Electrophilic heterocyclization of 6-alken(yn)ylsulfanyl-pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

6-Allylsulfanyl-1-arylpyrazolo[3,4-d]pyrimidin-4(5H)-ones react with iodine and sulfuric acid to give angular pyrazolothiazolopyrimidine derivatives. The reaction of 6-(prop-2-yn-1-ylsulfanyl)-1-(4-tolyl)-pyrazolo[3,4-d]pyrimidin-4(5H)-one with sulfuric acid gives angularly fused pyrazolo[4,3-e][1,3]thiazolo-[3,2-a]pyrimidin-4-one, whereas in the reaction with sodium methoxide linearly fused pyrazolo[3,4-d][1,3]-thiazolo[3,2-a]pyrimidin-4-one was formed. Linearly fused pyrazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazole derivatives were also obtained by reaction of 1-aryl-6-(3-phenylprop-2-en-1-ylsulfanyl)pyrazolo[3,4-d]pyrimidin-4(5H)-ones with sulfuric acid.     

Modified synthesis of some 1-(pyrimidin-2-yl)-3-methyl-4-arylidenepyrazol-5(4<Emphasis Type="Italic">H</Emphasis>)-ones

2-[3-Methyl-4(4-dialkylaminobenzylidene)-5-oxo-4,5-dihydropyrazol-1-yl]cyclopenta[d]pyrimidin-4(3H)-ones were synthesized by consecutive transformation of 2-hydrazinocyclopenta[d]pyrimidin-4(3H)-one prepared from benzylideneaminoguanidine and ethyl 2-oxocyclopentanoate.     

Transformations of 3-alkyl-4-(methoxyphenyl)-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-5-diazonium salts

The coupling of 3-alkyl-4-(methoxyphenyl)-1H-pyrazole-5-diazonium salts with acetylacetone followed by cyclization of the formed heterylhydrazones resulted in pyrazolo[5,1-c][1,2,4]triazines. The 4-(3,4-dimethoxyphenyl)-3-methyl-1H-pyrazole-5-diazonium salt was not involved into a similar reaction but suffered an intramolecular azo coupling giving pyrazolo[3,4-c]-cinnoline.     

One-Step Three-Component Synthesis of New 2,5,6,7-Functionalized 5,8-Dihydropyrido-[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

One-step three-component cyclocondensation of 2,6-disubstituted pyrimidin-4(3H)-ones with 1,3-dicarbonyl compounds and some aromatic and heterocyclic aldehydes on heating or under microwave irradiation afforded new functionally substituted 5,8-dihydropyrido[2,3-d]pyrimidin-4(3H)-ones. Conventional heating was found to be more advantageous. The effects of the 2-substituent in the initial pyrimidin-4(3H)-one and the nature of the dicarbonyl component on the product structure and yield were analyzed.     

Synthesis and properties of ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-3-carboxylates

Ethyl 1-aryl-4-acetyl-5-methyl-1H-pyrazole-3-carboxylates reacted with phenylhydrazine to give the corresponding hydrazones, ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1H-pyrazole-3-carboxylates, which were converted to ethyl 1′-aryl-4-formyl-5′-methyl-1-phenyl-1H,1′H-3,4′-bipyrazole-3′-carboxylates by treatment with the Vilsmeier–Haack reagent. No indole derivatives were formed from the same hydrazones under the Fischer reaction conditions, but cyclization to 2-aryl-3,4-dimethyl-6-phenyl-2,6-dihydro-7H-pyrazolo[3,4-d]pyridazin-7-ones was observed.     

Synthesis and Biological Activity of 3,4-Diaryl-5-[4-(acetylsulfamoyl)phenyl]-4,5-dihydropyrrolo[3,4-<Emphasis Type="Italic">c</Emphasis>]pyrazol-6(2<Emphasis Type="Italic">H</Emphasis>)-ones and Their Sodium Salts

3,4-Diaryl-5-[4-(acetylsulfamoyl)phenyl]-4,5-dihydropyrrolo[3,4-c]pyrazol-6(2H)-ones were synthesized be reaction of 5-aryl-4-aroyl-1-[4-(acetylsulfamoyl)phenyl]-3-hydroxy-1H-pyrrole-2(5H)-ones with hydrazine hydrate in glacial acetic acid, and their sodium salts were obtained by treatment with sodium methoxide in methanol–DMF (1: 1). Analgesic and anti-inflammatory activity and acute toxicity of the synthesized compounds were studied.     

Synthesis of 4-halo-3-(phenylamino)furo[3,4-<Emphasis Type="Italic">c</Emphasis>]pyridin-1(3<Emphasis Type="Italic">H</Emphasis>)-ones

A method was developed for the synthesis of 4-halo-3-(phenylamino)-furo[3,4-c]pyridin-1(3H)-ones by the reaction of 4-halo-3-hydroxyfuro[3,4-c]pyridin-1(3H)-ones with aniline at room temperature.     

Molecular design of pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyridazines

Reactions of arenediazonium chlorides with ethyl 2-methyl-and 2-chloro-4-oxobutanoates gave, respectively, ethyl 2-(arylhydrazono)propanoates and chloro(arylhydrazono)acetates. Ethyl 2-(arylhydrazono)-propanoates reacted with the Vilsmeier-Haak reagent to give ethyl 1-aryl-4-formyl-1 H-pyrazole-3-carboxylates. Ethyl 1-aryl-4-acetyl-5-methyl-1H-pyrazole-3-carboxylates were obtained by reaction of chloro(arylhydrazono) acetates with acetylacetone. Reactions of the obtained pyrazole derivatives with hydrazine and methylhydrazine led to the formation of the corresponding 3,4-R ₂ ¹ -6-R²-2-aryl-2,6-dihydro-7H-pyrazolo-[3,4-d]pyridazin-7-ones (R¹, R² = H, Me) which were subjected to alkylation and sulfurization.     

Acylation of pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>][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.     

New application of heterocyclic diazonium salts. Synthesis of pyrazolo[3,4-d][1,2,3]triazin-4-ones and imidazo[4,5-d][1,2,3]triazin-4-ones

The pyrazolo[3,4-d][1,2,3]triazin-4-ones 3 and imidazo[4,5-d][1,2,3]triazin-4-ones 4 are analogs structurally related to purines that have showed a wide and significant variety of biological activity. These compounds were synthesized by one-pot diazotization of 5-amino-1H-pyrazole-4-carbonitriles 1 and 5-amino-1H-imidazole-4-carbonitriles 2, respectively.     

New Synthesis of Pyrano[4,3-<Emphasis Type="Italic">d</Emphasis>]pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridines

A new efficient method has been developed for the synthesis of highly biologically active pyrano-[4,3-d]pyrazolo[3,4-b]pyridines on the basis of Smiles rearrangement of ethyl [(8-alkyl(aryl)-5-cyano-3,3-dimethyl-3,4-dihydro-1H-pyrano[3,4-c]pyridin-6-yl)oxy]acetates. Intermediate acetohydrazides have also been isolated. The proposed procedure is advantageous due to the possibility of avoiding experimentally difficult chlorination stage.     

Synthesis,S-alkylation,and fungicidal activity of 4-(benzylideneamino)thioglycolurils

A series of 1,3-disubstituted 4-benzylideneamino-5-thioxohexahydroimidazo[4,5-d]imidazol-2(1H)-ones (thioglycolurils) was synthesized via the reaction of 5,7-disubstituted 3-thioxoperhydroimidazo[4,5-e]-1,2,4-triazin-6-ones with hydroxy-, alkoxy-, and fluorocontaining benzaldehyde derivatives. An alkylation of the obtained thioglycolurils with methyl iodide or 4-bromobenzyl bromide provided the corresponding 6-benzylideneamino-5-alkylsulfanyl-3,3a,6,6a-tetrahydroimidazo[4,5-d]imidazol-2(1H)-ones. The fungicidal activity of some synthesized compounds against pathogens causing diseases of agricultural crops was studied.     

Fused Pyrimidine Systems: XVII. Imidazo- and Pyrimidopyrido[3,2-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

2-(Allylamino)pyrido[3,2-d]pyrimidin-4(3H)-one was converted to linearly fused dihydroimidazo- [1,2-a]pyrido[3,2-d]pyrimidine on heating in polyphosphoric acid, whereas its reactions with molecular iodine and chlorosulfanylarenes afforded mainly angularly fused analogs. 2-(Cinnamylamino)pyrido[3,2-d]pyrimidin- 4(3H)-one reacted with polyphosphoric acid and chlorosulfanylarenes to give linear pyrido[3,2-d]pyrimido-[1,2-a]pyrimidinones, and its iodocyclization led to the formation of angularly fused derivative.     

Synthesis of Substituted Pyridazin-3-ones, 1,2-Oxazin-3-ones,and Furopyrimidines from (Arylmethylidene)furan-2(3<Emphasis Type="Italic">H</Emphasis>)-ones

Reactions of 5-substituted 3-(arylmethylidene)furan-2(3H)-ones with hydrazine hydrate, hydroxylamine, and guanidine involved opening of the furanone ring. Their hydrazinolysis under mild conditions afforded acyclic 4-oxoalkanoic acid hydrazides which underwent heterocyclization to substituted pyridazinones in boiling ethanol. The presence of an alkyl substituent in the 5-position of the initial furanone favored heterocyclization with the formation of pyrazolidinone derivatives. The reactions of 3-(arylmethylidene)furan-2(3H)-ones with hydroxylamine and guanidine also produced new six-membered heterocycles, 2H-1,2-oxazin-3(4H)-ones and 4,6-disubstituted 3,4-dihydrofuro[2,3-d]pyrimidin-2-amines, respectively.     

Iodocyclization of 2-[allyl(methallyl)sulfanyl]-6-(trifluoromethyl)pyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

Iodination of 2-[allyl(methallyl)sulfanyl]-6-(trifluoromethyl)pyrimidin-4(3H)-ones was accompanied by cyclization to 2,3-dihydro[1,3]thiazolo[3,2-a]pyrimidin-4-ium triiodides. 3-(Iodomethyl)-3-methyl- 7-oxo-5-(trifluoromethyl)-2,3-dihydro[1,3]thiazolo[3,2-a]pyrimidin-4-ium triiodide was reduced with sodium iodide to 3,3-dimethyl-7-oxo-5-(trifluoromethyl)-2,3-dihydro[1,3]thiazolo[3,2-a]pyrimidin-4-ium iodide.     

Synthesis of polyazaheterocycles containing linearly bound 1,2,4-thiadiazole using enaminones

A reaction of N-substituted 5-amino-3-(2-oxopropyl)-1,2,4-thiadiazoles with dimethylformamide dimethyl acetal gave 3-(5-amino-1,2,4-thiadiazol-3-yl)-4-(dimethylamino)but-3en-2-ones, whose cyclization with hydrazine, guanidine, 1H-pyrazol-5-amines and 6-aminopyrimidin-4(3H)-ones led to 3-methyl-1H-pyrazole, 4-methylpyrimidin-2-amine, 5-methyl3-arylpyrazolo[1,5-a]pyrimidines, and 5-methyl-2-R-pyrido[2,3-d]pyrimidin-4(3H)-ones containing a 5-amino-1,2,4-thiadiazole fragment linearly bound at position 3.     

5,7-Dihydropyrrolo[3,4-<Emphasis Type="Italic">d</Emphasis>][1,2]diazepin-1(2<Emphasis Type="Italic">H</Emphasis>)-ones. Synthesis and transformations

A preparative procedure has been developed for the synthesis of substituted 5,7-dihydropyrrolo-[3,4-d][1,2]diazepines by recyclization of 6-phenylpyrano[3,4-c]pyrrol-4(2H)-one with hydrazine hydrate. The stability of the seven-membered ring in the products under acidic conditions, alkylation, and heteroring fusion to the diazepine ring have been studied.     

New general synthesis of benzo[4,5]imidazo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine and benzo[4,5]imidazo[2,1-<Emphasis Type="Italic">b</Emphasis>]quinazoline derivatives

The reactions of benzene-1,2-diamine with 5-substituted 2-(alkylsulfanyl)-4-methylpyrimidin-6(1H)-ones and 2-(propylsulfanyl)- and 5-iodo-2-(propylsulfanyl)-3,4-dihydroquinazolines at 175–185°C under solvent-free conditions unexpectedly afforded benzo[4,5]imidazo[1,2-a]pyrimidine, benzo[4,5]imidazo[2,1-b]-quinazoline, and 2,2′-(benzene-1,2-diyldiimino)bis[pyrimidin-4(3H)-ones]. The described reaction is the first example of synthesis of these heterocyclic systems by fusion of benzimidazole to pyrimidine or quinazoline and is likely to follow ANRORC mechanism.     

Synthesis of New Cyclopenta[<Emphasis Type="Italic">b</Emphasis>]quinoline Derivatives

A series of new 11-(R-phenyl)-8,9-dihydro-7H-benzo[f]cyclopenta[b]quinolin-10(11H)-ones and 7,14-bis(R-phenyl)-2,3,9,10,11,14-hexahydrocyclopenta[2,3]quinolino[8,7-h]cyclopenta[b]quinoline-1,8(4H,7H)-diones were synthesized by three-component condensation of naphthalen-2-amine or naphthalene- 1,5-diamine with substituted benzaldehydes and cyclopentane-1,3-dione in one step through intermediate formation of unstable arylaminoketoenol.     

Convenient regioselective reaction in presence of H<Subscript>3</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript>: synthesis and characterization of pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]quinoline-3,5-diones

We describe regioselective synthesis of pyrazolo[3,4-b]quinoline derivatives by multicomponent reaction of dimedone, 5-aminopyrazolone, and aromatic aldehydes in presence of H₃PW₁₂O₄₀ as catalyst. When this multicomponent reaction was investigated without catalyst under reflux conditions, a mixture of products was obtained, while the reaction successfully proceeded to formation of pyrazolo[3,4-b]quinoline in presence of H₃PW₁₂O₄₀. Good product yield, short experimental time, and low-cost catalyst provide convenient synthesis for formation of pyrazolo[3,4-b]quinoline pharmacological compounds.