Facile synthesis of 6-hetaryl[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazoles and 7-hetaryl[1,3,4]thiadiazolo[2,3-<Emphasis Type="Italic">c</Emphasis>][1,2,4]triazines with fungicidal activity

Condensation of 4-amino-4H-1,2,4-triazole-3-thiol and 4-amino-6-methyl-3-sulfanyl-1,2,4-triazin-5(4H)-one with ethyl cyanoacetate gave ethyl [1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-ylacetate and ethyl 3-methyl-4-oxo-4H-[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-7-ylacetate, respectively. Reactions of the condensation products with 1,3-diphenylprop-2-en-1-one, aromatic aldehydes, and carbon disulfide or N,N-dimethylformamide dimethyl acetal (followed by treatment with hydrazine hydrate) gave the corresponding 6-hetaryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles and 7-hetaryl-3-methyl-4H-[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-4-ones. Preliminary tests revealed fungicidal activity of the pyrazolyl-substituted derivatives. Published in Russian in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 12, pp. 1813–1818. The text was submitted by the authors in English.     

Reaction of 2-Aryl-5-R-5,6-dihydro-7H-[1,2,4]-triazolo[5,1-<Emphasis Type="Italic">b</Emphasis>][1,3]thiazin-7-ones with Aryl Bromomethyl Ketones and Benzyl Bromide

The products of the reaction of 2-aryl-5-R-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones with aryl bromomethyl ketones are 2-aryl-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones and aryl methyl ketones or 2,5-diaryl[1,3]thiazolo[3,2-b][1,2,4]triazoles and 3-phenyl-2-propenoic acid, depending on the structure of R. The reaction of 2-aryl-5-R-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones with benzyl bromide yields 5-aryl-3-benzylthio-4H-1,2,4-triazoles and 3-aryl-2-propenoyl bromide. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 905–909, June, 2005.     

Synthesis of pyrazolo[4,3-<Emphasis Type="Italic">e</Emphasis>][1,2,4]triazolo[4,3-<Emphasis Type="Italic">c</Emphasis>]pyrimidines

Starting from 1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-ones, a synthesis pathway to the tricyclic pyrazolo[4,3-e][1,2,4]triazolo[4,3-c]pyrimidines is described. Reaction of 1,5-dihydro-4H-pyrazolo[3,4-d] pyrimidin-4-ones with phosphoryl chloride afforded the corresponding 4-chloro-1H-pyrazolo[3,4-d]pyrimidines. Treatment of these compounds with hydrazine hydrate at reflux temperature gave the hydrazino derivatives, which were subsequently cyclized to the titled compounds on heating with orthoesters in ethanol. Correspondence: Abolghasem Davoodnia, Department of Chemistry, School of Sciences, Islamic Azad University, Mashhad Branch, Mashhad 91735-413, Iran.     

Synthesis of heterocycles based on arylation products of unsaturated compounds: XVII. Arylation of 2-acetylfuran and synthesis of 3-R-6-(5-aryl-2-furyl)-7<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazines

Reaction of 2-acetylfuran with arenediazonium chlorides under Meerwein reaction conditions led to the formation of 5-aryl-2-acetylfurans. The bromination of these compounds gave 2-bromo-1-(5-aryl-2-furyl)-ethanones that reacted with 4-amino-4H-5-R-1,2,4-triazole-3-thiols to form 3-R-6-(5-aryl-2-furyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines.     

Synthesis of arylamino-substituted pyrazolo[3,4-d][1,2,4]triazolo[4,3-a]pyrimidinones,pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinones,and their thermal isomerization

The reaction of 1-(4-oxo-1-R-5H-pyrazolo[3,4-d]pyrimidin-6-yl)-4-arylthiosemicarbazides with methyl iodide gave rise to 1,2,4-triazolo-pyrazolopyrimidinones of linear structure, and with dicyclohexylcarbodiimide the products had angular and linear structure. The heating of compounds obtained higher than their melting point resulted in their isomerization into 7-aryl-amino-1-R-1,8-dihydro-4H-pyrazolo[3,4-d]-[1,2,4]triazolo[1,5-a]pyrimidin-4-ones.     

Azines and azoles: CXXVII. 5-phenyl-7<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazolo[5,1-<Emphasis Type="Italic">b</Emphasis>][1,3]thiazin-7-ones: Synthesis and structure

Reactions of 1-acylthiosemicarbazides with methyl 3-phenylprop-2-ynoate provide a new one-step procedure for the synthesis of 2-substituted 5-phenyl-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones. The product structure was determined on the basis of scalar spin-spin coupling constants ² J(¹H-¹⁵N) and ³ J(¹H-¹⁵N) in the ¹H and ¹⁵N NMR spectra and was proved by X-ray analysis. Methyl 3-phenylprop-2-ynoate reacted with 1-acetylthiosemicarbazide in ethanol in the presence of H₂SO₄ to give 3-methyl-7-phenyl[1,2,4]triazolo[3,4-b]-[1,3]thiazin-5-one as the only product.     

A facile one-pot synthesis of 6,7,8,9-tetrahydrobenzo[4,5]thieno[2,3-<Emphasis Type="Italic">d</Emphasis>]-1,2,4-triazolo[4,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidin-5-ones

Abstract  The reaction of 2-mercapto-6,7,8,9-tetrahydro-3H-benzo[4,5]thieno[2,3-d]pyrimidin-4-one or its 2-methylthio derivative with hydrazonoyl halides, in the presence of triethylamine, yielded 6,7,8,9-tetrahydrobenzo[4,5]thieno[2,3-d]-1,2,4-triazolo[4,5-a]pyrimidin-5-ones. The structure of the latter compounds was further confirmed by reaction of 2-mercapto-6,7,8,9-tetrahydro-3H-benzo[4,5]thieno[2,3-d]pyrimidin-4-one with the appropriate active chloromethylenes followed by coupling of the products with benzenediazonium chloride to afford the non-isolable azo-coupling products which converted, in situ, to 6,7,8,9-tetrahydrobenzo[4,5]thieno[2,3-d]-1,2,4-triazolo[4,5-a]pyrimidin-5-ones. The reaction mechanism was proposed and the products were screened for their biological activity. Some of the newly synthesized compounds had a moderate effect against some bacterial and fungal species. Graphical abstract        

Fused polycyclic nitrogen-containing heterocycles: IX. Synthesis and molecular structure of methyl 3-(2-R-5-phenylthiazol-4-yl)-7-phenyl-7<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazolo-[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazine-6-carboxylates

4-Amino-3-(2-R-5-phenylthiazol-4-yl)-1,2,4-triazole-5-thiones react with methyl 3-chloro-2-oxo-3-phenylpropionate to give methyl 3-(2-R-5-phenylthiazol-4-yl)-7-phenyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-6-carboxylates. According to the X-ray diffraction data, the thiazole ring in the products is planar, while the thiadiazine ring has a distorted unsymmetrical boat conformation. Depending on the substituent in the thiazole ring, methyl 3-(2-R-5-phenylthiazol-4-yl)-7-phenyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-6-carboxylates in crystal give rise to different supramolecular structures, lamellar and cylindrical.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 9, 2004, pp. 1358–1365.Original Russian Text Copyright © 2004 by Mamedov, Mustakimova, Gubaidullin, Litvinov, Levin.     

Synthesis of new fluorine-containing pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridinones as promising drug precursors

Methods for the synthesis of 4-R-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones (R = CF₂SAr and 4-CFHSAr) were developed. The derivatives with R = CF₂SAr were obtained by both heterocyclization of 1-substituted 5-aminopyrazoles with ethyl 4,4-difluoro-3-oxo-4-phenylsulfanylbutanoate and replacement of the Br atom in 4-bromodifluoromethyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones by sodium arenethiolates. The fragment 4-CF-HSAr was introduced by replacement of the Cl atom in 4-chlorofluoromethyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones by sodium arenethiolates. Oxidation of 4-CF₂SPh-6,7-dihydro-1H-pyrazolo[3,4-b]pyridin-6-ones gave the corresponding sulfoxides; their structures were confirmed by X-ray diffraction data.     

Synthesis of novel 2-phenoxybenzo[<Emphasis Type="Italic">g</Emphasis>][1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]quinazoline and its derivatives starting with diphenyl-<Emphasis Type="Italic">N</Emphasis>-cyanoimidocarbonate

Cyclocondensation reaction of 3-hydrazinyl-2-naphthoic acid with diphenyl-N-cyanoimidocarbonate furnished the target 2-phenoxy-benzo[g][1,2,4]triazolo[1,5-a]quinazolin-5(4H)-one (1) in high yield. Alkylation, thionation and chlorination of the lactam group in the compound 1 produced a variety of derivatives 2–17. Their structures were characterized by NMR and HREI-MS analyses.     

Synthesis of azepino[1,2-<Emphasis Type="Italic">a</Emphasis>]benzimidazoles and imidazo[1,2-<Emphasis Type="Italic">a</Emphasis>]azepines

Fusion of 4-bromo-1,3-diphenyl-2-buten-1-ones (γ-bromodypnones) with 1,2-dimethyl-1H-benzimidazole and further treatment of the reaction product with a base (morpholine) gives 7,9-diaryl-5-methyl5,10-dihydroazepino[1,2-a]benzimidazol-11-ium bromides. The reaction of γ-bromodypnone with 1-alkyl-2-methyl-1H-imidazoles in benzene at 25 °C gives quaternary azolium salts. Upon heating their solutions in alcohol in the presence of K₂CO₃ the latter cyclize to 1-R-6,8-diaryl-1,5-dihydroimidazo[1,2-a]azepin-4-ium bromides or 1-R-6,8-diaryl-1H-imidazo[1,2-a]azepines depending on the nature of the substituent in the benzene rings and the substituent at the N(1) atom of the imidazole.     

Cyclocondensation of <Emphasis Type="Italic">N</Emphasis>-aryl-3-oxobutanethioamides with 1<Emphasis Type="Italic">H</Emphasis>-1,2,4-triazol-5-amine

Reactions of N-aryl-3-oxobutanethioamides with 1H-1,2,4-triazole-5-amine give mixtures of 7-arylamino-5-methyl[1,2,4]triazolo[1,5-a]pyrimidines, 5-methyl-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidine-7-thione, 7-methyl-4,5-dihydro[1,2,4]triazolo[1,5-a]pyrimidine-5-thione, and 5-arylamino-7-methyl[1,2,4]triazolo[ 1,5-a]pyrimidines whose ratio depends on the substituent in the aryl group of initial N-aryl-3-oxobutanethioamide and solvent nature (the presence of a proton-donor solvent).     

Synthesis and Chemical Transformations of 5-Alkyl(phenyl)-4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidin-7-oles

5,5,7-Trimethyl-4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-a]pyrimidin-7-ol was synthesized by cyclocondensation of 3-amino-1,2,4-triazole with 4-methylpent-3-en-2-one; its chemical transformations, and also the transformations of 5-phenyl-4,5,6,7-tetrahydro[1,2,4]triazolo[1,5-a]pyrimidin-7-ol were investigated in reactions with reagents of diverse electronic nature.     

Synthesis of 8,8-R,R-8,9-dihydro[1,2,4]triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]quinazolin-6(7<Emphasis Type="Italic">H</Emphasis>)-ones

Three-component condensation of 3-amino-1,2,4-triazole (or its 5-methyl and 5-methylthio derivatives), dimedone (or cyclohexane-1,3-dione), and dimethylformamide dimethyl acetal afforded 8,8-R, R-8,9-dihydro[1,2,4]triazolo[1,5-a]quinazolin-6(7H)-ones. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2805–2807, December, 2005.     

Reactions of 1,3-Dialkyl-5-amino-1,3-dihydro-2<Emphasis Type="Italic">H</Emphasis>-imidazo-[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-2-ones with acetylacetone and ethyl acetoacetate

1,3-Dialkyl-5-amino-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones reacted with acetylacetone to give the corresponding 4-(1,3-dialkyl-2-oxo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-5-ylamino)pent-3-en-2-ones which underwent intramolecular cyclization to 1,3-dialkyl-5,7-dimethyl-1,3-dihydro-2H-imidazo[4,5-b]-[1,8]naphthyridin-2-ones on heating in polyphosphoric acid or diphenyl ether. Analogous reaction of 1,3-dialkyl-5-amino-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones with ethyl acetoacetate led to the formation of ethyl 3-(1,3-dialkyl-2-oxo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-5-ylamino)but-2-enoates whose cyclization afforded 1,3-dialkyl-8-hydroxy-7-methyl-1,3-dihydro-2H-imidazo[5,4-b][1,8]naphthyridin-2-ones.     

2-R-7-methyl[1,2,4]triazolo[2,3-a]pyrimidines: synthesis and structures

Reactions of 5-R-3-amino-1,2,4-triazoles with ethoxymethylideneacetylacetone and ethyl ethoxymethylideneacetoacetate proceeded regioselectively, giving 2-R-7-methyl[1,2,4]triazolo[2,3-a]-pyrimidines in good yields. The compounds obtained were characterized by elemental analysis, ¹H NMR spectroscopy, and X-ray diffraction analysis (for ethyl 2-ethylthio-7-methyl[1,2,4]triazolo[2,3-a]pyrimidine-6-carboxylate). The frontier orbitals, the molecular electrostatic potential, and the geometries of the reagent molecules were calculated by the DFT method (B3LYP/6-31G**). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1244–1248, June, 2008.     

Synthesis of substituted 4-([1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]-[1,3,4]thiadiazol-6-yl)quinolines

4-Amino-5-R¹-4H-1,2,4-triazole-3-thiols react with 2-R²-6-R³-quinoline-4-carboxylic acids in phosphoryl chloride to give 2-R²-6-R³-4-(3-R¹-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-yl)quinolines.     

Regioselectivity of cyclization of 3-allyl(propargyl)sulfanyl-5<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazino[5,6-<Emphasis Type="Italic">b</Emphasis>]indoles

The interaction of 3-allylsulfanyl-5H-[1,2,4]triazino[5,6-b]indole with iodine led to 1-iodomethyl-1,2-dihydro[1,3]thiazolo[2',3':3,4][1,2,4]triazino[5,6-b]indol-11-ium pentaiodide with an angular structure, on the basis of which 1-iodomethyl-1,2-dihydro[1,3]thiazolo-, 1-methylidene-1,2-di-hydro[1,3]thiazolo, and 1-methyl[1,3]thiazolo derivatives were obtained. The intramolecular cyclization of 3-propargyl(allyl)sulfanyl-5H-[1,2,4]triazino[5,6-b]indoles under the influence of concentrated sulfuric acid led to linear annelated products:3-methyl[1,3]thiazolo[3',2':2,3][1,2,4]tri-azino[5,6-b]indole or its 2,3-dihydro derivative.     

2-R-5-Ar(Het)-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones

A novel method for synthesis of 2-R-5-Ar(Het)-5,6-dihydro-7H-[1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones by condensation of 3-R-4,5-dihydro-1H-1,2,4-triazole-5-thiones with 3-aryl(heteryl)-2-propenoyl chlorides is proposed.     

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.