Aminoethyl derivatives of 4-substituted pyrazolo[3,4-d]pyrimidines

New 3-aminoethyl derivatives of pyrazolo[3,4-d]pyrimidine were synthesized by reduction of 3-cyanomethylpyrazolo[3,4-d]pyrimidines with hydrazine hydrate in the presence of Raney nickel in alcohol.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 846–847, June, 1972.     

The synthesis of substituted pyrido[1′,2′:1,5]pyrazolo[3,4-d]pyrimidines

A convenient synthesis of derivatives of the pyrido[1′,2′:1,5]pyrazolo[3,4-d]pyrimidine ring system from readily available 2-amino-3-cyano-5,7-diphenylpyrazolo[1,5-a]pyridine I and carbon disulfide, aryl isothiocyanates or nitriles is described. Derivatives of compound I undergo cyclization to the titled ring system by action of dimethylformamide dimethylacetal or hydrogen sulfide followed by treatment with triethylamine.     

Chemical transformations of trisubstituted pyrazolo[3,4-d]pyrimidines and their 1-ribosides

A number of 3,4,6-trisubstituted pyrazolo[3,4-d]pyrimidines and their 1-ribosides were synthesized from 3-cyano-4,6-dimethylmercaptopyrazolo [3,4-d]pyrimidine. The cyano group was converted to thiocarbamoyl, imido ester, carboxamidoximno, carboxamidrazono, carboxy, and amidino groups. The 4-methylmercapto group was replaced by mercapto, methoxy, amino, and hydrazino groups. The reactivities of methylmercapto and 3-cyano groups in substituted pyrazolo [3,4-d] pyrimidines and the corresponding nucleosides with respect to nucleophilic agents were compared. The introduction of a ribose residue in the 1 position facilitates nucleophilic addition to the 3-cyano group and replacement of the 4-methylmercapto group. High resistance of the 6-methylmercapto group to the action of nucleophilic agents and higher reactivity of the cyano groups as compared with methylmercapto groups were observed. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 243–250, February, 1980.     

Synthesis and anticancer evaluation of some new pyrazolo[3,4-d][1,2,3]triazin-4-ones,pyrazolo[1,5-a]pyrimidines,and imidazo[1,2-b]pyrazoles clubbed with carbazole

Carbazole represents as a promising template for cancer treatment as it exists in the skeleton of numerous man-made and natural anticancer agents. In this regard, new sets of novel functionalized pyrazolo[3,4-d][1,2,3]triazin-4-ones 6a-e and 10a-e , pyrazolo[1,5-a]pyrimidines 16a,b and imidazo[1,2-b]pyrazoles 20a,b and 23a-c having carbazole moiety were efficiently synthesized, characterized, and mechanistically discussed. They were also evaluated against three human cancer cell lines (HCT-116, HepG-2, and MCF-7) and one standard human cell line (REP1) for their in vitro anticancer activity. The results declared that seven compounds 10d , 10e , 12b , 12d , 12e , 16a , and 23a had potent anticancer activity, having IC₅₀ values in the range 2.97 to 10.31 μM. The most effective compounds 10d and 10e inhibited the growth of all screened cancer cell lines and did not reveal human toxicity.     

Synthesis and in vitro anticancer activity of pyrazolo[1,5-a]pyrimidines and pyrazolo[3,4-d][1,2,3]triazines

A novel series of pyrazolo[1,5-a]pyrimidines 14a–j and pyrazolo[1,5-a]quinazolines 18a, b were synthesized via condensation of 5-amino-1H-pyrazoles 10a, b with 3-(dimethylamino)-1-aryl-prop-2-en-1-ones 11a–e and 2-((dimethylamino)methylene)-5,5-dimethylcyclohexane-1,3-dione (15), respectively, in glacial acetic acid. Finally, treatment of 10a, b with sodium nitrite (NaNO₂) afforded pyrazolo[3,4-d]triazines 20a, b. Structures of compounds were confirmed by their spectral data. These compounds were screened for their in vitro cytotoxic activities against human cancer cell lines (HepG-2 and MCF-7) using 3-[4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The results reveal that, the compounds 14b and 14h were the most potent in comparison with doxorubicin. The structure–activity relationship was discussed.     

Synthesis of 3-aryl-6H-isoxazolo[3,4-d]pyrazolo[3,4-b]pyridines and 3-aryl-6H-isoxazolo[5,4-d]pyrazolo[3,4-b]pyridines

The synthesis and characterization of a number of 3-aryl-6H-isoxazolo[3,4-d]pyrazolo[3,4-b]pyridines and 3-aryl-6H-isoxazolo[5,4-d]pyrazolo[3,4–6]pyridines from common precursors, 5-benzoyl-4-chloro-1H-pyrazolo-[3,4-b]pyridines, has been described. The structures were determined by unambiguous chemical synthesis and by isolation and ¹³C nmr analysis of some key, isolated, intermediates. The ability of these compounds to displace [3H]flunitrazepam from CNS binding sites was also observed.     

Nitroxyl derivatives of pyrazolo [3,4-d]pyrimidine

Conclusions Pyrazolo[3,4-d]pyrimidine nitroxyl derivatives having different distances between the paramagnetic center and the pyrazolopyrimidine ring have been prepared for the first time.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2763–2766, December, 1982.     

Synthesis of substituted pyrazolo[4,5-d]thiazoles

With phosphorus pentasulfide 1-phenyl-3-methyl-4-acetylaminopyrazol-5-one and 1, 3-diphenyl-4-acetylamino-5-acetoxypyrazole give, respectively, 2, 4-dimethyl-6-phenylpyrazolo[4, 5-d]thiazole and 2-methyl-4, 6-diphenylpyrazolo[4, 5-d]thiazole.     

Catalyst free synthesis of fused pyrido[2,3-d]pyrimidines and pyrazolo[3,4-b]pyridines in water

A one-pot,three-component condensation reaction of an aldehyde,benzoyl acetonitrile(3-oxo-3-phenylpropane nitrile) and 6- amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione or 3-methyl-1-phenyl-1H-pyrazol-5-amine in water to give fused pyrido[2,3- d]pyrimidines and pyrazolo[3,4-b]pyridines in high yields without any catalyst,is described.     

NMR analysis of a series of substituted pyrazolo[3,4-d] pyrimidines-4-amines

A series of 21 substituted pyrazolo[3,4-d]pyrimidines-4-amines were studied by (1)H and (13)C NMR. The application of two-dimensional techniques, HMQC and HMBC, allowed the complete assignment of the spectra for all the compounds.     

Synthesis of 3,4-diamino-1H-pyrazolo[3,4-d]pyrimidines

The reaction of 4-(amino-substituted)-2-methylthio-6-chloropyrimidine-5-carbonitriles with hydrazine and methylhydrazine was used to synthesize 3, 4-diamino-6-methylthio-1H-pyrazolo[3, 4-d]pyrimidines. It was shown that the formation of pyrazolopyrimidines proceeds through intermediate 6-hydrazinopyrimidine-5-carbonitriles.Department of Organic Chemistry, Vil'nyus University, Vil'nyus 2006. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 831–836, June, 1996. Original article submitted February 9, 1996.     

Bromination of 4-hydroxypyrazolo[3,4-d]pyrimidines

The bromination of 4-hydroxypyrazolo[3,4-d] pyrimidine and its N-methyl analogs leads to the corresponding 3-bromo derivatives. Inhibition of the reaction by 4-hydroxypyrazolo[3,4-d] pyrimidine was observed during a study of the bromination kinetics; this is explained by complexing.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 397–402, March, 1978.The authors thank V. V. Ogorodnikova for recording the UV spectra and F. S. Shub for assistance in discussion of the results of the kinetic experiments.     

Halogenation of some substituted 3-allyl-2-mercapto-3,4-dihydrothieno[2,3-d]pyrimidines

The bromination and iodination of substituted 3-allyl-2-mercapto-4-oxo-3,4-dihydrothieno[2,3-d]pyrimidines have been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1289–1290, September, 1973.     

Some reactions of 4-aminopyrazolo[3,4-d]pyrimidines

New 3-bromo and 1,4-diaminomethyl derivatives of 4-aminopyrazolo[3,4-d]pyrimidine were obtained by bromination and aminomethylation, respectively. 4-Bromopyrazolo[3,4-d]pyrimidines were synthesized for the first time by diazotization of 4-aminopyrazolo[3,4-d]pyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 982–984, July, 1982.