Oxamic acid derivaties in heterocyclic synthesis: Preparation of 1,2,4-triazolo[1,5-a]pyrazine derivatives

N-Aryl-N-(α-phenylphenacyl)oxamoyl chlorides react with N³-arylsubstituted amidrazones to give functionalized 1,2,4-triazoles which undergo ring-closure by the action of thionyl chloride to give 1,2,4-triazolo[1,5-a]-pyrazinium chlorides in excellent yields.     

Facile one-pot synthesis of new [1,2,4]triazolo[1,5-a]pyridine derivatives by ultrasonic irradiation

Herein, we report an ultrasonic promoted facile and convenient “one-pot” procedure for the synthesis of new [1,2,4]triazolo[1,5-a]pyridine derivatives 3, 4 and 5, using Amberlite IRA-400, in short reaction times and high yields and its comparison with classical reaction conditions. The structures of new compounds were assigned with the help of analytical ¹H, ¹³C NMR, and mass spectral studies.     

Activated nitriles in heterocyclic synthesis. A novel synthesis of pyrazolo[1,5-a]pyrimidines and pyrano[2,3-c]pyrazoles

Several new pyrazolo[1,5-a]pyrimidines and pyrano[2,3-c]pyrazoles were synthesized viathe reaction of the cinnamonitrile derivatives 1a-c with 5-amino-3-phenylpyrazole ( 1 ), 3-amino-2-pyrazolin-5-one ( 2 ) and 3-amino-1-phenyl-2-pyrazolin-5-one ( 22 ).     

α,β-Unsaturated nitriles in heterocyclic synthesis: Synthesis of some new pyrazolo[1,5-a]pyrimidine derivatives

3-Antipyrinyl-5-aminopyrazole (1) reacted with acrylonitrile to afford 5-amino-1--cyanoethyl-3-antipyrinylpyrazole (2). Compound2 could also be obtained from the reaction of -cyanoethylhydrazine (3) and compound4.2 was readily cyclized into 2-antipyrinyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidin-5-one (5) by acetic-hydrochloric acid.5 could be also obtained from the reaction of1 and methyl acrylate. The reaction of1 and cinnamonitrile derivatives7 a–e resulted in the formation of pyrazolo[1,5-a]pyrimidine derivatives9,11 and12.

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,-Ungesättigte Nitrile in der Heterocyclen-Synthese: Synthese einiger neuer Pyrazolo[1,5-a]pyrimidin-Derivate

Zusammenfassung 3-Antipyrinyl-5-aminopyrazol (1) reagierte mit Acrylnitril zu 5-Amino-1--cyanoethyl-3-antipyrinylpyrazol (2).2 konnte ebenfalls aus der Reaktion von -Cyanethylhydrazin (3) und Verbindung4 erhalten werden.2 wurde mittels Essigsäure-Salzsäure glatt zu 2-Antipyrinyl-4,5,6,7-tetrahydropyrazolo[1,5-a]-pyrimidin-5-on (5) cyclisiert.5 konnte auch aus der Reaktion von1 mit Methylacrylat erhalten werden. Die Reaktion von1 mit Zimtsäurenitrilderivaten7 a–e ergab die Pyrazolo[1,5-a]pyrimidin-Derivate9,11 und12.

     

Activated nitriles in heterocyclic synthesis. A novel synthesis of 1,2,4-tnazol-3-oyl nitriles

Synthesis of 1,2,4-triazoloyl nitriles via reaction of 4-phenylhydrazono-2-phenyl-2-oxazolin-5-one and 4-phenylhydrazono-2-ethoxy-2-thiazolin-5-one with active methylene nitriles was accomplished. Some of the chemical properties of the nitriles obtained are reported.     

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.

     

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.     

Synthesis of 1,2,3-triazolo[1,5-a]pyridine ester derivatives

Lithiation of 1,2,3-triazolo[1,5-a]pyridines 4b and 4c with lithium diisopropylamide (LDA) gave the corresponding lithio derivatives 5b and 5c from which esters 6b and 6c were obtained by treatment with carbon dioxide and then dimethyl sulfate. Lithio derivatives 5a-5c reacted with DMF giving aldehydes 7a-7c. Esters 9a-9c were prepared from aldehydes 7a-7c and carbomethoxymethylenetriphenylphosphorane.     

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.     

Synthesis of [1,2,4]triazoloquinazoline and [1,2,4]-triazolo-1,4-benzodiazepine derivatives

Some [1,2,4]triazolo[1,5-c]quinazolin-5(6H)-ones 7 , the corresponding isomers [1,2,4]triazolo[4,3-c]quinazo-lin-5(6H)-ones and the 5-amino derivatives 8, 9 and 11 have been synthesized starting from the acylamidrazones 5 . The preparation of 5H-[1,2,4]triazolo[1,5-d]-1,4-benzodiazepin-6(7H)-ones 15 and of 5-cyclicaminomethyl-[1,2,4]triazolo[1,5-c]quinazolines 16 and 17 is also reported.     

Synthesis of Novel 2-Methylsulfanyl-4H-[1,2,4]triazolo[1,5-a]quinazolin-5-one and Derivatives

A novel 2-methylsulfanyl-4H-[1,2,4]triazolo[1,5-a]quinazolin-5-one was synthesized using dimethyl-n-cyanoimidodithiocarbonate and 2-hydrazinobenzoic acid as building blocks. Chemical transformation of the inherent lactam moiety in the targeted 2-methylsulfanyl-[1,2,4]triazolo[1,5-a]quinazolin-5-one offered access to a variety of derivatives.     

Activated nitriles in heterocyclic synthesis: Synthesis of 6-thiophen-2-yl and 6-furan-2-ylthiazolo[2,3—a]pyridine derivatives

A variety of new 6-thiophen-2-yl and 6-furan-2-ylthiazolo[2,3—a]pyridine derivatives could be prepared via the reaction of 2-functionally substituted methyl-2-thiazolin-4-one with cyanomethylenethiophen-2-yl and cyanomethylenefuran-2-yl derivatives. The structure of the reaction products was established based on spectral data.

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Aktivierte Nitrile in der Heterocyclen-Synthese: Die Synthese von 6-Thiophen-2-yl-und 6-Furan-2-yl-thiazolo[2,3—a]pyridin-Derivaten

Zusammenfassung Es konnte eine Reihe neuer 6-Thiophen-2-yl- und 6-Furan-2-yl-thiazolo-[2,3—a]pyridine über die Reaktion von 2-funktionell-substituierten Methyl-2-thiazolin-4-onen mit Cyanomethylenthiphen-2-yl bzw. Cyanomethylenfuran-2-yl-Derivaten hergestellt werden. Die Struktur der Reaktionsprodukte wurde mit spektroskopischen Methoden ermittelt.

     

A convenient synthesis of 2-aryl substituted benzo[f] [1,2,4]triazolo[1,5-a]azepine derivatives

A convenient synthetic pathway to 2-aryl-5,6-dihydro-4H-benzo[f][1,2,4]triazolo[1,5-α]azepine derivatives 7 was developed. The synthesis was based on the cycloaddition of the 1,2,3,4-tetrahydronaphthalene a-acetoxy azo compounds 3 with Ar-CN in the presence of AlCl3 and the consecutive ring enlargement.     

New routes to the v-triazolo[1,5-a]pyridine and pyrazolo[1,5-a]pyridine ring systems

New routes to the v-triazolo[1,5-a]pyridine and pyrazolo[1,5-a]pyridine ring systems are described. Treatment of the N-amine salts of 2-picolinealdehyde oxime or 2-pyridyl ketone oximes with polyphosphoric acid gave v-triazolo[1,5-a]pyridines in fair yields. Treatment of 2-picolyl ketones or their oximes with O-mesitylenesulfonylhydroxylamine produced directly pyrazolo-[1,5-a]pyridines. These reactions were extended to the quinoline cases.     

Imine-enamine tautomerism of dihydroazolopyrimidines. 6. Synthesis and tautomerism of thienyl derivatives of dihydro-1,2,4-triazolo-[1,5-a]pyrimidines

The cyclocondensation of thiophene analogs of chalcone with 3-amino-1,2,4-triazole gives 5- and 7-(α-thienyl)dihydro-1,2,4-triazolo[1,5-a]pyrimidines. The tautomer composition of synthesized compounds was analyzed. For communication 5, see [1]. Kharkov State University, 310077 Kharkov, Ukraine, Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 678–682, May, 1999.     

2-Pyridylnitrene from tetrazolo[1,5-a]pyridine and pyrido[2,3-a][1,2,4]oxadiazol-2-one

Flash vacuum thermolyses of tetrazolo[1,5- a]pyridine and pyrido[2,3- a][1,2,4]oxadiazol-2-one generate 2-pyridylnitrene, which was detected by Ar matrix ESR spectroscopy. The thermolysis products are 2-aminopyridine, Z- and E-glutacononitriles, and 2- and 3-cyanopyrroles. The products are formed in the same ratios from the two precursors.     

A new synthesis of thes-triazolo[1,5-a]pyridine ring system

Summary A novel and efficient synthesis ofs-triazolo[1,5-a]pyridines was elaborated by reacting 1,2-diaminopyridinium salts with aldehydes.Dedicated to Prof.F. Sauter on the occasion of his 65^th birthday     

2-aryl(hetaryl)-4H-[1,2,4]triazolo[1,5-a]benzimidazoles

2-(4-Methylphenyl)-4H-[1,2,4]triazolo[1,5-a]benzimidazole and its previously unknown 2-(2-furyl)- and 2-(2-thienyl)-substituted analogs were synthesized by cyclization of benzimidazole-1,2-diamine with the corresponding carboxylic acid chlorides. The IR, ¹H, ¹³C, and ¹⁵N NMR, and mass spectra of the cyclization products in combination with the results of quantum-chemical calculations of NMR chemical shifts showed radical differences of [1,2,4]triazolo[1,5-a]benzimidazoles having no substituent on N⁴ from the recently reported low-melting products of oxidation of 2-amino-1-arylmethylideneaminobenzimidazoles with (diacetoxy-λ³-iodanyl)benzene, which, as we believe, were erroneously assigned analogous structure.