Synthesis of new pyrido[3,4-c]carbazole derivatives

Previously unknown 2-[6-hydroxy-9-(4-methoxyphenyl)-1,2,3,9-tetrahydro-4H-carbazol-4-ylidene]malononitrile was synthesized by the Nenitzescu reaction and was used for the construction of new tetracyclic compounds, viz., pyrido[3,4-c]carbazoles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1600–1604, September, 2006.     

Calculation of electronic spectra of pyrido [2,3-d]pyridazine and pyrido[3,4-d]pyridazine

The electronic spectra of pyrido[2,3-d]pyridazine and pyrido[3,4-d]pyridazine have been calculated by the P method and the RP method previously used for azines. The results are in good agreement with experimental data and with the previous conclusions.     

Synthesis of pyrido[3,4-d] benzazepines

The synthesis of some derivatives of the novel heterocyclic ring system pyrido[3,4-d][1]benzazepine is reported. Thus, pyrido[3,4-d][1]benzazepin-7-one 6 was prepared by cyclisation of the Michael adduct 5 with ammonium ferric sulfate. Reaction of 6 with phosphorus pentasulfide gave the thiolactam 7 , which after methylation and subsequent reaction with amines furnished the amidines 10 .     

The synthesis of a pyrido[3,4-d]pyrimidine analog of pteroic acid

A multistep synthesis of ethyl 5-amino-2-methyIpyridine-4-carboxylate (5a) starting from ethyl acetopyruvate and nitroacetamide is described. The condensation of 5a with benzoylcyanamide gave 2-amino-3-benzoyl-6-methylpyrido[3,4-d]pyrimidin-4(3H) one (10), which could be hydrolyzed in alkali to give 2-amino-4-hydroxy-6-methylpyrido[3,4-d]pyrimidine (9). Free radical bromination of 10 in bromotrichloromethane gave a mixture of the bromo- and chloromethyl- derivatives (11). Fusion of 11 with ethyl p-aminobenzoate, followed by alkaline hydrolysis gave the corresponding pteroic acid analog (12).     

Pyridazines. XLI synthesis of novel pyrido[3,4-d]pyridazine derivatives from 4,5-disubstituted pyridazines

Pyrido[3,4-d]pyridazines 2–5, 21 bearing one, two, or three aryl substituents in the pyridine moiety are shown to be conveniently accessible from 4-aroyl-5-methylpyridazines or 4,5-diaroylpyridazines, respectively, by condensation reactions with appropriate C-N fragments. In addition, the novel pyridazine-annelated pyridones 24, 25 were found to be easily available from ethyl 5-methyl-4-pyridazinecarboxylate.     

A novel synthesis of flourinated pyrido [2,3-d] pyrimidine derivatives

Flourinated 4-imino-3,5,7-trisubstituted-pyrido [2,3-d] pyrimidine-2(1H) thiones have been synthesised in good yields by the reaction of 2-amino-3-cyano-4,6- disubstituted-pyridines with various arylisothiocyanates. These new type of products have been characterised by elemental analysis, IR, ¹H and ¹⁹F NMR spectral studies.     

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.     

Regioselective synthesis of pyrido[2,3-d]pyrimidines

The reaction of diethyl ethoxymethylenemalonate ( 1 ) and 6-amino-1,3-dimethyluracil ( 2 ) was determined to be regioselective. Under acidic conditions the product was the previously isolated 7-oxopyrido[2,3-d]pyrimidine ( 3 ), while in the presence of one equivalent of base followed by thermal cyclization, the isomeric 5-oxopyrido[2,3-d]pyrimidine ( 5 ) is formed.     

Efficient synthesis and In Silico study of some novel pyrido[2,3-d][1,2,4]triazolo[4,3-a]pyrimidine derivatives

A novel series of 1,5-dihydropyrido-triazolo-pyrimidine derivatives were prepared by cyclocondensation of 2-thioxo-pyrido[2,3-d]pyrimidines (prepared from reaction of chalcone with 6-aminothiouracil) with a variety of hydrazonoyl chlorides. Based on spectroscopic evidence and their chemical syntheses, the structures of the newly prepared compounds were elucidated. Designated compounds are forced for molecular docking by using MOE 2014.010 Package software; one of in silico study tools. Synthesized compounds are targeting Human Cyclin-defendant Kinase 2 (CK2) PDB ID (1PXO.Protein data bank) due to its important role in controlling the human cell cycle and also for meiosis.     

Synthesis of new pyrido[2,3-d]pyrimidine derivatives

The mutual condensation of 4-aminouracil or 2,4-diamino-6-hydroxypyrimidine with bisacetonitrile and aldehydes was used to synthesize 2,4-dioxo-5-R-7-methyl-6-cyano-1,2,3,4,5,8-hexahydropyrido[2,3-d]pyrimidine and 2-amino-4-oxo-5-R-7-methyl-6-cyano-3,4,5,8-tetrahydropyrido[2,3-d]pyrimidine derivatives, which were oxidized with chromic anhydride to the corresponding 2,4-dioxo-5-R-7-inethyl-6-eyano-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidine and 2-amino-4-oxo-5-R-7-methyl-6-cyano-3,4-dihydro[2,3-d]pyrimidines. The IR and UV spectra of the synthesized compounds were recorded.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 422–425, March, 1972.     

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.     

Synthesis of derivatives of pyrido[3,4-b]- and azepino[3,4-b]pyrrolo[2,3-d]pyrimidines from enamines of α-oxo lactams

The reaction of enamines of some -oxo lactams with 1,3-dimethyl- and 1,3-dibenzyl-4-hydrazinouracils gave the uracilyl-4-hydrazones of these lactams, the catalytic and thermal indolization of which yielded derivatives of pyrido[3,4-b]- and azepino[3,4-b]pyrrolo[2,3-d]pyrimidines. Some reactions of the latter were studied.Communication XXVIII from the series Investigation of Lactams. See [1] for communication XXVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1398–1403, October, 1977.     

Solvent-free combinatorial synthesis of tetrazolo[1,5-a]thiopyrano[3,4-d]pyrimidine derivatives

A series of novel tetrazolo[1,5-a]thiopyrano[3,4-d]pyrimidine derivatives were synthesized by reaction of aryl aldehyde, 2H-thiopyran-3,5(4H,6H)-dione, and 5-aminotetrazole under solvent-free conditions. The features of this procedure are mild reaction conditions, high yields, and operational simplicity.     

Synthesis and transformations of some pyrido[2,3-d]pyrimidines

A new synthetic approach for pyrido[2,3-d]pyrimidine 3-oxides and other pyrido[2,3-d]pyrimidines has been developed. This bicyclic system readily undergoes ring opening to give a variety of products, depending on the reagent and reaction conditions.

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Synthesen und Umwandlungen einiger Pyrido[2,3-d]pyrimidine

Zusammenfassung Synthesen von Pyrido[2,3-d]pyrimidin-3-oxiden und einigen anderen Pyrido[2,3-d]pyrimidinen werden beschrieben. Das bicyclische System reagiert leicht unter Ringöffnung, wobei entsprechend den Reaktionsbedingungen und Reagenzien verschiedene Produkte entstehen.

     

The synthesis of pyrazino[2,3-d]pyridazine and some of its derivatives

Pyrazino[2,3-d]pyridazine (I) was synthesized by two different routes. 5, 8-Dihydroxy-pyrazino[2, 3-d]pyridazine (IV) was converted to 5, 8-dichloropyrazino[2, 3-d]pyridazine (V) and 5, 8-dibromopyrazino[2, 3-d]pyridazine (Va). When V was treated with various benzyl mercaptans and alkoxides the corresponding disubstituted derivatives were obtained. Compound V when allowed to react with aromatic amines gave 5, 8-bisamino-pyrazino[2,3-d]pyridazines, however, with aliphatic amines only mono substituted products were obtained substituted in the 8-position. The reaction of pyrazine-2, 3-dinitrile with hydrazine gave 5, 8-diaminopyrazino[2, 3-d]pyridazine (X).     

An improved synthesis of pyrido[2,3-d]pyrimidines

An improved and efficient synthesis of 1,3-dialkylpyrido[2,3-d]pyrimidine-2,4-(1H,3H)-diones from 6-methylaminouracils and methyl propiolate or diethyl ethoxymethylenemalonate is described.     

The synthesis of 1,2,5-thiadiazolo[3,4-d] pyridazines

A number of previously unreported 1,2,5-thiadiazolo[3,4-d]pyridazines in this relatively unexplored ring system have been reported, charaeterized and screened for antibacterial and antifungal activity.