O. V. Shablykin

Synthesis of 4-alkyl-2-aryl-1,3-oxazole[5,4-d]pyrimidine-7(4H)-thiones and 6-alkyl-2-aryl-1,3-oxazole[5,4-d]pyrimidin-7(6H)-ones from 2-aroylamino-3,3-dichloroacrylonitriles

The sequential treatment of accessible 2-aroylamino-3,3-dichloroacrylonitriles with excess of amine, triethyl orthoformate, and hydrogen sulfide results in 4-substituted oxazole[5,4-d]pyrimidine-7(4H)-thione. The sequential reactions of the same reagents with sodium methylate, trifluoroacetic acid, triethyl orthoformate, and amines give rise to the 6-substituted oxazole[5,4-d]pyrimidin-7(4H)-one.

New transformations of 5-Hydrazino-2-phenyl-1,3-oxazole-4-carbonitrile

Treatment of 5-hydrazino-2-phenyl-1,3-oxazole-4-carbonitrile with acetylacetone lead to the formation of a substituted pyrazole residue on C5, which enhanced the electrophilicity of the cyano group in position 4 so that it became capable of reacting with hydrogen sulfide, sodium azide, and hydroxylamine. As a result, the corresponding azole fragments were introduced into position 4 of the 5-(1H-pyrazol-1-yl)-1,3-oxazole system.

Synthesis of 2-aryl-6H,7H-[1,3]oxazolo[5,4-d]pyrimidine-7-thione and 2-aryl-6H,7H-[1,3]thiazolo[5,4-d]pyrimidine-7-thione using 2-aroylaminomalonodiamide

There are two strategic approaches to construct the azolopyrimidine system: via cyclization of the pyrimidine ring on an azole or by fusion of azole ring with the pyrimidine. In this work we used two approaches using 2-aroylaminomalonodiamides Ia–Ic as the starting materials [5]. In this case, the target products were 2-aryl-6H,7H-[1,3]oxazolo[5,4-d]pyrimidine-7-thiones Va–Vc and 2-aryl-6H,7H-[1,3]thiazolo[5,4-d]pyrimidine-7-thiones VIa–VIc. The reactions sequence I→II→IV→V has as the initial reaction that of 2-aroylaminomalonodiamides Ia–Ic with ethyl formate in the presence of sodium ethoxide to form 5-aroylamino-6-hydroxypyrimidin-4-ones IIa– IIc. The C NMR spectra of these compounds contain the characteristic signals of the C and C atoms of the pyrimidine ring in the ranges of 102.87–103.34 and 165.75–165.85 ppm, respectively. In the H NMR spectra there are no signals of the primary amide groups, and the singlet of СH proton appears in the range of 8.04–8.07 ppm.

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.

Synthesis of new derivatives of 5-amino-1,3-oxazole basing on 3-benzoylamino-3,3-dichloroacrylonitrile

DOI: 10.1134/S1070363207070250 It was shown previously that 2-benzoylamino-3,3dichloroacrylonitrile (I) and its analogs are valuable reagents for heterocyclizations leading to derivatives of mononuclear and condensed heterocycles [1 7]. In our systematic research on such cyclizations we have found two simple transformation sequences I II IV and III III V leading to new derivatives of 5-amino-1,3-oxazole (see scheme).

Recyclization of 2-methoxy-5-morpholino-1,3-oxazole-4-carbonitrile by benzylamine, phenethylamine, and phenylhydrazine

Reaction of 2-methoxy-5-morpholino-1,3-oxazole-4-carbonitrile with benzylamine, phenethylamine and phenylhydrazine results in the new substituted 5-amino-2,3-dihydro-1H-imidazol-2-ones.

Transformation of the Condensation Products of 2-Acylamino-3,3-dichloroacrylonitriles with Imidazole into Pyrazolo(1,5-a)pyrimidine Derivatives

Successive treatment of accessible 2-acylamino-3,3-dichloroacrylonitriles with imidazole and hydrazine hydrate led to the formation of 4-acylamino-3(5)-amino-5(3)-(1H-imidazol-1-yl)pyrazoles, and condensation of the latter with acetylacetone afforded 3-acylamino-2-(1H-imidazol-1-yl)-5,7-dimethylpyrazolo [1,5-a]pyrimidines whose structure was reliably determined by X-ray analysis.

Reaction of 2-aryl(methyl)-4-cyano-5-hydrazino-1,3-oxazoles with aryl Isothiocyanates

Accessible 2-aryl(methyl)-4-cyano-5-hydrazino-1,3-oxazoles add to aryl isothiocyanates. The resulting products undergo recyclization to form new 1,3,4-thiadiazole derivatives bearing an acylamino group on C2 and an (acylamino)(cyano)methyl group on C5. The structure of the new compounds was proved by their IR and 1H NMR spectra, as well as by conversion in other 1,3,4-thiadiazole derivatives.

Reactions of N-(2,2-dichloro-1-cyanoethenyl)-N′-methyl(phenyl)ureas with aliphatic amines

Novel derivatives of 3,3-dichloroprop-2-enenitrile containing methylurea or phenylurea fragments have been synthesized. The obtained N-(2,2-dichloro-1-cyanoethenyl)-N′-methyl(phenyl)ureas undergo intramolecular cyclization in the presence of triethylamine to form 4-(dichloromethylidene)-5-imino-1-methyl (phenyl)imidazolidin-2-ones. Reactions of N-(2,2-dichloro-1-cyanoethenyl)-N′-methylurea with aliphatic amines have afforded 4-(alkylamino)-4-(dichloromethyl)-5-imino-1-methylimidazolidin-2-ones.

Acylation of pyrazolo[3,4- d ][1,2,3]triazin-4-ones

Acylation and sulfonylation of substituted pyrazolo[3,4-d][1,2,3]triazin-4-ones, as well as reactions with acylating agents proceeding via destruction of the triazine ring are studied.