New 1,2,3-selenadiazole and 1,2,3-thiadiazole derivatives

New 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives, 14-23, were prepared from the ketones 1-5 via the corresponding semicarbazones or hydrazones 6-12. The Hurd-Mori and Lalezari methods were used, respectively, for the preparation of these 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives. The intermediate 13 was also trapped, separated and fully characterized. These derivatives are important for photocrosslinking processes and due to their potential biological activity.     

Synthesis of 5-amino-1,2,3-thiadiazole

A convenient method is proposed for the synthesis of ethyl phthalimidoethylideneaminocarbamate, an intermediate in the synthesis of 5-amino-1,2,3-thiadiazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 112–113, January, 1989.     

Die thermische wolff-umlagerung der 1,2,3-thiadiazole

Thermal nitrogen elimination of 1,2,3-thiadiazoles leads to primary fragments, which rearrange to thioketenes. In the presence of high boiling alcohols like diglycol, the corresponding esters can be isolated in good yields. Benzo-1,2,3-thiadiazole, which does not rearrange, is an exception, because of the integrity of the aromatic nucleus.     

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.     

Nucleophilic substitution in 1,2,3-thiadiazoles

By reactions of nucleophilic substitution of the halogen atom in 5-halo-1,2,3-thiadiazoles (IV), we have obtained 5-amino- (I, V), hydrazino-(VI, VII, IX, X), and mercapto- (VIII) 1, 2, 3-thiadiazoles. We show that upon reaction with amines, a mixture of 5-amino-1, 2, 3-thiadiazoles (I) and 5-mercapto-1, 2, 3-triazoles (II) is formed, and also the reaction product of compounds I and IV,: the selectivity of this process depends only on the type of solvent.Organic Synthesis Technology Department, Urals State Technical University—UPI, Ekaterinburg 620002. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 554–559, April, 1994. Original article submitted February 28, 1994.     

Spontaneous ring transformation of a 5-azido-1,2,3-thiadiazole

The reaction of 4-carbethoxy-5-chloro-1,2,3-thiadiazole ($\text{1}$) with sodium azide results in the formation of ethyl α-thiatriazolyldiazoacetate ($\text{3}$) instead of the corresponding azide ($\text{2}$). Two plausible mechanisms for this new rearrangement are formulated.     

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 and characterization of some new 1,2,3-thiadiazole and 1,2,3-selenadiazole triterpene derivatives from allobetulone and 2-oxoallobetulin

Abstract

The synthesis of new 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives from triterpenoid ketones has been investigated via the corresponding semicarbazones. The intermediates 5, 8 have also been isolated, separated and their structures identified. The Hurd–Mori reaction and Lalezari method have been applied to synthesize a series of new substances 6 and 7. The regioselectivity of the functionalization mostly was centered at the C-3 position for the products 9 and 10. The structures of these compounds were confirmed by 2D-NMR spectroscopy.     

The preparation of dicyano-1,3,4-thiadiazole and tricyanothiazole via 1,2,3-dithiazole chemistry

Treatment of 1,2-bis(4-chloro-5H-1,2,3-dithiazol-5-ylidene)hydrazine 4 with benzyltriethylammonium iodide (1 equiv) affords dicyano-1,3,4-thiadiazole 3 and 5-cyano-1,3,4-thiadiazole-2-carboxamide 5 in 79 and 21% yields, respectively. By using polymer bound triphenylphosphine instead of benzyltriethylammonium iodide the dicyano-1,3,4-thiadiazole 3 can be isolated in 70% yield without chromatography. The reaction of DAMN with Appel salt 8 gave 2-(4-chloro-5H-1,2,3-dithiazol-5-ylideneamino)-2-(4-chloro-5H-1,2,3-dithiazol-5-ylidene)acetonitrile 7 (14%), 2,3-bis-(4-chloro-5H-1,2,3-dithiazol-5-ylideneamino)fumaronitrile 10 (14%), and 2,3-bis(4-chloro-5H-1,2,3-dithiazol-5-ylideneamino)maleonitrile 11 (24%) together with other products. The maleonitrile 11 isomerizes into the fumaronitrile 10 on irradiation at 365 nm. Reaction of aminoacetonitrile with Appel salt 8 gives the (dithiazolylidene)acetonitrile 7 in 33% yield. Treatment of (dithiazolylidene)acetonitrile 7 with polymer bound triphenylphosphine gives tricyanothiazole 6 in 76% yield. A rational general mechanism for the transformation of bisdithiazoles to percyanoheteroles is proposed.     

Synthesis and biological evaluation of novel 1,2,4-triazole containing 1,2,3-thiadiazole derivatives

A series of novel 1,2,4-triazoles containing 1,2,3-thiadiazole derivatives were designed and synthesized. Their structures were confirmed by melting points, IR, 1H NMR, and elemental analysis and ESI-MS or HRMS. Preliminary bioassays indicated that these compounds exhibited very good insecticidal activity against Aphis laburni at 100 μg/mL, with mortality no less than 95%. Compounds 6a, 6c, 6f, 61 showed higher curative activity against TMV and compound 6h showed a higher induction effects against TMV in vivo at 100 μg/mL. Collectively, our data demonstrate a new strategy for control of insects and viruses.     

Selenium heterocycles XXV. Synthesis of thieno[3,4-d][1,2,3]-thiadiazole,selenolo[3,4-d][1,2,3]thiadiazole and pyrrolo[3,4-d][1,2,3]-thiadiazole. Three novel ring systems

Starting from the readily available 4-bromomethyl-5-benzoyl-1,2,3-thiadiazole and 5-bromomethyl-4-benzoyl-1,2,3-thiadiazole; thieno[3,4-d][1,2,3]thiadiazole, selenolo[3,4-d][1,2,3]-thiadiazole and pyrrolo[3,4-d][1,2,3]thiadiazole were synthesized in good yield.     

3-Aryl-4,5-dichloro-1,2,3-thiadiazolium salts — Synthons for the preparation of mesoionic compounds of the 1,2,3-thiadiazole series

The high mobility of the chlorine atom at the 5-position of 3-aryl-4,5-dichloro-1,2,3-thiadiazolium salts facilitates a ready preparation of mesoionic 3-aryl-1,2,3-thiadiazoles with an exocyclic oxygen, sulfur or arylimino group at the 5-position. In an aqueous alcoholic solution of sodium nitrite, the halogens in the 4- and 5-positions are substituted with the formation of 3-aryl-5-nitro-1,2,3-thiadiazolium-4-olates.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1552–1554, November, 1989.     

Synthesis,Crystal Structure and Biological Activity of N-tert-butyl-N-(4-methyl-1,2,3-thiadiazole)-5-yl-N’-(4-methyl-1,2,3-thiadiazole)-5-formyl-N’-3,5-dichloropyridin-2-yl-diacylhydrazine

The title compound N-tert-butyl-N-(4-methyl-1,2,3-thiadiazole)-5-yl-N'-(4-me-thyl-1,2,3-thiadiazole)-5-formyl-N'-3,5-dichloropyrid-2-yl-diacylhydrazines (C18H17Cl2N7O3S2, Mr = 514.41) has been synthesized by the reaction of N-tert-butyl-N'-3,6-dichloropyridine-2-formyl hydrazine with 4-methyl-1,2,3-thiadiazole-5-carbonyl chloride and triethylamine, and its structure was characterized by 1H NMR, HR MS, and single-crystal X-ray diffraction. The crystal of the title compound belongs to monoclinic, space group C2/c with a = 27.726(8), b = 11.045(3), c = 14.507(4), β = 96.758(4)°, Z = 8, V = 4412(2) 3, Dc = 1.549 g/cm3, μ = 0.521 mm-1, F(000) = 2112, R = 0.0405 and wR = 0.1153. X-ray analysis indicates that all rings are non-planar in this molecule. The bioassay results indicate that both the title compound and the positive control RH-5992 have weak fungicide activities, while the title compound has good insecticidal activity against Plutella xylostella L. and no insecticidal activity against Culex pipiens pallens.     

Early events in the photochemistry of 1,2,3-thiadiazole studied by ultrafast time-resolved UV-vis and IR spectroscopies

Photochemistry of 4-methyl-5-carboethoxy-1,2,3-thiadiazole (MCT) in solution was studied at room temperature using UV-vis and IR transient absorption spectroscopies (λ(ex) = 266 nm). Three deactivation pathways are discussed: thiirene formation, thioketene generation, and the internal conversion by repopulating MCT in the ground state. Ultrafast techniques show a very fast rise (<0.4 ps) of thiirene species in acetonitrile, possibly as a result of a rearrangement in the singlet excited state of MCT in concert with molecular nitrogen extrusion. The remarkable stability of thiirene in solution on a millisecond time scale is limited by the process of dimerization (thiirene-thiirene, thiirene-thioketene). NMR analysis permitted identification of stable photoproducts as 1,3-dithietane, 1,3-dithiole, and thiophene derivatives.     

Methylation of 4-phenyl-1,2,3-thiadiazole. Reaction of nucleophiles with N-methyl-1,2,3-thiadiazolium salts and the crystal structure of the products

The methylation of 4-phenyl-1,2,3-thiadiazole yields both N-methylated products. These react differently with nucleophiles. The structure of the product of the reaction with morpholine has been determined through X-ray diffraction analysis.