Novel One-Pot Multicomponent Synthesis of Substituted 2,3-Dihydro-2-(6-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-3-yl)phthalazine-1,4-diones and Substituted 3-[3-(N′-Benzylidene-hydrazino)-7H-[1,2,4] triazolo[3,4-b][1,3,4]thiadiazin-6-yl]-4-hydroxy-6-methyl-pyran-2-ones

A one-pot procedure has been developed for the synthesis of substituted 2,3-dihydro-2-(6-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7H-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazin-3-yl)phthalazine-1,4-diones by reaction of 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, 4-amino-5-hydrazino-4H-[1,2,4]triazole-3-thiol, and phthalic anhydrides in acetic acid medium. Similarly, a one-pot, three-component synthetic procedure has been developed for substituted 3-[3-(N¹-benzylidene-hydrazino)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl]-4-hydroxy-6-methyl-pyran-2-ones from 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, 4-amino-5-hydrazino-4H-[1,2,4]triazole-3-thiol, and various aromatic aldehydes in absolute ethanol and a few drops of glacial acetic acid.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Synthesis, structure and properties of N-acetylated derivatives of methyl 5-amino-1H-[1,2,4]triazole-3-carboxylate

Methyl 5-amino-1H-[1,2,4]triazole-3-carboxylate hydrochloride (1). and free ester (2). were obtained and 2 was reacted with Ac(2)O to give the acetylated products 3-6. Compounds 1-6 were studied using HPLC, GC-MS, FTIR and multinuclear NMR spectroscopy, including the cross-polarisation magic angle spinning (CPMAS) technique. The results of the acetylation of 2 were compared to those of the acetylation of 5-amino-1H-[1,2,4]triazole, and for 2 a significant decrease in the susceptibility to acetylation was found. The reaction of 2 with Ac(2)O at 20 degrees C, regardless of the amount and the concentration of the latter, including neat Ac(2)O, proceeds fully regioselectively and leads to one product: methyl 1-acetyl-5-amino-1H-[1,2,4]triazole-3-carboxylate (3). In sharp contrast to 5-amino-1H-[1,2,4]triazole, neither an additional monoacetylated isomer, whether annular or exocyclic, nor any diacetylated derivative could be detected. The diacetylation of 2 requires the process to be carried out in neat boiling Ac(2)O and, as in the case of 5-amino-1H-[1,2,4]triazole, gives two diacetylated isomers. These are methyl 1-acetyl-3-(acetylamino)-1H-[1,2,4]triazole-5-carboxylate (4) and 1-acetyl-5-(acetylamino)-1H-[1,2,4]triazole-3-carboxylate (5). Hypothetical pathways of their formation have been suggested. A mixture of 4 and 5 upon hydrolysis of the ring acetyl group gives the monoacetylated derivative methyl 5-(acetylamino)-1H-[1,2,4]triazole-3-carboxylate (6). The spectroscopic, structural and conformational characteristics of compounds 1-6 have been given and methods for their preparation have been provided.     

Novel one-pot multicomponent synthesis of (E)-2-(benzylideneamino)-5-mercapto-4H-1,2,4-triazol-3-yl)-2,3-dihydrophthalazine-1,4-dione derivatives

Abstract

An expeditious, one-pot multicomponent reaction has been developed for the synthesis of (E)-2-(benzylideneamino)-5-mercapto-4H-1,2,4-triazol-3-yl)-2,3-dihydrophthalazine-1,4-dione derivatives. Condensation of 4-amino-5-hydrazino-4H-1,2,4-triazole-3-thiol with phthalic anhydride and aromatic aldehyde afforded the (E)-2-(benzylideneamino)-5-mercapto-4H-1,2,4-triazol-3-yl)-2,3-dihydrophthalazine-1,4-diones in acetic acid medium with excellent yields. All the synthesized compounds were characterized by their analytical and spectral data.     

A facile one-pot three-component synthesis of benzylideneamino-3,5-dimethyl-1H-pyrazoles

A facile, one-pot three-component protocol for the synthesis of substituted 4-(benzylideneamino)-5-(3,5-dimethyl-1H-pyrazol-1-yl)-4H-1,2,4-triazole-3-thiols have been reported by the reaction of 4-amino-5-hydrazinyl-4H-1,2,4-triazole-3-thiol with acetyl acetone and various substituted benzaldehydes via multi component reaction. The newly synthesized derivatives were characterized by their elemental analysis and spectral data. The current strategy provides heterocyclic compounds in good yields with broad substrate scope.     

The efficient synthesis of 3-[6-(substituted)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-3-yl]-1H-indazole

This study presents an efficient synthesis of 3-[6-(substituted-phenyl)-[1,2,4]triazolo[3,4-b][1,3,4] thiadiazol-3-yl]-1H-indazole via dehydrative condensation with cyclization of 4-amino-5-(1H-indazol-3-yl)-4H-[1,2,4]triazole-3-thiol and fluorinated or nonfluorinated carboxylic acids in presence of phosphorous oxychloride. The multistep reaction pathway proceeds through different compounds. Present synthesis has the advantages of easily accessible starting materials, convenient synthesis, simple reaction condition, wider substrate scope, and higher yield (75% to 90% isolated).     

Preparation of aminotriazole-thione derivatives from n-aryl-n-carboxyethyl-β-alanines

Depending on the substituents in the aryl moiety, the fusion of N-aryl-N-ethoxycarbonyl-β-alanines with thiocarbohydrazide gives di- or monotriazole derivatives, namely, 4-amino-(2-{[2-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)ethyl]anilino}ethyl)-4,5-dihydro-1H-1,2,4-triazole-5-thiones, 1-[2-(4-amino- 5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)ethyl]-2,3-dihydroquinolin-4(1H)-ones, 4-amino-3-[2-(4-methylanilino))ethyl]-4,5-dihydro-1H-1,2,4-triazole-5-thione and 4-amino-3-[2-(4-ethoxyanilino)-ethyl]-4,5-dihydro-1H-1,2,4-triazole-5-thione. A ditriazolethione derivative was also obtained from the diethyl ester of N-ethoxycarbonyl-N-(4-ethoxyphenyl)- β-alanine.     

Synthesis of azoles from 3-[(3-hydrazino-3-oxopropyl)anilino]-and 3-[(3-hydrazino-3-oxopropyl)-4-methylanilino]propane hydrazides

Condensation of 3-[(3-hydrazino-3-oxopropyl)anilino]-and 3-[(3-hydrazino-3-oxopropyl)-4-methylanilino]propane hydrazides with 2,4-pentanedione, phenyl isocyanate or phenyl isothiocyanate (with subsequent work up of the semicarbazides obtained by base), and carbon disulfide gave respectively: 1-(3,5-dimethyl-1H-1-pyrazolyl)-3-[3-(3,5-dimethyl-1H-1-pyrazolyl)-3-oxopropylanilino]-1-propanone, 3-(2-{[2-(5-oxo-4-phenyl-4,5-dihydro-1H-1,2,4-triazol-3-yl)ethyl]anilino}ethyl)-4-phenyl-4,5-dihydro-1H-1,2,4-triazol-5-one and its thio analog, and 5-(2-{[2-(2-thioxo-2,3-dihydro-1,3,4-oxadiazol-5-yl)ethyl]anilino}ethyl)-2,3-dihydro-1,3,4-oxadiazole-2(3H)-thione plus their methyl derivatives. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1353–1358, September, 2007.     

Synthesis and study of heteroaromatic ligands containing a pyrimidine ring

5-Hexyl-3-[2-(1H-pyrazol-1-yl)pyrimidin-4-yl]amino-1(2)H-1,2,4-triazoles and 2-(3,5-dipropyl-4-ethyl-1H-pyrazol-1-yl)-6-methyl-4-(5-methyl-1H-pyrazol-1-yl)-aminopyrimidine were synthesized by the reaction of 4-chloropyrimidines with 3-araino-5-hexyl-1H-1,2,4-triazole and 3-amino-5-methyl-1H-pyrazole. Their IR, UV, and PMR spectra were investigated. New methods for the preparation of the intermediates, viz., 2-hydrazino-4(3H)-pyrimidinones and 2-(1H-pyrazol-1-yl)-4(3H)-pyrimidinones, that make it possible to obtain these compounds in higher yields are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1673–1677, December, 1980.     

Synthetic routes towards tetrazolium and triazolium dinitromethylides

Tetrazolium-5-dinitromethylide sodium salt has been prepared (91%) by cyclization of 1-amino-1-hydrazino-2,2-dinitroethene with nitrous acid in water. 5-Imino-1-(hydroxyiminonitromethyl) derivatives were obtained by nitration of 2-(5-amino-1,3-dimethyl-1H-1,2,4-triazol-4-ium-4-yl)- and 2-(5-amino-4-methyl-1H-tetrazolium-1-yl)acetate complex salts. Treatment of 4-methyl-1-(2-oxopropyl)-1-tetrazolium methylsulfate with nitric and sulfuric acid gave methyl (3-nitro-1,2,4-oxadiazol-5-yl)amine (27%) probably via dinitromethylide followed by cyclization and loss of nitrogen.__________Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 127–134, January, 2005.     

The use of umbelliferone in the synthesis of new heterocyclic compounds

New coumarin derivatives, namely 7-[(5-amino-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one, 5-[(2-oxo-2H-chromen-7-yloxy)methyl]-1,3,4-thiadiazol-2(3H)-one, 2-[2-(2-oxo-2H-chromen-7-yloxy)acetyl]-N-phenylhydrazinecarbothioamide, 7-[(5-(phenylamino)-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one and 7-[(5-mercapto-4-phenyl-4H-1,2,4-triazol-3-yl)methoxy]-2H-chromen-2-one were prepared starting from the natural compound umbelliferone. The newly synthesized compounds were characterized by elemental analysis and spectral studies (IR, 1H-NMR and 13C-NMR).     

Corrosion inhibitive properties and electrochemical adsorption behaviour of some piperidine derivatives on brass in natural sea water

The piperidine derivatives, namely (4-Hydrazono-2,6-diphenyl-piperidin-1-yl)-ethanoic acid hydrazide; 5-(2,6-diphenyl-4-hydrazono-piperidin-1-ylmethyl)-3H-[1, 3, 4]oxadiazole-2-thione; 4-amino-5-(2,6-diphenyl-4-hydrazono-piperidin-1-ylmethyl)-4H-[1, 2, 4]triazole-3-thiol were synthesised and characterised by Fourier transform-infrared spectroscopic studies to confirm the purity of compounds. The corrosion inhibition effect of these compounds on brass in natural sea water was studied using potentiodynamic polarisation studies and electrochemical impedance spectroscopic measurements. The presence of these inhibitors in sea water suppresses both anodic and cathodic processes, and it is enhanced by the increase in the concentration of the inhibitors. The surface morphology of the brass after its exposure to natural sea water with and without inhibitors was examined by scanning electron microscopy. Inductively Coupled Plasma Atomic Emission Spectroscopic analysis were carried out after the polarisation studies showed minimum leached out of metal ions from the brass specimen in the presence of inhibitors. The structural and electronic parameters of these piperidine derivatives were calculated using computational methodologies.     

Ultrasound-assisted,one-pot,three-component synthesis and antibacterial activities of novel indole derivatives containing 1,3,4-oxadiazole and 1,2,4-triazole moieties

Thirteen novel indole derivatives were efficiently synthesized through ultrasound irradiation by using 4-amino-5-(1H-indol-3-yl)-4H-[1,2,4]triazole-3-thiol (8) and 2-mercapto-5-substituted-1,3,4-oxadiazoles (5a–m). Compared with conventional and microwave methods, yields increased to 82–93%, and reaction times decreased to 15–35 min. The structures of these novel compounds were characterized by spectral data and elemental analysis. Two out of the synthesized compounds (10f and 10l) exhibited excellent activity against Staphylococcus aureus and Escherichia coli, and thus warrant further research.     

Synthesis of 4(pyrazol-3-yl)[1,2,4]triazolo[4,3-a]quinoxalines and tetrazolo analog

The transformation of 2-chloro-3-[5-(acetoxymethyl)-1-phenylpyrazol-3-yl]quinoxaline 3 to 1-aryl-4-[5-(hydroxymethyl-1-phenylpyrazol-3-yl][1,2,4]triazolo[4,3-a]quinoxalines 4a-c has been achieved upon treatment with aroylhydrazines in boiling butanol. Compounds 4a-c were smoothly acetylated by acetic anhydride to give their acetyl derivatives 5a-c in good yield. 4-[5-(Acetoxymethyl)-1-phenylpyrazol-3-yl]-1-methyl[1,2,4]triazolo[4,3-a]quinoxaline was prepared by ring closure of 2-hydrazino-3-[5-(hydroxymethyl)-1-phenylpyrazol-3-yl]quinoxaline 6 by the action of acetic anhydride. The reaction of 6 with acetylacetone afforded 3-[5-(hydroxymethyl)-1-phenylpyrazol-3-yl]-2-(3,5-dimethylpyrazol-1-yl)quinoxaline 8 . In addition, the reaction of 3 with sodium azide in boiling N, N-dimethylformamide yielded the fused tetrazolo[1,5-a]quinoxaline 9 .     

Synthesis and study of 3-(pyrimidin-2-yl)amino-1(2)H-1,2,4-triazole derivatives

The previously unknown 3-[4(3H)-pyrimidinon-2-yl]amino-1H-1,2,4-triazoles, which were converted to 3-[4-chloro-, 3-(4-ethoxy)-, 3-(4-hydrazinopyrimidin-2-yl)]-amino-2(4)H-1,2,4-triazoles, were obtained by the reaction of 2-nitroamino-4(3H)-pyrimidinones with 3-amino-5-hexyl-1H-1,2,4-triazole. The condensation of the initial products with -diketones gave 3-[4-(1H-pyrazol-1-yl)pyrimidin-2-yl]-amino-2(4)H-1,2,4-triazoles. The IR, UV, and PMR spectra of the synthesized compounds were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1678–1681, December, 1980.     

5-Furan-2yl[1,3,4]oxadiazole-2-thiol, 5-furan-2yl-4H [1,2,4] triazole-3-thiol and their thiol-thione tautomerism

5-Furan-2-yl[1,3,4]oxadiazole-2-thiol (Ia) and 5-furan-2-yl-4H-[1,2,4]-triazole-3-thiol (Ib) were synthesized from furan-2-carboxylic acid hydrazide. Mannich bases and methyl derivatives were then prepared. The structures of the synthesized compounds were confirmed by elemental analyses, IR and (1)H-NMR spectra. Their thiol-thione tautomeric equilibrium is described.     

Synthesis of new bis-1,2,4-triazole derivatives

A series of new 1,2/1,3-bis[o-(N-methylidenamino-3-aryl-5-phenyl-4H-1,2,4-triazole-4-yl)phenoxy]ethane/propane derivatives 4 were prepared in good yields by treatment of 4-amino-3-aryl-5-phenyl-4H-1,2,4-triazoles 2 with certain bis-aldehydes 1.Compounds 4 were reduced with NaBH(4) to afford the corresponding 1,2/1,3-bis[o-(N-methylamino-3-aryl-5-phenyl-4H-1,2,4-triazole-4-yl)phenoxy]ethane/propane derivatives 5. All new compounds were characterized by IR, (1)H-NMR, (13)C-NMR and mass spectral data.     

An Efficient Synthesis of 1,5-Thiadiazepines and 1,5-Benzodiazepines by Microwave-Assisted Heterocyclization

A novel and efficient method for the synthesis of substituted thiazepines and diazepines has been developed. A simple one-pot reaction of chalcones 1a–f with 1-amino-2-mercapto-5-phenyl-1,3,4-triazole and o-phenylenediamine in the presence of a catalytic amount of sodium acetate under microwave irradiation gave 2-(3,8-diphenyl-7,8-dihydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepin-6-yl)phenoles 2a–f and 2-(2-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)phenoles 3a–f, respectively. The structure of all the synthesized compounds was elucidated on the basis of elemental analysis, IR, ¹H and ¹³C NMR, and mass spectral data.     

Synthesis and biological activity of some novel derivatives of 4-amino-3-(D-galactopentitol-1-yl)-5-mercapto-1,2,4-triazole

To discover new 1,2,4-triazole derivatives which may possess significant biological activities, we synthesized a series of novel 6-aryl-3-(D-galactopentitol-1-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines and 4-(arylmethylidene)amino-5-(D-galactopentitol-1-yl)-3-mercapto-4H-1,2,4-triazoles from 4-amino-3-(D-galactopentitol-1-yl)-5-mercapto-1,2,4-triazole. All the title compounds were characterized by elemental analysis, IR, 1H- and 13C-NMR. Plant growth-regulating activity tests showed that these compounds have remarkable effects on the growth of radish and wheat.     

Synthesis of Some 3-Substituted 1,2-Dihydroindoles

The reaction of 4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6-methyl carboxylate 2 with hydrazine hydrate in methanol gave 4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6-carbonylhydrazine 3. Furthermore, the reaction of 3 with carbon disulfide and then hydrazine hydrate afforded 3-[6-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-4-oxo-1,3-thiazin-2-yl] hydrazone-1,3-dihydroindol-2-one 5. the latest reacted with DMAD to give {6-hydroxy-3-[4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6yl]-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-7-ylidene}methoxycarbonylmethylene 6.     

Synthesis,characterization and biological activity of Hg(II), Fe(III) complexes with 1,3,4-oxadiazole, 1,2,4-triazole derivatives from L-methionine

Four novel heterocyclic1,3,4-oxadiazole, 1,2,4-triazole derivatives, namely: 5-[1-amino-3-(methylsulfanyl)propyl]-1,3,4-oxadiazole-2(3H)-thione (4), 4-amino-5-[1-amino-3-(methylsulfanyl)propyl]-4H-1,2,4-triazole-3-thiol (5), 1-amino-3-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-5-thiol (7), and 5-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-3-thiol (9) have been synthesized from l-methionine and characterized by different spectroscopic techniques (FT-IR, UV–Vis, ¹H NMR, ¹³C NMR and MS). Complex formation with Hg⁺⁺ and Fe⁺⁺⁺ ions were formed from the four heterocyclic 4, 5, 7 and 9. The antimicrobial activities for synthetic intermediates and final four products were assisted using paper disk diffusion method against Gram-negative bacteria: Escherichia coli, Pseudomonas aeroginosae and Gram-positive bacteria: Staphylococus aureus 25923, Staphylococus aureus 43300 and showed variant activity against some of the microorganisms tested.