Synthesis and mass-spectrometric study of 2-amino- and 2-chloro-5-aryl-1,3,4-thiadiazoles

The cyclization of aldehyde thiosemicarbazones with ferric chloride yielded 2-amino-5-aryl-1,3,4-thiadiazoles, forming 2-chloro-5-aryl-1,3,4-thiadiazoles in the Sandmeyer reaction. The mass-spectrometric behavior of the 2-amino- and 2-chloro-5-aryl-1,3,4-thiadiazoles was studied; the typical routes of fragmentation characteristic of each group of compounds were found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1416–1419, October, 1986.     

Synthesis ofβ-chloroethylamino derivatives in the 1,3,4-thiadiazole series. I

A study is made of the hydroxyethylation of some 2-amino-5-aryl-1,3,4-thiadiazoles and replacement of the hydroxyl group in the hydroxyethylation products by chlorine, as well as of condensation of p-[di(β-chloroethyl)amino]phenylacetyl chloride with the 2-amino-5-aryl-1,3,4-thiadiazoles.     

Anodic formation of 3,6-diaryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles and 2(3-aryl-5-methyl-1H-[1,2,4]triazol-1-yl)-5-aryl-1,3,4-thiadiazoles

3,6-Disubstituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles together with the unknown systems 2-(3-aryl-5-methyl-1H-[1,2,4]triazol-1-yl)-5-aryl-1,3,4-thiadiazoles were obtained by anodic oxidation, under aprotic conditions, of aryl aldehyde N-(5-aryl-1,3,4-thiadiazol-2-yl) hydrazones. Mechanistic proposals are given.     

Synthesis of 2-amino-5-aryl-1,3,4-thiadiazoles and their condensed analogs with the use of aromatic nitrites

Aromatic nitrites are found to readily react with thiosemicarbazide and 4-amino-3-methyl-1,2,4-triazol-5-thione in a solution of polyphosphoric acid to give corresponding 2-amino-5-aryl-1,3,4-thiadiazoles.     

A convenient and general synthesis of 2-amino-1,3,4-thiadiazoles. Dehydration of acylthiosemicarbazides with methanesulfonic acid

2-Amino-5-alkyl and 2-amino-5-aryl-1,3,4-thiadiazoles were prepared by the dehydration of 2-acylthiosemicarbazides with molar equivalents of methanesulfonic acid in refluxing toluene. The synthesis appears to be general.     

Carbon suboxide and some of its reactions

The reaction of carbon suboxide with a number of 2-amino-1,3,4-thiadiazoles has given the corresponding pyrimido[1,2-b]-1,3,4-thiadiazoles     

3-芳基-6-对甲苯甲酰氨基均三唑并[3,4-b]-1,3,4-噻二唑的合成及生物活性

利用3-芳基-4-氨基-5-巯基-1,2,4-均三唑和对甲苯甲酰异硫氰酸酯在乙腈中反应, 得到一系列3-芳基-6-对甲苯甲酰氨基均三唑并[3,4-b]-1,3,4-噻二唑, 用¹H NMR, IR, MS和元素分析确定了其结构, 并对其进行了抗菌活性测试.     

3-芳基-6-对氯苯甲酰氨基均三唑并[3,4-b]-1,3,4-噻二唑的 合成及生物活性

利用3-芳基-4-氨基-5-巯基-1,2,4-均三唑和对氯苯甲酰异硫氰酸酯在乙腈中反应, 得到一系列3-芳基-6-对氯苯甲酰氨基均三唑并[3,4-b]-1,3,4-噻二唑, 用1H NMR, IR, MS和元素分析确定了其结构, 并对其进行了抑菌活性测试.     

Syntheses of 3-[5-Methyl-1-(4-Methylphenyl)-1,2,3-Triazol-4-yl]-6-Substituted-s-Triazolo[3,4-b]-1,3,4-Thiadiazoles

1,2,3-Triazole derivatives have been reported as inhibiting tumor proliferation, invasion, and metastasis^[1]. The fused l,3,4-triazolo[3,4-b]-1,3,4-thiadiazoles derivatives show various biological effects such as antifungal^[2], antibacterial, hypotensive and CNS depressant activities^[3]. We have reported several 6-aryl-3-[5-methyl-1-(4-methylphenyl)-1,2,3-triazol-4-yl]-s-triazolo[3,4-b]-1,3,4-thiadiazoles in the previous paper^[4]. The novel 6-aryl-3-[5-methyl-1-(4-methylphenyl)-1,2,3-triazol-4-yl]-s-triazolo[2,4-b]-1,3,4-thiadiazoles 6a-j have been synthesized by the condensation of 4-amino-5-mercapto-3-[5-methyl-1-(4-methylphenyl)-1,2,3-triazol-4-yl]-s-triazole 5 with various aromatic carboxylic acids in the presence of phosphorus oxychloride. The mercaptotriazole 5 was prepared from 4,the latter being prepared from 1 throng 2 and 3. The title compounds 6 were depicted in scheme 1. The structures of these compounds were established by elemental analysis, NMR, MS and IR techniques.     

Synthesis of 6-aryl substituted 3-(5''''-phenyl-2H-tetrazole-2''''-methylene)-S-triazolo[3,4-b]-1,3,4-thiadiazoles

In this paper , 10 novel 6-aryl-3-(5'-phenyl-2H-tetrazole-2'-methylene)-S-triazolo[3, 4-b]-1,3,4-thiadiazoles have been synthesized by the condensation of 3-(5'-phenyl-2H-tetrazole-2'-methylene)-4-amino-5-mercapto-1,2,4-triazole with various aromatic carboxylic acids in the presence of phosphorus oxychloride. The structure of these compounds was determined by elemental analysis , UV, IR, 1H NMR and MS. Their spectral properties were also discussed.     

Studies on Condensed Heterocyclic Compounds XVII. Synthesis of 6-(1-Aryl-5-methyl-1,2,3-triazol-4-yl)-3-phenyl-s-triazolo[3,4-b]-1,3,4-thiadiazoles

Treatment of 4-amino-5-mercapto-3-phenyl-1,2,4-triazole 2 with 1-aryl-4-carboxy-5-methyl-1,2,3-triazoles 1a-1j in a one-step reaction yielded several 6-(1-aryl-5-methyl-1,2,3-triazol-4-yl)-3-phenyl-s-triazolo[3,4-b]-1,3,4-thiadiazoles 3a-3j . The structures of all the products were established on the basis of elemental analyses and spectral data. The fragmentation of the mass spectra of 3a-3j under electron impact was discussed.     

Synthesis and antibacterial activities of novel imidazo[2,1-b]-1,3,4-thiadiazoles

2-Amino-5-(2-aryl-2H-1,2,3-triazol-4-yl)-1,3,4-thiadiazoles 2-4 have been synthesized by the reaction of 2-aryl-2H-1,2,3-triazole-4-carboxylic acids 1 with thiosemicarbazide. Their reaction with phenacyl (p-substituted phenacyl) bromides led to formation of the respective 6-aryl-2-(2-aryl-2H-1,2,3-triazol-4-yl)imidazo[2,1-b]-1,3,4-thiadiazoles 5. Reactivity of the latter fused ring towards reaction with different electrophilic reagents afforded the corresponding 5-substituted derivatives 6-8. The structure of the above compounds was confirmed from their spectral characteristics. Some of these compounds were found to possess slight to moderate activity against the microorganisms Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and Escherichia coli.     

Concerning the “synthesis of 2-amino-5-aryl-5H-thiazolo[4,3-b]-1,3,4-thiadiazoles”

Compounds described previously as 2-amino-5-aryl-5H-thiazolo[4,3-b]-1,3,4-thiadiazoles were found to be thiosemicarbazones of aromatic aldehydes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya No. 6, pp. 1228–1229, June, 1997.     

Reactivity of 2-amino-1,3,4-thiadiazoles. Nucleophilic behaviour of some 2-amino-1,3,4-thiadiazoles: Model compounds

The ambident nucleophilic behaviour of some 2-amino-5-H-1,3,4-thiadiazoles in alkylation, acylation and nitrosation reaction has been verified. The structures assigned to the 2-amino-1,3,4-thiadiazoles ( 1a-i ) and to the Δ²-1,3,4-thiadiazolines ( 2a-e ) agree with the spectral data.     

SYNTHESIS OF 2-AROYLAMINO-5-ARYLOXYMETHYL-1,3,4-THIADIAZOLES UNDER LIQUID-LIQUID PHASE TRANSFER CATALYSIS

2-Aroylamino-5-aryloxymethyl-1,3,4-thiadiazoles (I _1–20 ) are synthesized by the condensation of 2-amino-5-aryloxymethyl-1,3,4-thiadiazoles with aroyl chlorides in the presence of PEG-400 phase transfer catalyst.     

Studies on Reactions of 2-Amino-5-Heterocyclyl-1,3,4- -Thia/Oxadiazole with Acylisothiocyanates

It is well known that the addition of acyl isothiocyanate with amine formed 1,3-disubstituted thiourea which possess broad spectrum biological activities, Up till now, the addition of 5-heterocyclyl-2-amino-1,3,4-thia/oxadiazole with acylisothicyanate has not been reported. We wish to describe this reaction in this paper. When the new 2-amino-5-(l-p-chlorophenyl-5-methyl-1,2,3-triazol-4-yl)-1,3,4-thiadiazole (Ⅰ) was reacted with acylisothio-cyanates (Ⅱ), not all the compounds were expected acylthiourea (Ⅲ)^[1,2], some of them were acid amide (Ⅳ). The formation of the products was determined by the substituents of the acylisothiocyanate. In order to investigate the reaction, we synthesized 2-amino-5-aryl-1,3,4-thio/oxadiazole (Ⅴa,b), and then reacted with 1-p-chlorophenyl-5-methyl-1,2,3-triazol-4-formyl-isothiocyanate (Ⅵ). As it was anticipated, the products only were N-(5-aryl-1,3,4-thia/oxadiazol-2-yl)-N'-(1-p-chlorophenyl-5-methyl-1,2,3-triazol-4-formyl) thiourea (Ⅶa,b) (Scheme).     

One-pot synthesis of 2-amino- 5-aryl -5H-thiazolo[4,3-b]-1,3,4-thiadiazoles

Equimolar mixtures of aromatic aldehydes with thioglycolic acid and thiosemicarbazide in H₂SO₄ transform into 2-amino-5-aryl-5H-thiazolo[4,3-b]-1,3,4-thiadiazoles.Translated fromIzvestiya Akademioi Nauk. Seriya Khimicheskaya, No. 3, pp. 763–764, March, 1996.     

Syntheses of Chiral Fused Heterocyclic Compounds Containing l,2,4-Triazole Ring

The chemistry of life is based considerably on chirality. Consequently, stereospecificity has to be regarded as an especially important characteristic of biological systems. The influence of stereospecificity of the biological activities of enzyme inhibitors or compounds binding to receptor is a well known fact in the field of drug action^[1]. s-Triazoles and l,3,4-thiadiazoles are reported to exhibit broad spectrum of biological and pesticidal activities^[2-3].In recent years, bridge head nitrogen heterocycles have received much attention as anthelmintic agents, however, it is not observed that the syntheses of chiral fused heterocyclic compounds containing s-triazoles and l,3,4-thiadiazoles. In order to study the relationship between stereochemistry and the performance of fungicides, we have synthesized a series of (s)-1,2-di(3-aryl-s-triazolo[3,4-b][1,3,4] thiadiazolo-6-yl) ethylamine and (s)-1-(3-aryl-s-triazolo[3,4-b][l,3,4] thiadiazolo-6-yl) ethylamine by the condensation of 3-aryl-4-amino-5-mercapto-1,2,4-triazoles with L-aspartic acid and L-alanine in the presence of phosphorusoxychloride.     

The reaction of N-R-2-cyanothioacetamides with ethyl[(aryl)hydrazono]chloroacetates

Depending on the nature of the substituents in the starting reagents and the basicity of the medium the cyclization of N-R-2-cyanothioacetamides with ethyl [(aryl)hydrazono]chloroacetates gives 3-aryl-2-cyanomethylidene-5-ethoxycarbonyl-1,3,4-thiadiazoles, 5-arylhydrazono-2-cyanomethylidene-3-phenyl-thiazolidin-4-ones, di[(aryl)hydrazono](ethoxycarbonylmethyl) sulfides, and 5-amino-3-cyano-2-phenyl-amino-4-(N-phenylaminothiocarbonyl)thiophene. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp 109–114, January, 2007.