Vinyl derivatives of heterocyclic systems and their polymers: 3-vinyl-1,2,5-thiadiazole

3-Vinyl-1,2,5-thiadiazole is prepared by different methods: by one-pot reaction from 1,2,5-thiadiazole, by cyclization of 3,4-diamino-1-butene, and by the Wittig procedure either from 1,2,5-thiadiazolylimethylenetriphenyl-phosphorane or from 3-formyl-1,2,5-thiadiazole. Some physical and chemical properties are described.     

Reduction of 3,4-bis(4-amino-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole 2-oxide

Russian Journal of Organic Chemistry -     

4-Alkyl(aryl)-3-amino-1,2,5-thiadiazole 1,1-dioxides

Two methods have been developed for the synthesis of 3-amino-1,2,5-thiadiazole 1,1-dioxides; one leads to 4-alkyl derivatives, the other to 4-aryl analogs.     

Synthesis of nonsymmetrically 3,4-disubstituted 1,2,5-thiadiazole dioxides

A synthetic pathway for obtaining arylamino, alkylamino 3,4-disubstituted 1,2,5-thiadiazole dioxide derivatives has been developed. This methodology could be applied to obtain potential biologically active molecules.     

Reductive transformation of 3-methoxy-2-methyl-3,4-diphenyl-2,3-dihydro-1,2,5-thiadiazole 1,1-dioxide in the reaction with thiourea and HC1

Russian Chemical Bulletin -     

The synthesis of symmetrical bis-1,2,5-thiadiazole ligands

We have been engaged in a search for coordination catalysts for the copolymerization of polar monomers (such as vinyl chloride and vinyl acetate) with ethylene. We have been investigating complexes of late transition metals with heterocyclic ligands. In this report we describe the synthesis of a symmetrical bis-thiadiazole. We have characterized one of the intermediates using single crystal X-ray diffraction. Several unsuccessful approaches toward 1 are also described, which shed light on some of the unique chemistry of thiadiazoles.     

Preparation of 1,2,5-thiadiazole-3-carboxaldehydes

1,2,5-Thiadiazole-3-carboxaldehydes 1a-c were prepared by the acid-catalyzed decomposition of 3-azido-methyl-1,2,5-thiadiazoles 2a-c in 68-83% yields, respectively. Pyrolysis of 2a and 2b afforded the imidazoles 4a and 4b in low yields. NBS -bromination of 1a and 1b gave the corresponding carboxylic acids 10a and 10b via acid bromides 9. Azides 2a and 2b gave the s-triazines 8a and 8b on treatment with NBS.     

Preparation of 3-hydroxy- and 3-methoxy-N-heteroaryl-2-methyl-4-pyridones

A number of new 3-hydroxy- and 3-methoxy-2-methyl-4-pyridones substituted on the nitrogen atom with selected heterocycles has been prepared. Novel chelating properties of the hydroxy-compounds are expected.     

Synthesis of 3-(6-R-Benzothiazol-2-yl)-4-methyl-1,2,5-oxadiazoles

The nitrosation of N-aryl-3-oxobutanethioamides afforded 1-(6-R-benzothiasol-2-yl)-1-hydroxyimino-2-propanones that at oximation with hydroxylamine were converted into 1-(6-R-benzothiazol-2-yl)-1,2-dihydroxyiminopropanes. The latter were dehydrated by heating with succinic anhydride at 140°C yielding therewith 3-(6-R-benzothiazol-2-yl)-4-methyl-1,2,5-oxadiazoles.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 759–761.Original Russian Text Copyright © 2005 by Britsun, Borisevich, Samoilenko, Lozinskii.     

Neue acetonylsubstituierte Azole II. 3-Acetonyl-1,2,4-oxadiazole, 2-Acetonyl-1,3,4-oxadiazole und 5-Acetonyl-1,2,4-thiadiazole

3-Acetonyl-1,2,4-oxadiazoles and 2-acetonyl-1,3,4-oxadiazoles are accessible starting with the ketal of acetoacetamide oxime and the ketal of acetoacetic acid hydrazide, respectively. 5-Acetonyl-1,2,4-thiadiazoles are obtained from 5-chloro-1,2,4-thiadiazoles andtert.-butyl acetoacetate. These Acetonyl-azoles are starting materials for three series of azolylvinyl phosphates and phosphonates.

Herrn Prof. Dr.Klaus Weissermel zu seinem 60. Geburtstag.     

Synthesis of 3-methyl-4-(5-R-1H-1,2,4-triazol-3-yl)-1,2,5-oxadiazoles

A number of 3-methyl-4-(5-R-1H-1,2,4-triazol-3-yl)-1,2,5-oxadiazoles were obtained in high yields by thermal dehydration of acylated 4-methyl-1,2,5-oxadiazole-3-carboxamide hydrazones.     

The chemistry of 1,2,5-thiadiazoles V. Synthesis of 3,4-diamino-1,2,5-thiadiazole and [1,2,5] thiadiazolo[3,4-b]pyrazines

The o-diamine, 3,4-diamino-1,2,5-thiadiazole ( 2 ), was synthesized from 3,4-dichloro-1,2,5-thiadiazole ( 3 ) hy three methods. Aqueous glyoxal cyclized 2 into [1,2,5]thiadiazolo[3,4–6]-pyrazine ( 14 ). 3,4-Dichloro-1,2,5-thiadiazole 1,1-dioxide ( 18 ) reaeted with 2 to give 1,3-dihydro-bis[1,2,5]thiadiazolo[3,4-b:3′,4′-e]pyrazine 2,2-dioxide ( 19 ). The reaction of 2 with selenium oxyehloride led to [1,2,5]selenadiazolo[3,4-c] [1,2,5]thiadiazole ( 12 ). Ring closure of 2,3-diaminoquinoxaline ( 4 ) with thionyl chloride or selenium oxychloride gave [1,2,5]thiadiazolo-[3,4-b]quinoxaline ( 21 ) and [1,2,5]selenadiazolo[3,4-b]quinoxaline ( 22 ), respectively. Sulfurous acid reduced 21 to the 4,9-dihydro derivative 23 , which was reoxidized to 21 with chloranil. Aqueous hase hydrolyzed 21 to 4 via the hydrated intermediate 24 . Aqueous glyoxal cyclized 4 to the covalent hydrate of pyrazino[2,3-b]quinoxaline ( 26 ), 27 , which was dehydrated to 26 . Compound 26 underwent rapid addition of two alcohols in a process analogous to covalent hydration.     

2-取代硫醚-5-脱氢松香基-1,3,4-恶二唑/噻二唑类化合物的合成及生物活性

以脱氢松香酸为原料,经酯化、肼解、关环和亲核取代反应得到了2-取代硫醚-5-脱氢松香基-1,3,4-恶二唑和2-取代硫醚-5-脱氢松香基-1,3,4-噻二唑类化合物。通过IR、MS、1H NMR和元素分析对产物进行了表征。初步生物活性检测结果表明,所有目标化合物都表现出一定的除草活性。     

2-Amino-5-methyl-1,3,4-thiadiazole and 2-amino-5-ethyl-1,3,4-thiadiazole

The structures of 2-amino-5-methyl-1,3,4-thia­diazo­le, C₃H₅N₃S, and 2-amino-5-ethyl-1,3,4-thia­diazo­le, C₄H₇N₃S, have been determined for comparison with unsubstituted 2-amino-1,3,4-thia­diazo­le. Despite their different space groups (P2₁/n and Pbca, respectively), the packing modes of the methyl and ethyl derivatives are similar, with comparable three-dimensional hydrogen-bonding associations. This is in contrast to the hydrogen-bonding network in 2-amino-1,3,4-thia­diazo­le, which is one-dimensional and has denser packing. It is shown that both packing forms are different polymorphs of a specific subunit of each array.     

Mononuclear isoheterocyclic rearrangements. Note I. Interconversion of 3-benzoylamino-5-methyl-1,2,4-oxadiazole and 3-acetylamino-5-phenyl-1,2,4-oxadiazole

The first example of mononuclear isoheterocyclic rearrangement is reported. The 3-benzoylamino-5-methyl-1,2,4-oxadiazole ( 5 ) furnishes through a reversible process (slowly at room temperature in methanol, acetone or dioxane, fast in DMSO or in methanol in the presence of strong bases) a mixture of 5 and 3-acethylamino-5-phenyl-1,2,4-oxadiazole ( 6 ). The equilibrium process can be achieved also by heating 5 at 181° and the same reaction mixture can be obtained using 6 as the starting material. 3-Trichloroacetylamino-5-methyl-1,2,4-oxadiazole ( 7 ) was unaffected by similar treatment. The results obtained are discussed.