A. N. Vasilenko

Reaction of 7-phenyl-7H-pyrazolo-[3,4-d][1,2,3]triazin-4-ol with thionyl chloride

The reaction of 7-phenyl-7H-pyrazolo[3,4-d][1,2,3]triazin-4-ol with thionyl chloride has been studied in the presence and absence of dimethyl formamide. It was found that heating the compound with thionyl chloride in the absence of dimethyl formamide gave 5-amino-1-phenyl-1H-pyrazole-4-carboxylic acid chloride and in its presence a mixture of 5-chloro-N-formyl-1-phenyl-1H-pyrazole-4-carboxamide, 5-chloro-1-phenyl-1H-pyrazole-4-carboxamide, and 4-chloro-6-(5-chloro-1-phenyl-1H-pyrazol-4-yl)-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine.

Conversions of 7-aryl-7H-pyrazolo[3,4-d]-[1,2,3]triazin-4-ols by the action of phosphorus pentoxide, pentasulfide, and oxychloride

The interaction of 7-aryl-7H-pyrazolo[3,4-d][1,2,3]triazin-4-ols with phosphorus pentoxide or pentasulfide leads to the formation of 6-(5-amino-1-aryl-1H-pyrazol-4-yl)-1-aryl-1H,4H-pyrazolo[3,4-d][1,3]oxazin-4-ones and 6-(5-amino-1-aryl-1H-pyrazol-4-yl)-1-aryl-1H,4H-pyrazolo[3,4-d][1,3]thiazine-4-thiones, respectively. Reaction with phosphorus oxychloride leads to 1-aryl-5-chloro-1H-pyrazole-4-carbonyl chlorides, from which the corresponding amides, hydrazides, and substituted 1,3,4-oxadiazoles were synthesized.

Reaction of 1-Aryl-1,3,4,4-tetrachloro-2-azabuta-1,3-dienes with aminoazoles

Reactions of polychlorinated 2-aza-1,3-dienes of the general formuls ArCCl=NCCl=CCl2 with 3(5)-aminopyrazoles, 3(5)-amino-1,2,4-triazoles, and 5-aminotetrazole led to the formation of substituted pyrazolo[1,5-a][1,3,5]triazines, [1,2,4]triazolo[1,5-a][1,3,5]triazines, and 2-azido-1,3,5-triazine derivatives whose structure was reliably established by spectral methods and X-ray analysis.

SYNTHESIS OF NOVEL PYRAZOLO(3,4-d)(1,2,3)TRIAZINES

Studies have been conducted of the reactions of 7-phenyl-3,7-dihydro-4H-pyrazolo[3,4-d]-[1,2,3]triazin-4-one with alkyl halides and formaldehyde, that occurred with retention of the pyrazolotriazine structure. Ethyl 2-(4-oxo-7-phenyl-4,7-dihydro-3H-pyrazolo[3,4-d][1,2,3]triazin-3-yl)-acetate was prepared by the reaction of 7-phenyl-3,7-dihydro-4H-pyrazolo[3,4-d][1,2,3]triazin-4-one with ethyl chloroacetate. It was used to synthesize the corresponding hydrazide with the aim of introducing the pyrazole or 1,3,4-oxadiazole fragments in the side chain of a bicyclic system.

Reaction of 2-aryl-4-dichloromethylidene-1,3-oxazol-5(4H)-ones with 2-aminopyridine

Reactions of multicenter electrophilic substrates, 2-aryl-4-dichloromethylidene-1,3-oxazol-5(4H)-ones, with 2-aminopyridine, involved cleavage of the dihydrooxazole ring by the primary amino group of nucleophilic reagent and subsequent cyclization to imidazopyridine derivatives. The latter reacted with morpholine and its analogs via recyclization with formation of 5-amino-2-aryl-N-(pyridin-2-yl)-1,3-oxazole-4-carboxamides.

Synthesis and transformations of derivatives of 2-aryl-5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carboxylic acid

On the basis of methyl esters of 2-aryl-5-hydrazino-1,3-oxazole-4-carboxylic acids the earlier unknown methyl esters of 2-aryl-5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carboxylic acids as well as their functional derivatives were synthesized. The latter were used for further transformations, in particular, for introducing the residues of highly basic aliphatic amines into the 5 position of oxazole, and the oxazol-2-yl moiety into the 4 position of the oxazole ring.

Synthesis of new 2,5-diamino-1,3-thiazole and 2-thiohydantoin derivatives by condensation of N-(2-Aryl-1-chloro-2-oxoethyl) carboxamides with thioureas

N-(2-Aryl-1-chloro-2-oxoethyl) carboxamides react under mild conditions with thiourea, N-alkyl-and N-arylthioureas, and various N,N′-disubstituted thioureas, following the Hantzsch reaction scheme. The reactions are selective, and the resulting 2,5-diamino-1,3-thiazole derivatives undergo recyclization acid followed by hydrolysis to give substituted 2-thiohydantoins on heating with hydrochloric acid in ethanol.

Synthesis of 3-amino-1-benzyl-4-benzenesulfonyl-2-carbonitrilo-1H-pyrrole and preparation of related pyrrolo[3,2-d]pyrimidines

A method for the synthesis of a new 4-phenylsulfonyl-substituted 3-aminopyrrole was developed and related pyrrolo[3,2-d]pyrimidine derivatives were synthesized.

Transformation of substituted 5-amino-1,3-oxazole-4-carbonitriles into new 3,4,5-triaminopyrazole derivatives

Reactions of accessible 5-alkylamino- and 5-arylamino-1,3-oxazole-4-carbonitriles with hydrazine hydrate on heating involved a complex transformation sequence resulting in the formation of 3,4,5-triaminopyrazole derivatives. The structure of the products was confirmed by their cyclocondensation with acetylacetone, leading to 2-alkyl(aryl)amino-3-acylamino-5,7-dimethylpyrazolo[1,5-a]pyrimidines which were identified by NMR spectroscopy using COSY, NOESY, HMQC, and HMBC techniques.

Reactions of N-(1-chloro-2-oxo-2-phenylethyl) carboxamides with thiosemicarbazide and its derivatives

N-(1-Chloro-2-oxo-2-phenylethyl)acet-, -benz-, and -4-methylbenzamides reacted with thiosemicarbazides and aromatic aldehyde thiosemicarbazones to give derivatives of 5-amino-2-hydrazino-1,3-thiazole. The latter underwent recyclization and acid hydrolysis on heating with hydrochloric acid to produce substituted 3-amino-2-thiohydantoins.