Condensed heterocycles with the thiazole nucleus. 17. Thiazolo[4,3-a]-isoquinolinium compounds

3-Methyl-1-phenylthiazolo[4,3-a]isoquinolinium perchlorate, obtained from -chlorobenzylisoquinoline and thioacetamide, has been used to prepare some symmetrical and unsymmetrical cyanine dyes.For Communication 16, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 553–556, April, 1989.     

Condensed heterocycles with a thiazole ring. 1. Thiazolo[3,4-a]pyrimidine derivatives

It is shown that the reaction of 1,3-dicarbonyl compounds or their acetals with 2-methylthio-4-amino-5-phenylthiazolium benzenesulfonate gives 6-methylthiothiazolo[3,4-a]pyrimidinium salts, which react with the appropriate intermediates to give polymethine dyes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 634–638, May, 1982.     

Condensed heterocycles with a thiazole ring. 10. Thiazolo[3,4-b][1,2,4]triazines

Derivatives of a new heterocyclic system, viz., the thiazolo[3,4-b][1,2,4]triazinium ion, were obtained by condensation of cyanobenzyl benzenesulfonate with substituted N-dithiocarboxyhydrazones of 1,2-diketones and -isonitroso ketones.See [1] for communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 498–501, April, 1985.     

Synthesis of condensed heterocycles containing a pyrimido[5,4-e][1,3]-thiazine fragment

The cyclocondensation of 4,6-dichloro-2-methylthiopyridine-5-carbaldehyde and heterocyclic thiones such as 1,2,4-triazole-5-thione, imidazolidine-2-thione, imidazole-2-thione, and 4,5-diphenylimidazole-2-thione in dimethylformamide gave tricyclic heterocycles containing a pyrimido[5,4-e][1,3]thiazine fragment. The reaction of 6-chloro-8-methylthio-5H-pyrimido[5,4-e][1,2,4]triazolo[5,1-b][1,3]thiazin-5-ol with diethylamine, pyrrolidine, and morpholine gave the corresponding 6-dialkylaminopyrimidotriazolothiazines.Vilnius University, 2006 Vilnius, Lithuania; e-mail: sigitas.tumkevicius@chf.vu.lt. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 854–856, June, 2000.     

Synthesis of some new pyrimido[1,6-a]pyrimidines. Isolation of stable covalent hydrated pyrimido[1,6-a]pyrimidines

4-Amino-5-phenylpyrimidine 2 reacts with alkyl malonic acids 3 in acetic anhydride under reflux to give 2(4)H-pyrimido[1,6-a]pyrimidines 4. From these reactions some covalent hydrated pyrimido[1,6-a]pyrimidines 5 were also isolated, where the addition of the water molecule occurred to the 6,7 C = N bond. This covalent hydration is irreversible.     

Condensed heterocycles with a thiazole ring. 16. Cyanine dyes based on thiazolo[3,4-a]pyridinium salts

The reaction of 2-(-chlorobenzyl)pyridines with thioacetamide gave 3-methyl-1-arylthiazolo[3,4-a]pyridinium salts, which form cyanines. It was established that the thiazolopyridinium ring in the dyes has high electron-donor character and a great effective length.See [1] for Communication 15.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1274–1277, September, 1988.     

Condensed heterocycles with a thiazole ring. 2. Monomethylidynecyanine dyes of the thiazolo[3,4-a]pyrimidine series

Unsymmetrical monomethylidynecyanine dyes that contain benzothiazole or quinoline residues were obtained on the basis of thiazolopyrimidine. The energies of the transitions and the electron distributions in the ground, first, and second excited states were calculated for several of the dyes obtained and for model compounds by the self-consistent-field configuration-interaction (SCF CI) method in order to interpret the first absorption bands and determine the localization of the electron transitions.See [1] for communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 639–643, May, 1982.     

Condensed heterocycles with a thiazole ring.

Derivatives of new condensed heterocyclic systems — pyrido- and quinolino[1,2:3,2]thiazolo[4,5-b]pyrazines — were synthesized by condensation of 2,3-dichloropyrazine with 2-mercaptopyridine and 2-mercaptoquinolines.See [1] for Communicaton 17.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1276–1278, September, 1990.     

Synthesis of some new pyrimido[1,6-a]pyrimidines

4-Amino-5-arylpyrimidines 1 react with diethyl alkylmalonates 2 to give pyrimido[1,6-a]pyrimidines 4 in satisfactory yields. A possible mechanistic scheme and the spectral data of the reaction products are discussed.     

A new synthesis of pyrimido[5,4-e]-as-triazine 4-oxides and their ring transformation to pyrrolo[3,2-d]pyrimidines

A new synthesis of certain pyrimido[5,4-e]-as-triazine 4-oxides and their ring transformation to pyrrolo-[3,2-d]pyrimidines by the 1,3-dipolar cycloaddition reaction is described. Thus, reaction of 6-hydrazino-1,3-dimethyluracil ( 1 ) with triethyl orthoformate gave 6-ethoxymethylenehydrazino-1,3-dimethyluracil ( 2 ). Treatment of 2 with arylamines gave 6-arylaminomethylenehydrazino-1,3-dimethyluracils ( 3a-e ). Nitrosative cyclization of 3a-e with sodium nitrite afforded 3-arylaminofervenulin 4-oxides ( 6a-e ). Reaction of 6a-e with acetylenic esters yielded 7-alkoxycarbonyl-6-arylamino-1,3-dimethylpyrrolo[3,2-d]pyrimidine-2,4(1H,3H-diones ( 15a-e and 16 ).     

Synthesis of substituted furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines and furo[3,2-e]tetrazolo[1,5-c]pyrimidines

A series of substituted furo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidines and furo[3,2-e]tetrazolo[1,5-c]pyrimidines were obtained from reactions of substituted 2-dimemylamino-4-hydrazmofuro[2,3-d]pyrimidines with orthoesters or sodium nitrite in acetic acid, respectively.     

Condensed Pyridopyrimidines. 7. Synthesis of Condensed Triazolo[4,3-c]- and Tetrazolo[1,5-c]pyrimidines

Novel dihydro-5H-pyrano[3',4':5',6']pyrido[2,3-d]-1,2,4-triazolo[4,3-c]pyrimidines and 1,2,3,4-tetrazolo[1,5-c]pyrimidines have been synthesized from 2-amino-3-cyano-7,7-dimethyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine.     

Condensed heterocyclic systems with a thiazole ring. 11. Thiazolo [3,4-b]-1,2, 4-triazinones

Syntheses are reported for substituted 2-oxo-1,2-dihydrothiazolo[3,4-b]-1,2,4-triazinium salts. The action of bases on these salts leads to the corresponding mesoionic compounds.For communication 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1497–1500, November, 1985.