Synthesis and properties of 5-amino-1,2,3-thiadiazole-4-carbothioamides

5-Amino-1,2,3-thiadiazole-4NR-carboxamides were reacted with P₄S₁₀, and 5-NR-amino-1,2,3-thiadiazole-4-carbonitriles with-H₂S. The reversible rearrangement of 5-amino-1,2,3-thiadiazole-4-NR-carbothioamides to 5-NR-amino-1,2,3-thiadiazole-4-carbothioamides was discovered.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1269–1273, September, 1988.     

The methylation of 1,2,3-thiadiazole-4-carbothioamides

A study was carried out on the methylation of 5-(3-phenylureido)- and 5-amino-1,-2,3-thiadiazole-4-carbothioamides. A new rearrangement was observed for 5-amino-1,2,3-thiadiazole-4-S-methylcarbothioimidates to give 5-methylthio-1,2,3-triazole-4-carbothioamides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 938–940, April, 1990.     

Synthesis of 4-thioacetyl-1,2,3-thiadiazoles. Reversible rearrangement of N-Substituted 5-methyl-1,2,3-thiadiazole-4-carbothioamides

The equilibrium in the reversible rearrangement of 5-methyl-1,2,3-thiadiazole-4-carbothioamides into 5-amino-4-thioacetyl-1,2,3-thiadiazoles is displaced toward the former, and polar solvents favor increased fraction of the thioketone.     

Study of direction of cyclization of malonodithioamides as a method of investigation of reactivity of α-diazothioacetamides

The reaction of malonothioamides with benzene-sulfonyl azide and 2-azido-3-ethylbenzthiazolium tetrafluoroborate gave amides of 2-diazothiomalonic acid, which underwent cyclization to a mixture of 5-N-R-amino-1,2,3-thiadiazole-4-carbothioamides and 5-amino-1,2,3-thiadiazole-4-N-R-carbothioamides. The ratio of the isomeric thiadiazoles formed in this reaction is the same as in the reactions of 2-diazo-2-cyanoacetamides, 5-amino-1,2,3-thiadiazole- and 5-mercapto-1,2,3-triazole-4-carboxamides with P₄S₁₀ and of 5-amino-1, 2,3-thiadiazole-4-carbonitriles with H₂S; it is characteristic of the influence of substituents on the reactivity of -diazothioacetamides. It was found that the cyclization of the diazo compounds is accelerated when electron-acceptor substituents are attached to the nitrogen atom of the carbothioamide group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1106–1112, August, 1992.     

Study of the characteristics of rearrangements of 5-amino-1,2,3-thiadiazole-4-carbothioamides

Using NMR spectroscopy, we have determined the relative stability and the effect of the solvent on the ratio of isomeric NN-disubstituted 5-amino-1,2,3-thiadiazole-4-carbothioamides in a mixture. We carried out chromatographic separation of a mixture of 5-benzylamino-1, 2, 3-thiadiazole-4-N-methylcarbothioamide and 5-methylamino-1, 2, 3-thiadiazole-4-N-benzylcarbothioamide and we show that when each compound dissolves, it rapidly isomerizes with formation of the initial composition. We conclude that the orientation of the rearrangement process is thermodynamically controlled.     

Rearrangement of 5-amino-1,2,3-thiadiazole-4-carbothioamides

Conclusions A new rearrangement in the series of 5-amino-1,2,3-thiadiazole-4-carbothioamides was observed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1126–1128, May, 1988.     

2-Azido-1,3,4-thiadiazoles, 2-Azido-1,3-thiazoles,and Aryl Azides in the Synthesis of 1,2,3-Triazole-4-carboxylic Acids and Their Derivatives

Diazotization of 2-amino-1,3,4-thiadiazoles gave 1,3,4-thiadiazole-2-diazonium sulfates which were converted to 2-azido-1,3,4-thiadiazoles. The latter reacted with ethyl acetoacetate in the presence of sodium methoxide in methanol to produce 1-(5-R¹-1,3,4-thiadiazol-2-yl)-5-R²-1H-1,2,3-triazole-4-carboxylic acid derivatives. The reactions of 2-azido-5-methyl-1,3,4-thiadiazole and 2-azido-1,3-thiazole with ethyl 3-(1,3-benzodioxol-5-yl)-3-oxopropanoate led to the formation of 1,2,3-triazole ring under milder conditions (K₂CO₃, DMSO). Various 1,2,3-triazole-4-carboxylic acid derivatives were synthesized.     

Oxide der 1,2,3-thiadiazole—III : Darstellung und eigenschaften der cycloalkeno-1,2,3-thiadiazole und ihrer mono- und trioxide

Cycloalkeno-1,2,3-thiadiazoles (3a–d) can be prepared from cycloalkanone-tosylhydrazones (2a–d) by treatment with SOCl₂. Oxidation of 3a–d with peracetic acid yields 1,2,3-thiadiazole-2-oxides (4a–d) and 1,2,3-thiadiazole-1,1,2-trioxides (5a–c). A characterisation of these three classes of compounds is performed by discussion of their UV, IR, NMR and mass spectra.     

Reactions of 5-dialkylamino-1,2,3-thiadiazole-4-carbaldehydes with amines as a method for the synthesis of 1,2,3-triazole-4-carbothioamides

A method for the synthesis of previously inaccessible 5-dialkylamino-substituted 1,2,3-thiadiazole-4-carbaldehydes was developed. Ring transformation in these compounds induced by primary aliphatic and aromatic amines, hydroxylamines, and N-substituted hydrazines resulted in the synthesis of a broad range of 1,2,3-triazole-4-carbothioamide.     

A tandem of the Cornforth rearrangements of 4-(1,2,3-triazol-1-yl)iminomethyl-1,2,3-thiadiazole

The method for the synthesis of 5-(2,6-dimethylmorpholino)-1,2,3-thiadiazole-4-carbaldehyde was proposed. Its reaction with sodium 1-amino-4-(N-methyl)carbamoyl-1,2,3-triazol-5-olate proceeds through a tandem of the Cornforth rearrangements. The initially formed azomethine isomerizes into sodium 4"-(2,6-dimethylmorpholino)thiocarbonyl-4-(N-methyl)carbamoyl-1,1"-bis[1,2,3]triazolyl-5-olate, which then rearranges to give sodium 4-{N-[4-(2,6-dimethylmorpholinothiocarbonyl)-1,2,3-triazol-1-yl]carbamoyl}-1-methyl-1,2,3-triazol-5-olate.     

Synthesis of 1,2,3-thiadiazole-5-carbaldehydes and their conversion into 6aδ4-Thia-1,2,5,6-tetraazapentalenes

A convenient method for the synthesis of the virtually unknown 1,2,3-thiadiazole-5-carbaldehydes consists in monobromination of the 5-methyl derivatives, followed by treatment with sodium azide and decomposition in concentrated sulfuric acid ( 6 → 7 → 9 → 10 ). These compounds can be transformed via methylation of the corresponding hydrazones 12 into 6aδ⁴-thia-1,2,5,6-tetraazapentalenes 13 .     

1,2,3-thiadiazoles. I. Synthesis of sodium (or potassium) 1,2,3-thiadiazole-4-thiolates via thiocarbazonate esters and N-acylthiohydrazonate esters

A general synthesis of 1,2,3-thiadiazole-4-thiolates 1 and their derivatives 2–3 by an extension of the Hurd-Mori 1,2,3-thiadiazole synthesis is described. Treatment of methyl (or ethyl) [1-(alkylthio)alkylidene]hydrazinocarboxylates 11 (thiocarbazonate esters) or other N-acylthiohydrazonate esters [Y = ureido ( 12 ) or arenesulfonyl ( 13 )] with thionyl chloride affords 2–3 efficiently. Intermediates 11–13 are readily obtained from the N²-thioacylcarbazates 8 , N³-thioacylsemicarbazides 9 , or N²-thioacyl-N¹-(p-toluenesulfonyl)hydrazides 10 , respectively, by S-alkylation. Physicochemical properties of the 1,2,3-thiadiazoles 1–3 and N-acylthiohydrazonate esters 11–13 are also described.     

Heterocycloaddition of thermally generated 1,2-diaza-1,3-butadienes to [60]fullerene

Stable C₆₀-fused tetrahydropyridazine derivatives were synthesized through the hetero-Diels-Alder cycloaddition of C₆₀ with 1,2-diaza-1,3-butadienes, which were generated in situ by the thermal extrusion of sulfur dioxide from 2,5-dihydro-1,2,3-thiadiazole-1,1-dioxides.     

Mass spectral fragmentation pattern of 4-carboxy-and 4-methoxycarbonyl-5-methyl(or phenyl)-2-aryl-2H-1,2,3-triazoles

4-Carboxy-5-methyl-2-aryl-2H-1,2,3-triazoles undergo considerable fragmentation on electron impact including loss of OH and H₂O from the molecular ions and rupture of the triazole ring. 4-Carboxy-5-phenyl-2-aryl-2H-1,2,3-triazoles, on the other hand, show no loss of H₂O from the molecular ions.     

3-(4-Thiocarbamoyl-1,2,3-triazol-1-yl)benzo-15-crown-5: synthesis and properties

A reaction of 1,2,3-thiadiazole-4-carbaldehyde with 3-aminobenzo-15-crown-5 involves the Cornforth rearrangement of the 1,2,3-thiadiazole ring, which leads to 1,2,3-triazole-4-carbothioamide containing the benzocrown ether substituent in position 1 of the triazole ring. Reversible formation of the isomeric thiadiazole occurs in aprotic nonpolar solvents such as deuterated chloroform. These compounds are suitable for extraction of α-amino acids from an aqueous phase.     

A simple and convenient synthesis of 3-[5-(trifluoromethyl)-1,2,3-triazol-4-yl]cinnamic acids from 4-aryl-6-(trifluoromethyl)-2H-pyran-2-ones and sodium azide

4-Aryl-6-(trifluoromethyl)-2H-pyran-2-ones and ethyl 4-aryl-6-(trifluoromethyl)-2-oxo-2H-pyran-3-carboxylates react with sodium azide to produce highly functionalized CF₃-1,2,3-triazoles: 3-[5-(trifluoromethyl)-1,2,3-triazol-4-yl]cinnamic acids and monoethyl esters of [5-(trifluoromethyl)-1,2,3-triazol-4-yl]arylmethylidene malonic acids.     

Synthesis and Biological Activity of α-Substituted 1,2,3-Thiadiazole-4-Acetic Acid Derivatives

Compounds containing 1,2,3-thiodiazole ring were reported to posses fungicidal¹, herbicidal² and growth regulation properties³. For example, N-phenyl-N'-1,2,3-thiadizazol-5-yl-urea (Thidiazuron, Dropp) has been used as a cotton defoliant⁴, herbicide and was also found to exhibit cytokinin-like activity in bioassay systems. The compound was more effective than Zeatin⁵ and 6-BA⁶. Because the synthesis of 1,2,3-thiodiazole ring is difficult,compounds containing 1,2,3-thiadiazole ring are relatively seldom reported. Herein, we report the synthesis of a novel series of α-substituted-1,2,3-thiadiazole-4-acetic acid derivatives.     

Synthesis,Crystal Structure,and Biological Activity of Naphthalen-2-yl4-methyl-1,2,3-thiadiazole-5-carboxylate

The title compound naphthalen-2-yl-4-methyl-1,2,3-thiadiazole-5-carboxylate (C 14 H 10 N 2 O 2 S,M r=270.31) was synthesized by the reaction of 4-methyl-1,2,3-thiadiazole-5-carbonyl chloride with 2-naphthol,and its structure was characterized by IR,1 H NMR,high-resolution mass spectrometry and single-crystal X-ray diffraction.The crystal belongs to orthorhombic,space group Pbcn with a=23.475(5),b=9.6640(19),c=10.814(2),β=90.00°,Z=8,V=2453.2(9) 3,M r=270.30,D c=1.464 g/cm 3,μ=0.262 mm-1,F(000)=1120,R=0.0444 and wR=0.1099.X-ray analysis revealed that the thiadiazole and naphthalene rings were non-planar,while the thiadiazole ring and the ester group were essentially planar,and two intermolecular hydrogen bonds C(6) H(6)···O(1) and C(14) H(14)···O(1) were observed.The preliminary biological test showed that the title compound had antifungal and antivirus activities against tobacco mosaic virus.     

Synthesis of a phenylazo-derivative of a 1,2,3-thiadiazolium methylide. C-13/N-15 NMR characterization and crystal structure analysis

The N-phenylhydrazone derived from 4-methoxycarbonyl-1,2,3-thiadiazole-5-carbaldehyde 6 is methylated at the N-3 position, yielding the mesoionic compound 8 . The C-13 and N-15 nmr data, as well as the results from a crystal structure analysis, indicate that the molecule is best represented by the resonance forms 8A and 8B . Comparison is made with the previously synthesized thiadiazole derivative 2 which possesses thiapentalene characteristics.     

Heterocyclic studies. 2. 5-Chloro-1H-1,2,3-triazole-4-carboxaldehydes,preparation and rearrangement reactions

A general procedure for synthesis of 5-chloro-1H-1,2,3-triazole-4-carboxaldehydes 4 and the rearrangement reaction of 4-(N-substituted)iminomethylene-1H-1,2,3-triazol-5-ols 6 into N-substituted-1H-1,2,3-triazole-4-carboxamides 7 are described.