A new synthesis for 1,2,4-triazolo[1,5-a]-pyridines and 1,2,4-triazolo[1,5-a]isoquinolines

Summary Condensation of cyano acid hydrazide1 with cyclopentanone in refluxing ethanolic piperidine yields hydrazone2. With mixtures of aliphatic aldehydes and different active methylene reagents,2 reacts to 1,2,4-triazolo[1,5-a]pyridines (8a–f). Compound2 also reacts with arylidenes9a–g to give triazolopyridines10a–g. Reaction of2 with aromatic aldehydes affords compounds13a–c. Diazotation of2 with aryldiazonium chloride in ethanol at 0 °C leads to the azo adducts15a–d. The thieno-1,2,4-triazolopyridine16 is obtained by reaction of8a with elementary sulfur.16 undergoes cycloaddition with -nitrostyrene, maleic anhydride, N-arylmalemide, and acrylonitrile yielding the isoquinolines21–24. All new compounds have been characterized by their IR,¹H NMR, and mass spectra.

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Ein neuer Syntheseweg für 1,2,4-Triazolo[1,5-a]pyridine und 1,2,4-Triazolo[1,5-a]isochinoline

Zusammenfassung Kondensation des Cyanohydrazids1 mit Cyclopentanon in ethanolischem Piperidin bei Rückflußtemperatur ergibt das Hydrazon2. Mit Gemischen aus aliphatischen Aldehyden und verschiedenen Verbindungen mit aktiven Methylengruppen reagiert2 zu 1,2,4-Triazolo[1,5-a]pyridinen (8a–f). Verbindung2 reagiert außerdem mit den Arylidenen9a–g zu den Triazolopyridinen10a–g. Umsetzung von2 mit aromatischen Aldehyden führt zu den Verbindungen13a–c. Diazotierung von2 mit Aryldiazoniumchloriden in Ethanol bei 0°C ergibt die Azoaddukte15a–d. Das Thieno-1,2,4-triazolylpyridin16 erhält man durch Reaktion von8a mit elementarem Schwefel.16 geht it -Nitrostyrol, Maleinsäureanhydrid, N-Arylmaleimid und Acrylnitril eine Cycloaddition zu den Isochinolinen21–24 ein. Alle neuen Verbindungen wurden durch ihre IR-,¹H-NMR- und Massenspektren charakterisiert.

     

Tricyclic heteroaromatic systems. 5H-1,2,4-triazolo[5,1-c][1,4]benzodiazepine

The synthesis of the new tricyclic heteroaromatic system 5H-1,2,4-triazolo[5,1-c][1,4]benzodiazepine, diazaanalogue of 5H-pyrrolo[2,1-c][1,4]benzodiazepine, which is the common feature of some antitumor antibiotics, is reported. The structure of the new tricyclic system and of some of its key intermediates is assigned by means of nuclear magnetic resonance studies.     

Stable 1,2,4-triazolo[1,5-a]-pyrimidinium salts

2,3-Diamino-5,7-diaryl-1,2,4-triazolo[1,5-a]pyrimidinium salts have been synthesized by the cyclocondensation of 3,4,5-triamino-1,2,4-triazole with 1,3-diaryl-2,3-propanes, and their structures and chemical properties have been studied.Kharkov State University, Kharkov 310077, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, 796–804 June, 1999.     

Tricyclic heteroaromatic ring systems IV. Synthesis and reactions of 4H-Pyrazolo[1,5-a]benzimidazole

The 4H-Pyrazolo[1,5-a]benzimidazole ring system was prepared by an intramolecularUllmann arylation of 4-substituted 1-(o-aminophenyl)pyrazole while other derivatives were obtained by functional group modifications. Some electrophilic substitutions (nitration, bromination) and alkylations were also carried out.

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Tricyclische heteroaromatische Ringsysteme, 4. Mitt.: Synthese und Reaktionen von 4H-Pyrazolo[1,5-a]benzimidazolen

Zusammenfassung Das 4H-Pyrazolo[1,5-a]benzimidazol-System wurde mittels intramolekularerUllmann-Arylierung von 4-substituierten 1-(o-Aminophenyl)pyrazolen hergestellt; weitere Derivate wurden dann durch Modifikation funktioneller Gruppen synthetisiert. Einige elektrophile Substitutionen (Nitrierung, Bromierung) und Alkylierungen wurden ebenfalls durchgeführt.

     

Synthesis of 1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonamides

The 1,2,4-triazolo[1,5-a]pyrimidine-2-sulfonamides are a new class of highly active herbicides. A novel cyclization method for the synthesis of these compounds is discussed.     

A novel rearrangement to 1,2,4-triazolo[1,5-a]quinoxalines

Reactions of benzyl bromide or benzyl cinnamate with N-(benzotriazol-1-ylmethyl)arylimidoyl chlorides (2a,b) in the presence of t-BuOK occur with opening of the benzotriazole ring affording 1,2,4-triazolo[1,5-a]quinoxalines (3a,b). A possible reaction mechanism is discussed.     

Improved synthesis of 2-amino-1,2,4-triazolo[1,5-a]pyrimidines

An improved procedure is suggested for preparing 2-amino-1,2,4-triazolo[1,5-a]pyrimidines from 3,5-diamino-1,2,4-triazole and unsaturated aromatic ketones, with acetyl protection of the amino group in the step of oxidation of 2-amino-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines.     

2-Substituted 7-amino-1,2,4-triazolo[1,5-a]-[1,3,5]triazines

3-Substituted 5-amino-1-guanyl-1,2,4-triazoles have been obtained which, on reaction with orthoformic ester or 100% formic acid, form 2-substituted 7-amino-1,2,4-triazolo[1,5-a]-[1,3,5]triazines.     

新型三环系稠杂环[1,2,4]-三唑并[1,5-a][1]-苯并氮杂(艹卓)及[1,2,4]-三唑并[1,5-a]-喹啉的合成

α-四氢萘酮的乙氧羰基腙(1)经LTA氧化, 得到α-偶氮-α-乙酰氧基化合物2. 在AlCl3作用下, 化合物2脱去乙酰氧基产生重氮正离子中间体3, 再经与腈的1,3-偶极环加成、 [1,2]-迁移扩环、碱性水解和与苦味酸作用, 得到新型[1,2,4]-三唑并[1,5-a][1]苯并氮杂(艹卓)苦味酸盐6a～6c. 以2,3-二氢-1-茚酮为底物, 采用相同的合成路线, 合成了1,2,4-三唑并[1,5-a]-二氢喹啉苦味酸盐12a～12c.     

新型三环系稠杂环[1,2,4]-三唑并[1,5-a][1]-苯并氮杂及[1,2,4]-三唑并[1,5-a]-喹啉的合成

α-四氢萘酮的乙氧羰基腙(1)经LTA氧化,得到α-偶氮-α-乙酰氧基化合物2.在A lC l3作用下,化合物2脱去乙酰氧基产生重氮正离子中间体3,再经与腈的1,3-偶极环加成、[1,2]-迁移扩环、碱性水解和与苦味酸作用,得到新型[1,2,4]-三唑并[1,5-a][1]苯并氮杂苦味酸盐6a~6c.以2,3-二氢-1-茚酮为底物,采用相同的合成路线,合成了1,2,4-三唑并[1,5-a]-二氢喹啉苦味酸盐12a~12c.     

Tricyclic heteroaromatic systems. 5H-1,2,3-triazolo[5,1-c][1,4]benzodiazepine

The synthesis of the new tricyclic system 5H-1,2,3-triazolo[5,1-c][1,4]benzodiazepine, diaza-analogue of 5H-pyrrolo[2,1-c][1,4]benzodiazepine, which is the common feature of some antitumor antibiotics, is reported. The structure of the new tricyclic system and of some of its key intermediates is assigned by means of a ¹³C nmr study.     

Chemical conversions of 5,7-disubstituted dihydro-1,2,4-triazolo[1,5-a]pyrimidines

Hydrolysis, oxidation, reduction, alkylation, and nitrosation of aromatic-substituted dihydro-1,2,4-triazolo-[1,5-a]pyrimidines have been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1638–1642, December, 1990.     

Synthesis and structure of 4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidines

Kharkov State University, 310077 Kharkov and Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 981–986, July, 1994.Original article submitted May 11, 1994.     

Identification by NMR spectroscopy of some isomeric 1,2,4-triazolo[4,3-a] and [1,5-a]pyrimidines

The title compounds have been prepared with four known procedures. The mixtures of isomers obtained have been separated by countercurrent distribution and the single isomers identified by NMR spectroscopy.     

An unequivocal synthesis of some substituted 1,2,4-triazolo[1,5-a]pyrimidines

An unequivocal synthesis of 5-chloro-7-methyl- (8) and 7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (10) from 2-amino-4-chloro-6-methylpyrimidine (5) through the corresponding amidine6 and formamide oxime7 was developed. It was unambigously shown by comparison of the chemical shifts and the magnitude of coupling constants that the compounds obtained by condensation of 3-amino-1,2,4-triazole (12) and ethyl acetoacetate (13) and some further transformations are isomeric 5-methyl substituted 1,2,4-triazolo[1,5-a]pyrimidines1,9, and11.

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Eine eindeutige Synthese einiger substituierter 1,2,4-Triazolo[1,5-a]pyrimidine

Zusammenfassung Es wurde ein eindeutiger Syntheseweg für 5-Chlor-7-methyl- (8) und 7-Methyl-1,2,4-triazolo[1,5-a]pyrimidin (10) ausgehend von 2-Amino-4-chlor-6-methylpyrimidin (5) über das entsprechende Amidin6 und das Formamidoxim7 entwickelt. Durch Vergleich von chemischen Verschiebungen und Kopplungskonstanten konnte eindeutig gezeigt werden, daß die Verbindungen, die bei der Kondensation von 3-Amino-1,2,4-triazol (12) and Ethylacetoacetat (13), sowie einige weitere Transformationsprodukte, isomere 5-Methylsubstituierte 1,2,4-Triazolo[1,5-a]pyrimidine sind (1,9,11).

     

Nitroazines 18. Arylation and destruction of 6-nitro-1,2,4-triazolo[1,5-a]pyrimidines

6-Ntiro-7-aryl-1,2,4-triazolo[1,5-a]pyrimidines were synthesized by treatment of the corresponding 7-oxo compounds with phosphorus oxychloride in the presence of N,N-dialkylanilines. The 7-(N-methyl-p-methoxyphenylamino) derivatives were formed under the same conditions with N,N-dimethyl-p-anisidine. The nitroarylazolopyrimidines produced underwent destruction to give -nitroacetophenones on treatment with water. The influence of substituenis on the course of the reaction is shown and the mechanism is discussed.For Communication 17 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1546–1554, November, 1992.