitrile derivatives with CH acids containing a thiocarbamoyl group

Diethyl ethoxymethylidenemalonate and ethoxymethylidenemalononitrile react with CH acids containing a thiocarbamoyl group along several concurrent pathways to give both acyclic structures and pyridine and pyrimidine derivatives.     

N,N,N′-Trialkyl-1,8-diaminonaphthalenes: convenient method of preparation from protonated proton sponges and the first X-ray information

A simple procedure for the synthesis of N,N,N′-trialkyl-1,8-diaminonaphthalenes is described. It consists in partial demethylation (dealkylation) of commercially available proton sponge [1,8-bis(dimethylamino)naphthalene] and some of its derivatives at heating with HBr-KI-DMF system. Limitation, scope and a possible mechanistic pathway for the reaction are discussed. For isomeric 8-dimethylamino-1-methylamino- and 1-dimethylamino-8-methylamino-4-nitronaphthalenes, X-ray measurements have been conducted. The first examples of complete realkylation reactions in the naphthalene proton sponges are reported.     

Propanal in the Syntheses of Alkyl-substituted 3-Cyano-2-piperidone, 3-Cyano-2,5,6,7-tetrahydropyrindin-2(1H)-one, and 3-Cyanopyridine-2(1H)-thione

Condensation of propanal with cyanothioacetamide and morpholine gave 3-cyano-4-ethyl-5-methyl-6-morpholino-2-piperidone, the structure of which was studied by X-ray analysis. Reaction of propanal with cyanothioacetamides and cycloalkanone enamines gave 3-cyano-4-ethyl-2,5,6,7-tetrahydropyrindin-2(1H)-one and 3-cyano-4-ethyl-5,6-hexamethylenepyridine-2(1H)-thione. The latter was used for the preparation of substituted 2-benzyloxycarbonylmethylthiopyridine and 3-amino-2-benzyloxycarbonylthieno[2,3-b]pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1053–1059, July, 2005.     

Synthesis of Ammonium 5-Arylcarbamoyl-4-heteryl-6-methyl-3-cyano-1,4-dihydropyridine-2-thiolates and 4-Heteryl-5-carbamoyl-6-methyl-3-cyano-1,4-dihydropyridine-2-selenolates

The condensation of enamines derived from acetoacetanilides, heterocyclic aldehydes, and cyanothioacetamide yielded ammonium 5-arylcarbamoyl-5-heteryl-6-methyl-3-cyano-1,4-dihydropyridine-2-thiolates, which were subsequently used for the synthesis of substituted 2-alkylthio-1,4-dihydropyridines, 2-alkylthiopyridines, and thieno[2,3-b]pyridines. The reaction of acetoacetamide with heteroaromatic aldehydes and cyanoselenoacetamide in the presence of N-ethylmorpholine yielded N-ethylmorpholinium 4-heteryl-5-carbamoyl-6-methyl-3-cyano-1,4-dihydrolyridine-2-selenolates, from which substituted 2-alkylseleno-1,4-dihydropyridines were prepared.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 483–492.Original Russian Text Copyright © 2005 by Dyachenko.     

New method for the synthesis of 6-amino-4-aryl-3,5-dicyano-3,4-dihydropyridine-2(1H)-thiones by recyclization of 4-aryl-2,6-diamino-4H-thiopyranes

Ammonium 6-amino-4-aryl-3,5-dicyano-1,4-dihydropyridine-2-thiolates were synthesized by recyclization of 4-aryl-2,6-diamino-3,5-dicyano-4H-thiopyranes in the presence of organic bases. On acidification of the products, the corresponding substituted 3,4-dihydropyridine-2(1H)-thiones were obtained which were used in the synthesis of 2-alkylthio-1,4-dihydropyridines, bis-(pyridyl-2)disulfides and thieno[2,3-b]pyridines.Deceased.T. G. Shevchenko Lugansk State Pedagogical Institute, Lugansk 348011. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 909–914, July, 1997.     

A new method for the synthesis ofN-methylmorpholinium 4-aryl-5-cyano-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates and their properties

N-Methylmorpholinium 4-aryl-5-cyano-2-oxo-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates were obtained by the condensation of aromatic aldehydes, cyanothioacetamide, and Meldrum's acid in the presence ofN-methylmorpholine. They were then used in the syntheses of substituted 6-alkylthio-3,4-dihydropyridin-2(1H)-ones and 4,5-dihydrothieno[2,3-b]pyridin-6(7H)-ones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1852–1856, October, 1997.     

Total Nonnegativity of Infinite Hurwitz Matrices of Entire and Meromorphic Functions

In this paper we completely describe functions generating the infinite totally nonnegative Hurwitz matrices. In particular, we generalize the well-known result by Asner and Kemperman on the total nonnegativity of the Hurwitz matrices of real stable polynomials. An alternative criterion for entire functions to generate a Pólya frequency sequence is also obtained. The results are based on a connection between a factorization of totally nonnegative matrices of the Hurwitz type and the expansion of Stieltjes meromorphic functions into Stieltjes continued fractions (regular $C$ -fractions with positive coefficients).