Conversions of 2-thioxo-1,3-dithiol-4,5-dicarboxylic acid dimethyl ester — The path to a new heterocyclic system, (4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2,5,7-trione and 5,6-dimercaptouracil derivatives

The conversions of 2-thioxo-1,3-dithiol-4,5-dicarboxylic acid methyl ester into anhydride, mono- and diamide, and monoamide methyl ester were demonstrated. The new heterocyclic system, (4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2,5,7-trione, was obtained by oxidative rearrangement-cyclization of 2-oxo-1,3-dithiol-4,5-dicarboxylic acid diamide with phenyliodosyl(hydroxy)tosylate and used to synthesize previously unknown 5,6-dimercaptouracil derivatives, including nickel dithiolene complex.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1270–1275, September, 1992.     

The structure of 2-phenylazo-5-(trichloro-1,4-benzoquinonyl)-thiazole

X-ray diffraction crystallographic analysis was used to determine the structure of 2-phenylazo-5-(trichloro- 1,4-benzoquinonyl)thiazole and these results were used to establish that 2-phenylazo-5-(2,5-dihydroxy- 3,4,6-trichlorophenyl)thiazole is formed in the reaction of 3,4,6,7-tetrachloro-2,5-dihydroxy-3 2,3-dihydro-benzo[b]furan with 1-phenylthiosemicarbazide.     

Novel condensed heterocyclic derivatives of benzofuran based on 2,5-dihydroxy-3,4,6,7tetrachloro-2, 3-dihydrobenzo[b]furan

We have synthesized novel condensed heterocyclic derivatives of benzofuran by reaction of 2,5-dihydroxy3, 4, 6, 7-tetrachloro-2, 3-dihydrobenzo[b]furan (I) with 4-phenyl- and 4-methylthiosemicarbazides, diphenylthiocarbazone, and also via cyclization of 2, 5-dihydroxy-4, 6, 7-trichloro-3-(N, N-diethyldithio-carbarnoyl)-2, 3dihydrobenzo[b]furan (obtained in the reaction of benzofuran I with sodium NN-dithiocarbamate).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 463467, April 1996.     

5,7-Dichloro-1,3-dithiolo[4,5-d]pyrimidine-2-thione and -2-Selone: Synthesis, Crystal Structure, Solvatochromism, and Reactions with Nucleophiles

We have obtained for the first time the halo derivatives of a novel heterocyclic system, 1,3-dithiolo[4,5-d]pyrimidine-2-thione and -2-selone, by reaction of 5,7-dioxo(4H,6H)-1,3-dithiolo[4,5-d]pyrimidine-2-thione and -2-selone with POCl₃. The crystal structure of thione confirms that we had obtained the desired compound. The electronic absorption spectra reveal an interesting solvatochromism connected with the appearance of low-intensity n transitions from selenium and sulfur atoms in the visible region of the spectrum. The chlorine atoms in the studied compounds have significant mobility in reactions with nucleophiles (amines, thiourea, azidione), which ensures that new derivatives of 1,3-dithiolo[4,5-d]pyrimidine-2-selone are obtained, and specifically 7-N,N-dialkylamino, 7-N-alkyl-N-arylamino derivatives and 7-isothiuronium salts. The 2-selones obtained can be used in synthesis of new tetrathiafulvalenes.     

Synthesis of 2,5-bis(2-aminothiazol-5-yl)-3,6-dichloro-1,4-benzoquinones

A series of 2-(2-aminothiazol-5-yl)-3,6-dichloro-5-diethylaminoethenyl-1,4-benzoquinones was synthesized from 2-(2-aminothiazol-5-yl)-3,5,6-trichloro-1,4-benzoquinones using acetaldehyde and diethylamine in toluene solution. Refluxing these compounds with substituted thioureas in acetonitrile in the presence of hydrochloric acid gives the corresponding 2,5-bis(2-aminothiazol-5-yl)-3,6-dichlorohydroquinones which can be oxidized to the target products with ferric chloride in aqueous DMF.Riga Technical University, Riga LV-1048, LatviaTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 835–839, June, 2000     

Methods for the Synthesis of Heteroaryl-substituted 1,4-Benzo- and 1,4-Naphthoquinones. (Review)

Methods for the synthesis of heteroaryl-substituted 1,4-benzo- and 1,4-naphthoquinones with a C-C bond between the heterocycle and quinone fragments are reviewed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 803–833, June, 2005.     

Synthesis of [b]-Fused Benzo[d]furano Heterocycles

In the reactions of 3,4,6,7-tetrachloro-2,5-dihydroxy-2,3-dihydrobenzo[b]furan with 4-methyl and 4-phenyl thiosemicarbazides, dithizone and sodium N,N-diethyldithiocarbamate the [b]fused benzo[d]furano heterocycles have been synthesized.