微波促进下3-(2-苯并呋喃基)-4-氨基-5-巯基-1,2,4-三唑

微波辐射条件下, 首先由2-苯并呋喃甲酰肼依次与二硫化碳和水合肼反应合成3-(2-苯并呋喃基)-4-氨基-5-巯基- 1,2,4-三唑, 进一步在微波辐射条件下由4-氨基-5-巯基-1,2,4-三唑分别与芳甲酸/芳氧基乙酸、α-溴代苯乙酮及芳醛反应以较高产率制得了相应的1,2,4-三唑并[3,4-b]-1,3,4-噻二唑、1,2,4-三唑并[3,4-b]-1,3,4-噻二嗪及4-芳亚甲基亚胺基-5-巯基-1,2,4-三唑. 产物结构经IR, ¹H NMR, MS及元素分析进行了表征.     

The Synthesis of Triazolothiadiazines and Thiadiazoles From 1,2-Bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl)- Ethanol and Ethane

The reaction of DL-malic and succinic acids with thiocarbohydrazide afforded 1,2-bis[4-amino-5-mercapto-1,2,4-triazol-3-yl]-ethane derivatives 3a and 3b. The reaction of 3a,b with phenacyl bromide and benzoin afforded 1,2-bis-1,2,4-triazolo [3,4-b][1,3,4]thiadiazine derivatives 4 and 5. The carboethoxymethylation of 3a and 3b gave 6a and 6b, respectively, and their reactions with carbon disulfide and benzoylisothiocyanate gave the 1,2-bis-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole 7 and 9, and with p-nitrobenzaldehyde gave a Schiff's base and dihydrothiadiazole 8. The structures were confirmed by using ¹ H and ¹³ C NMR spectra. Selected members of these compounds were screened for antimicrobial activity.     

Pyridazine Derivatives and Related Compounds,Part 17: 1 The Synthesis of Some 3-Substituted Pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazines and Their Antimicrobial Activity

The reaction of the hydrazide of pyridazino[3′, 4′:3, 4]pyrazolo[5, 1-c]-1,2,4-triazine-3-carboxylic acid 3 with carbon disulfide in the presence of potassium hydroxide gave the 1,3,4-oxadiazole-2-thione derivative 4. The methylation of this product in an alkaline medium proceeds at the sulfur atom. The reaction of 3 with KOH and carbon disulfide followed by addition of hydrazine hydrate afforded the 4-amino-1,2,4-triazole derivative 6. Compound 3, when heated either with ammonium thiocyanate or with potassium thiocyanate, afforded the same product 7, which underwent cyclodehydration in the presence of acetyl chloride, which led to the 2-acetylamino-1,3,4-thiadiazole derivative 8. In a basic medium, the product was 1,2,4-triazole-3-thione derivative 9. The reaction of 3 with phenyl isothiocyanate provided thiosemicarbazide derivative 10, which underwent cyclodehydration in a basic medium and gave the 1,2,4-triazole derivative 11. The reaction of 3 with formic acid yielded the 3-carboxyl-2′-(formyl)hydrazine derivative 12. The refluxing of the latter with phosphorus pentasulfide in xylene yielded compound 14 (65%). The reaction of compound 12 with phosphorus pentoxide afforded compound 15. Some representative examples were screened for antimicrobial activity.     

Synthesis,Reactions, and Characterization of 6-Amino-4-(Benzo[b]Thiophen-2-YL)-2-Thioxo-1, 2-Dihydropyridine-3, 5-Dicarbonitrile

Abstract

Benzothiophene -2- carbaldehyde 1 reacted with 2-cyanoethanethioamide 2 in 1:2 molar ratios to give the corresponding 6-amino-4-(benzo[b]thiophen-2-yl)-2-thioxo-1, 2-dihydropyridine-3,5-dicarbonitrile 6. The synthetic potentiality of compound 6 was investigated via its reaction with active halogen-containing reagents to afford the corresponding thieno[2,3-b]pyridine derivatives 11a,b, 14, 16, and 19. Also, compound 6 reacted with hydrazine hydrate to give the pyrazolo[3,4-b]pyridine derivative 21. Compound 21 condensed with 4-(2-thienyl)benzaldehyde to afford pyrazolo[3,4-b]pyridine derivative 23. Structural elucidation of all the newly synthesized heterocyclic compounds was based on elemental analyses, IR, ¹H NMR, and mass spectra.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis of 3,6-bisubstituted phenyl-bi-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole derivatives

2,5-Bihydrazino-1,3,4-thiadiazole (2) was synthesized by condensation of 2,5-bimercapto-1,3,4-thiadiazole (1) with hydrazine hydrate, and compound 2 reacted with acyl chloride to give 2,5-biacylhydrazino-1,3,4-thiadiazole derivatives (3a–3e). Ring closure of compounds 3a–3e was achieved with POCl3 as the cyclization agent giving 3,6-bisubstituted phenyl-bi-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole derivatives (4a–4e), respectively. The novel compounds were identified by elemental analysis, and by infrared (IR), 1H-nuclear magnetic resonance (NMR), and mass (MS) spectrometry. The mechanism of the cyclization is also discussed. __________ Translated from Organic Chemistry, 2006, 26(12): 1720–1722 [译自: 有机化学]     

1,3-Disubstitutedpyrazole-4-caboxaldehyde in Heterocyclic Synthesis: A Novel Synthesis of Pyridine-2(1H)-thione and Fused Nitrogen and/or Sulfur Heterocyclic Derivatives

Pyridine-2(1H)-thione 5 was synthesized from the reaction of 3-[3-(4-chlorophenyl)-1-phenyl-1H-pyrazol-4-yl]-1-phenylpropenone (3) and cynothioacetamide (4). Compound 5 reacted with halogented compounds 6a–e to give 2-S-alkylpyridine derivatives 7a–e, which could be in turn cyclized into the corresponding thieno[2,3-b]-pyridine derivatives 8a–e. Compound 8a reacted with hydrazine hydrate to give 9. The latter compound reacted with acetic anhydride (10a), formic acid (10b), acetic acid, ethyl acetoacetate, and pentane-2,4-dione to give the corresponding pyrido[3′,2′:4,5]thieno-[3,2-d]pyrimidine 13a,b, pyrazolo[3′,4′:4,5]thieno[3,2-d]pyridine 14 and thieno[2,3-b]-pyridine derivatives 18 and 20, respectively. Alternatively, 8c reacted with 10a,b and nitrous acid to afford the corresponding pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine 24a,b and pyrido[3′,2′:4,5]thieno[3,2-d][1,2,3]triazine 26 derivatives, respectively. Finally compound 5 reacted with methyl iodide to give 2-methylthiopyridine derivative 27, which could be reacted with hydrazine hydrate to yield the corresponding pyrazolo[3,4-b]-pyridine derivative 29.     

Synthesis of Heterocycles via 2-Thioxo-1,2-dihydropyridine-3-carbonitrile Derivative

The present study aimed to investigate the synthetic potentiality and chemical reactivity of 2-thioxo-1,2-dihydropyridine-3-carbonitrile derivative 1. This goal performed via its reaction with each of 1-chloroacetone and iodomethane to afford the corresponding 2-alkylthio derivatives 3 and 9, respectively. Compound 3 underwent intramolecular cyclization to afford the corresponding thieno[2,3-b]pyridine derivative 4 which in turn, reacted with dimethylformamide/dimethylacetal followed by hydrazine hydrate and nitrous acid to afford the corresponding pyridothienopyrimidine and pyridothienopyridazine derivatives 6 and 8, respectively. On the other hand, Compound 9 reacted with hydrazine hydrate to give 3-aminopyrazolo[3,4-b]pyridine derivative 10, which diazotized with nitrous acid to give the corresponding diazonium salt 11. Compound 11 coupled with several active –CH₂-containing reagents to synthesize the corresponding pyridopyrazolo-triazines 15, 24, 29, and 31. The formulas of all newly synthesized heterocyclic compounds were elucidated by considering the data of IR, ¹H NMR, Mass spectral data, as well as data from elemental analyses.     

On the preparation of substituted 4H- 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

The reaction of benzoyl isothiocyanates and methoxycarbonyl isothiocyanate with 4-amino-4,5-dihydro-3-(methylthio)-1,2,4-triazin-5-ones in acetonitrile gave several substituted 4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones VIa-h instead of the expected thioureas. In addition, benzoyl isothiocyanate reacted with 4-amino-3-(methylthio)-5-(trifluoromethyl)-4H-1,2,4-triazole to give the benzoyl thiourea IX and with 4-amino-3-mercapto-5-(trifluoromethyl)-4H-1,2,4-triazole to give the bicyclic compound N-[3-(trifluoromethyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol-6-yl]benzamide IX .     

Thieno[2,3-b]pyridine-2-carbohydrazide in Polyheterocyclic Synthesis: The Synthesis of Pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine,Pyrido[3′,2′:4,5]thieno[3,2-d][1,2,3]triazine,and Pyrazolyl,Oxadiazolylthieno[2,3-b]pyridine Derivatives

Pyrdine-2(1H)-thione 1 reacted with ethyl chloroacetate 2 to give 2-S-ethoxy-carbonylmethylpyridine derivative 3, which could be cyclized into thieno[2,3-b]-pyridine-2-carbohydrazide derivative 5 by boiling with hydrazine hydrate. The latter compound reacted with cinnamonitrile derivatives 6a, b, triethylorthoformate, formic acid, dimethylformamide-dimethylacetal, and diethyl carbonate to give the corresponding shiff base 7a, b and pyrido[3′,2′;-4,5]thieno[3,2-d]pyrimidine derivatives 10–13 in respective manner. On the other hand, compound 5 also reacted with carbondisulphide and phenyl isothiocyanate to afford the corresponding 2-(1,3,4-oxadiazolo-2-yl)thieno[2,3-b]pyridine derivatives 18 and 22. Finally, compound 5 reacted with some β-dicarbonyl compounds, such as ethyl acetoacetate, acetylacetone and ethyl β-arylazoacetoacetate, to yield the corresponding 2-(pyrazol-1-yl-carbonyl)thieno[2,3-b]pyridine derivatives 24, 25, and 27 respectively.     

Stereospecific synthesis of 6,7-dihydro-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines

The reaction of 3-mercapto-4-arylideneamino-1,2,4-triazoles 2b-d , 3a-d with ethyl bromoacetate and/or phenacyl bromide in hot DMF and triethylamine affords the stereochemically pure 7-acyl-6-aryl-6,7-dihydro-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines 4b-d , 5a-d , 6b , d in which the consecutive hydrogen atoms N(5)H-C(6)H-C(7)H are cis to each other. This stereochemistry was determined by ¹H NMR spectroscopy and confirmed by comparison with the spectrum of 3,6-diphenyl-6,7-dihydro-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine 10 . The latter was prepared by NaBH₄ reduction of 3,6-diphenyl-5H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine 9 . The reported reactions offer two interesting stereospecific syntheses of the condensed heterocyclic compounds.     

3,6-二取代苯基-二-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑衍生物的合成

以2,5-二巯基-1,3,4-噻二唑为原料, 与水合肼缩合, 生成2,5-二肼基-1,3,4-噻二唑. 2,5-二肼基-1,3,4-噻二唑与苯甲酰氯反应生成2,5-二酰肼基-1,3,4-噻二唑, 以POCl₃为环合剂环合酰肼基-1,3,4-噻二唑, 合成3,6-二取代苯基- 二-1,2,4-三唑并[3,4-b]-1,3,4-噻二唑衍生物, 合成的新化合物的结构通过元素分析、红外光谱、核磁共振氢谱和质谱予以证实, 并提出了环化反应机理.     

Synthesis of 6-aryl-3-cinchophenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

In recent years, fused heterocycles have been found to possess many unique properties in synthesis and pharmacology. Especially, 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles derivatives have been attracting much attention of chemists and pharmacologists because of their broad-spectrum biological activities such as antibacterial¹, hypotensive and CNS depressant² activities. We have prepared some 3,6-substituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and found that these compounds exhibited antimacrobial, insecticidal and promote plant growth.^3-5 Cinchophen had been used widely as medicine in clinic,but has been obsolete in recent years due to its by-effect. In order to seek for other uses of cinchophen, as a continuation of our preceeding studies, we used cinchophen as the starting material to synthesize ten new 6-aryl-3-cinchophenyl-l,2,4-triazolo[3,4-b]-l,3,4-thiadiazoles 5a-j. Compound 1 was prepared by the reaction of cinchophen and ethanol in the presence of sulfuric acid. 1 then reacted with hydrazine hydrate in absolute ethanol to give 2 which yielded 3 on treatment with CS₂ and KOH. On refluxing of 3 with excess hydrazine hydrate, 4 was obtained. 4 reacted with various substituted benzoic acids in the presence of POCl₃ to afifort 5a-j.     

Synthesis and Biological Activities of Novel 1,4-Bridged Bis-1,2,4-Triazoles,Bis-1,3,4-Thiadiazoles and Bis-1,3,4-Oxadiazoles

Abstract

The terephthalic acid hydrazide(1) reacted with phenyl/benzyl isothiocyanate2a,bto yield the corresponding bis-thiosemicarbazides4a,b,viaacid hydrolysis of the intermediate 3whereas cyclization of4gave the bis-1,2,4-triazoles 5,6and bis-1,3,4-thiadiazoles7,8. Similarly, compound 1reacted with phenyl isocyanate9to give the bis-semicarbazide10, which was cyclized to the bis-oxadiazole 11and/or bis-1,2,4-triazole12in POCl_ti3and NaOH respectively.     

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 OF POLYFUSED THIENO(2,3-b)THIOPHENES PART 1: SYNTHESIS OF THIENOPYRIMIDINE DERIVATIVES

Abstract

3,4-Diamino-2,5-dicarbethoxythieno(2.3-b)thiophene 1 reacted with malononitrile or ethyl cyanoacetate to afford bis(thienopyrimidin-4-one) derivatives 2_a.b The reaction of compound 1 with o-aminothiophenol, o-aminophenol or o-phenylenediamine gave benzothiazolyl-, benzoxazolyl-, benzoimidazolylthienothiophene 3_a-c, Chloroacetylation of compound 1 and reacting the resulting compound 4 with malononitrile furnished thienopyrolopyrimidine 6. Fusion of compound 1 with formamide yielded bis(thienopyrimidine) 7 which reacted with POCI₃/PCl₅ to yield the corresponding chloro derivative 8 which was converted into the corresponding hydrazine derivative 9. Treatment of compound 1 with CS₂, NaOH and 1,2 dibromoethane produced the corresponding 1.3 dithiolane 11 which also treated with chloroacetyl chloride or ethyl mercaptoacetate to get the corresponding β-lactame 12 or thiazolidinone 13. On reacting compound 1 with CS₂, NaOH and (CH₃)₂S0₄ produced the corresponding bi(dithiocarbamate methyl ester) 14 which treated with hydrazine hydrate to yield the corresponding bis(thienopyrimidine) derivative 15. This compound reacted with Lawesson's reagent (LR) to give the desired compounds 16 and 17. While its reaction with (CH₃)₂ SO₄ and NaOH furnished the corresponding methyl derivative 18. Fusion of compound 18 with aniline afforded compound 19. Compound 19 was allowed to react with ethyl acetoacetate, acetylacetone, α-oxoketene dithioacetal, ethoxymethylene malononitrile or LR to get the described compounds 2O_a.b-24 respectively.     

Synthesis and Reactions of 3‐Methylthiazolo[3,2‐a]Benzimidazole‐2‐Carboxylic Acid Hydrazide: Synthesis of Some New Pyrazole, 1,3‐Thiazoline, 1,2,4‐Triazole and 1,2,4‐Triazolo[3,4‐b]‐1,3,4‐Thiadiazine Derivatives Pendant to Thiazolo[3,2‐a]Benzimidazole Moiety

The reaction of 3‐methylthiazolo[3,2‐a]benzimidazole‐2‐carboxylic acid ethyl ester (1) with hydrazine hydrate gives the hydrazide 2 which reacts with CS₂/KOH to afford the potassium salt 3. Treatment of 3 with l‐aryl‐2‐bromoethanones 4a,b afforded the 1,3‐thiazoline derivatives 6a,b, respectively, while the reaction of 3 with hydrazine hydrate afforded 1,2,4‐triazole‐3‐thione derivative 9. The reaction of 9 with l‐aryl‐2‐bromoethanones 4a,b and with hydrazonyl chlorides 11a,b gave the 1,2,4‐triazolo[3,4‐b]‐1,3,4‐thiadiazine derivatives 10a,b and 12a,b, respectively. Treatment of hydrazide 2 with phenyl isothiocyanate in refluxing benzene gave the thiosemicarbazide derivative 16. The latter reaction gave 1,3,4‐oxadiazole derivative 17 when benzene was replaced by DMF. Cyclization of the thiosemicarbazide derivative 16 with NaOH resulted in the formation of the 1,2,4‐triazole‐3‐thione derivative 18.     

Facile synthesis and characterization of novel pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-one and pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine incorporating 1,3-diarylpyrazole moiety

4-(3-(4-Hydroxyphenyl)-1-phenyl-1H-pyrazol-4-yl)-6-phenyl-2-thioxo-1,2-di hydro-pyridine-3-carbonitrile (1) reacted with ethyl chloroacetate (2) in ethanolic sodium acetate solution to yield the corresponding ethyl (3-cyanopyridin-2-ylsulphanyl)acetate derivative 3. Intramolecular cyclization of compound 3 was achieved by its heating in DMF containing potassium carbonate to afford the corresponding ethyl 3-aminothieno[2,3-b]pyridine-2-carboxylate derivative 4 which reacted with hydrazine hydrate in refluxing pyridine to yield the starting material 3-aminothieno[2,3-b]pyridine-2-carbohydrazide derivative 7. Compound 7 reacted with different reagents such as triethylorthoformate, formic acid, acetic acid and acetic anhydride to afford the target molecules pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-one derivatives 8–10, 12 and 13 in good to excellent yields. On the other hand, pyridine-2(1H)-thione derivative 1 reacted with hydrazine hydrate in refluxing pyridine to give the other starting material 3-amino-1H-pyrazolo[3,4-b]pyridine derivative 20 which reacted with acetylacetone under reflux to afford the target molecule pyrido[2′,3′:3,4]pyrazolo[1,5-a]-pyrimidine derivative 21 in a good yield. The structures of target molecules were elucidated using elemental analyses and spectral data.     

Pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9(6H8H)-diones

Some 5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9-(6H,8H)-diones (4 a–d) have been synthesised by the condensation of 3-alkyl-4-amino-5-mercapto-(1,2,4)-triazoles (1 a–d) with 5-bromobarbituric acid (2a). Similarly some 9a-nitro-5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9(8H,9aH)-diones (5 a–d) have been obtained by the condensation of1 a–d with 5-bromo-5-nitrobarbituric acid (2b) and final cyclisation withPPA. The structures have been confirmed by PMR spectra and analytical results.

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Pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(6H,8H)-dione

Zusammenfassung Es wurden einige 5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(6H,8H)-dione (4 a–d) mittels Kondensation von 3-Alkyl-4-amino-5-mercapto-(1,2,4)-triazolen (1 a–d) mit 5-Brombarbitursäure (2 a) dargestellt. Des weiteren wurden einige 9a-Nitro-5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(8H,9aH)-dione (5 a–d) über die Kondensation von1 a–d mit 5-Brom-5-nitrobarbitursäure (2 b) und anschließender Cyclisierung mitPPA synthetisiert. Die angeführten Strukturen wurden mittels PMR-Spektren und analytischen Daten abgesichert.

     

Synthesis of 4-amino-5-(4,6-diphenyl-2-pyrimidinyl)-3,4-dihydro-2H-1,2,4-triazole-3-thione and its reactions with C-electrophiles

4-Amino-5-(4,6-diphenyl-2-pyrimidinyl)-3,4-dihydro-2H-1,2,4-trazole-3-thione is formed from the reaction of 4,6-diphenylpyrimidinecarboxylic acid or its ethyl ester with thiocarbonyl hydrazide. Alkylation of the product leads to S-alkyl derivaties or 6-substituted 3-(4,6-diphenyl-2-pyriimidinyl)-7H-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine. Acetylation of 4-amino-5-(4,6-diphenyl-2-pyrimidinyl)-3,4-dihydro-2H-1,2,4-triazole-3-thione gave under different conditions monoacetyl-, diacetyl, and triacetyl derivatives at the amino group and the N₍₂₎ atom, whereas benzoylation gave a benzoyl group at the amino group and 3-(4,6-diphenyl-2-pyrimidinyl)-6-phenyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, 1088–1094, July, 2007.     

Convenient Synthesis of Some 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines Bearing 3-Methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}moiety as Possible Antimicrobial Activity

4-Amino-4H-3-methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}-1,2,4-triazole-5thi-ol (1) was condensed with various substituted aromatic aldehydes or acid chlorides to yield a series of arylideneamines 2 or aroylamines 3. These were easily cyclized to the corresponding 6-aryl-3-methylthio7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl-1,2,4-triazolo [3,4-b]-1,3,4-thiadiazoles (4) on treatment with palladium-on-charcoal or phosphorus oxychloride. Compounds 4 were also prepared directly via the reaction of 1 with aromatic carboxylic acids in the presence of phosphorus oxychloride. Cyclocondensation of 1 with a variety of two-carbon cyclizing reagents, namely chloroacetone, pyruvic acid, benzoylformic acid, and benzoin led to the formation of 3-methylthio{7H-1,2,4-triazolo[1,5-d]tetrazol-6-yl}-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines (5?8). Some of the newly synthesized compounds were tested for their antibacterial and antifungal activity against a variety of microorganisms.