Fused 1,2,5-chalcogenadiazoles are often used as biologically active compounds and organic optovoltaic materials. [1,2,5]Thiadiazolo[3,4-b]pyrazines are much less studied due to difficulties in their preparation. In this communication, [1,2,5]thiadiazolo[3,4-b]pyrazine-5,6(4H,7H)-dione, a key precursor for the synthesis of 5,6-dihalo-[1,2,5]thiadiazolo[3,4-b]pyrazines, was prepared via condensation of 1,2,5-thiadiazole-3,4-diamine with oxalic acid or oxalyl chloride. The structure of the newly synthesized compound was established by elemental analysis, high-resolution mass spectrometry, 1H and 13C NMR, IR spectroscopy, and mass spectrometry.

The bromination of benzo[1,2-c:3,4-c']bis([1,2,5]thiadiazole) was studied. An efficient method has been developed for the synthesis of 4,5-dibromobenzo[1,2-c:3,4-c']bis([1,2,5]thiadiazole), an important intermediate for the preparation of highly efficient photochromic diarylethenes for photosensitive and mechanoreactive materials that can be useful in a number of applications, including stress perception and information storage.

Investigations of bromination of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione revealed that the reaction proceeded most efficiently with N-bromosuccinimide in sulfuric acid and depending on the reaction conditions, can give mono-, di-, tri- and tetrabromo derivatives of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione. A series of the major isomers was isolated, and their structure was proven using heteronuclear multiple bond correlation NMR spectroscopy and high-resolution mass spectrometry.

1,2,5-Oxadiazole oxides (furoxans) are well known nitric oxide donors; among them, 4-fluorofuroxans have recently been found to be important photoinduced nitric oxide donors. In this research, it was shown that the reaction of 4,4′-dinitro-[3,3′-bi(1,2,5-oxadiazole)] 2,2′-dioxide with fluoro-containing reagents (tetrabutylammonium fluoride or cesium fluoride) selectively gave the bis-substitution product 4,4′-difluoro-[3,3′-bi(1,2,5-oxadiazole)] 2,2′-dioxide. The structure of the synthesized compound was established by elemental analysis, 13C, 19F-NMR and IR spectroscopy, and mass-spectrometry.

1,2,5-Oxadiazol-3-amines with a heterocyclic substituent in the 4-position are being intensively investigated as compounds with valuable pharmacological activity. In this communication, the reaction of 1,2,5-oxadiazole-3,4-diamine with 2,5-hexanedione was shown to selectively give 4-(2,5-dimethyl-1H-pyrrol-1-yl)-1,2,5-oxadiazol-3-amine as a product of the Paal–Knorr reaction. The structure of the synthesized compound was established by elemental analysis, high-resolution mass spectrometry, 1H and 13C NMR, and IR spectroscopy.

Dibromoderivatives of benzofused chalcogen-nitrogen heterocycles are important precursors in the synthesis of various photovoltaic materials. 4,7-Dibromobenzo[d][1,2,3]thiadiazole is a practically unexplored compound in this series. In this communication, it was shown that the nucleophilic substitution of 4,7-dibromobenzo[d][1,2,3]thiadiazole with morpholine gave selectively 4-substituted product—4-(7-bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, mass-spectrometry, and X-ray analysis.

This paper presents an improved synthesis of 4,7-dibromobenzo[d][1,2,3]thiadiazole from commercially available reagents. According to quantum-mechanical calculations, benzo[d][1,2,3]thiadiazole (isoBTD) has higher values of ELUMO and energy band gap (Eg), which indicates high electron conductivity, occurring due to the high stability of the molecule in the excited state. We studied the cross-coupling reactions of this dibromide and found that the highest yields of π-spacer–acceptor–π-spacer type compounds were obtained by means of the Stille reaction. Therefore, 6 new structures of this type have been synthesized. A detailed study of the optical and electrochemical properties of the obtained π-spacer–acceptor–π-spacer type compounds in comparison with isomeric structures based on benzo[c][1,2,5]thiadiazole (BTD) showed a red shift of absorption maxima with lower absorptive and luminescent capacity. However, the addition of the 2,2′-bithiophene fragment as a π-spacer resulted in an unexpected increase of the extinction coefficient in the UV/vis spectra along with a blue shift of both absorption maxima for the isoBTD-based compound as compared to the BTD-based compound. Thus, a thorough selection of components in the designing of appropriate compounds with benzo[d][1,2,3]thiadiazole as an internal acceptor can lead to promising photovoltaic materials.

The oxidation of hexane-2,3,4,5-tetraone tetraoxime with dinitrogen tetroxide was studied in different solvents. The primary furoxan ring closure was found to occur involving either two central or two terminal oxime groups to form 4,7-dimethyl[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide and the previously unknown 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide. The structure of the latter compound was established by X-ray diffraction.

An efficient and simple synthetic protocol has been developed for preparation of [1,2,5] chacogenadiazolo[3', 4': 5,6] pyrazino[2,3-f][1,10] phenanthrolines. The first Re(I) bromotricarbonyl complex bearing [1,2,5] oxadiazolo[3', 4': 5,6] pyrazino[2,3-f][1,10] phenanthroline as a ligand was synthesized. Crystal structure of complex and free ligand, photo-and electroluminescent properties of fac-bromotricarbonyl ([1,2,5] oxadiazolo[3', 4': 5,6] pyrazino[2,3-f][1,10] phenanthroline) rhenium (I) were investigated.

A new general procedure for the selective synthesis of 1,2,5-thiadiazole 2-oxides (including fused derivatives) 8a,b,c,g,h from the reaction of vic-glyoximes with S2Cl2 and pyridine in acetonitrile was elaborated together with general procedure for the synthesis of 1,2,5-thiadiazoles 7a–i, 10, 12, and 14 from the same starting materials and reagents. Molecular structures of 3,4-dimethyl-1,2,5-thiadiazole 2-oxide 8a and [1,2,5]thiadiazolo[3,4-b]quinoxaline 10 were confirmed by single-crystal X-ray diffraction. Electrochemical properties of 1,2,5-thiadiazole 2-oxides 8 were studied by cyclic voltammetry and different behavior was observed for monocyclic and benzo-fused derivatives. With compounds 8g and 17, previously unknown deoxygenation of 2,1,3-benzothiadiazole 1-oxides was discovered by electrochemical reduction, and resulted 2,1,3-benzothiadiazoles 7g and 19 were detected in the forms of their radical anions by EPR spectroscopy combined with DFT calculations.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A convenient synthetic approach to fused 1,2,5-thiadiazoles and their N-oxides from vicinal nitroamines and sulfur monochloride has been developed.

The reaction temperature has a strong impact on the results of chlorination of 5,6-bis(tertbutylthio)[1,2,5]oxadiazolo[3,4-b]pyrazine that is readily prepared from 5,6dichloro[1,2,5]oxadiazolo[3,4-b]pyrazine and sodium tert-butylsulfide. Monoand bis(sulfenylchlorides) were selectively obtained in high yield and their structure was confirmed by the reaction with morpholine. Treatment of [1,2,5]oxadiazolo[3,4-b]pyrazine-5,6-disulfenyl dichloride with primary aliphatic amines and benzylamine afforded N-substituted [1,3,2]dithiazolo[4,5-b][1,2,5]oxadiazolo[3,4-e]pyrazines in moderate yields. Novel pentacyclic [1,2,5]oxadiazolo[3'',4'':5',6']pyrazino[2',3':5,6][1,2,4]thiadiazino[3,4-b][1,3]benzothiazole, whose structure was confirmed by X-ray diffraction, was obtained by the reaction of this disulfenyl dichloride with 2-aminobenzothiazole.

5H-1,2,3-Dithiazole-5-thiones undergo an unexpected transformation into 5,5-diethoxy-5H-1,2,3-dithiazoles upon treatment with sodium ethoxide; the structure of the products was confirmed by Raman and IR spectra.

The treatment of 5H-1,2,3-dithiazole-5-thiones 1 in chloroform under reflux and 5H-1,2,3-dithiazol-5-ones 2 in THF at room temperature with primary aliphatic amines and benzylamine afforded 1,2,5-thiadiazole-3(2H)-thiones 3 and 1,2,5-thiadiazol-3(2H)-ones 6, respectively. The structure of dithiazolone 3f was confirmed by X-ray diffraction analysis. The reaction of dithiazolone 2e bearing an electron-donating methyl group in the 4-position gave 2-oxoacetamide 7e in high yield. The reaction of thiones 1 with secondary aliphatic amines in DMSO yielded 2-iminothioacetamides 8 in moderate yields together with elemental sulfur. Interestingly, the treatment of dithiazolones 2 with secondary amines under the same conditions afforded 2-oxoacetamides 9—the products of the hydrolysis of corresponding imino derivatives 10, which was isolated as 10b. A general mechanism was proposed for the formation of the products.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

We here report the synthesis and biological evaluation of rare 4-substituted-5-phenylimino, 5-thieno- and 5-oxo-1,2,3-dithiazoles. Dithiazoles were selectively obtained in moderate to high yields (25-73%) via a one-pot reaction from various ethanoneoximes with sulfur monochloride, pyridine in acetonitrile followed by treatment by corresponding nucleophiles (aniline, thioacetamide and formic acid). All the synthesized compounds were screened for their antibacterial (against bacteria Escherichia coli, Salmonella enterica serovar Typhimurium, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus and Listeria inocua), antifungal (against pathogenic strains Candida albicans, Candida glabrata, Candida tropicalis and Issatchenkia orientalis) and antitumor (on human cell lines MCF-7 and MDA-MB-231) activity. 4-(2-Pyridinyl)-5H-1,2,3-dithiazole-5-thione and 4-ethylcarboxyl-5H-1,2,3-dithiazole-5-thione (5d, 5h) that are active against Gram-positive bacteria are significantly active against fungi. 4-(2-Benzofuranyl)-5-phenylimino-5H-1,2,3-dithiazole (4e) exerts antiproliferative activity. (C) 2008 Elsevier Ltd. All rights reserved.

Treatment of N-substituted 2-methyl-1H-indoles 1 with S2Cl2 and DABCO in chloroform gave the corresponding [1,2]dithiolo[4,3-b]indole-3(4H)-thiones 5 by the addition of triethylamine in high yield. 1,2-Dithiole-3-thiones 5 underwent cycloaddition with one or two DMAD equivalents to afford either 2-(3-thioxo-1,3-dihydro-2H-indol-2-ylidene)-1,3-dithioles 10 or fused 4,5-dihydrothiopyrano[3,2-b]indoles 9.