Thiazolo pyrimidine-5,7-dione

Thiazolo[5,4-d]pyrimidine, 2,5,7-trichloro-nucleopfulic substitution, 6, 686 Thiazolo[3,2-a]pyrimidine-5,7-diones IR spectra, 6, 672 Thiazolopyrimidines synthesis, 5, 572, 574, 578 Thiazolopyrimidines, amino-purine synthesis from, 5, 591 Thi azolo[3,2-ajpyrimidines synthesis... 

The reaction of 2-mercapto-4-(2, 4 -dichlorophenyl)-5-cyanopyrimidin-6(l//)one 421 (obtained by stirring ethyl cyanoacetate and thiourea with 2,4-dichlorobenzaldehyde in sodium ethylate at room temperature, in 70% yield), with a solution of monochloroacetic acid and />-cholorobenzaldehyde in glacial acetic acid, in the presence of sodium acetate, affords 2-[(/>-chlorophenyl)methylene]-6-cyano-7-(2, 4 -dichlorophenyl)thiazolo[3,2-tf]pyrimidin-3,5-dione 422. Finally, the reaction of compound 422 with hydrazine hydrate converts it into product 423 (Scheme 49) < 1996PS( 116)39>. 

Thiazolo[3,2-a]pyrimidines-5,7-dione (86), refluxed with DMAD for 20 hours in chloroform, gave 65% of the pyridothiazole 87 by elimination of ethyl isocyanate.612... 

Three methods were reported to obtain the title compounds. The first was based on a reaction sequence starting from 5,6-diamino-4-thiouracil-sodium salt, alkylation with 1,2-dibromoethane to 7,8-diamino-2,3-dihydro-5//-thiazolo-[3,2-c]pyrimidine (135) and fusion with urea or thiourea under formation of a third ring to the respective 7,8-dihydrothiazolo[2,3-/]purine-2,5(l//,3//)-dione (136) and 2,3,7,8-tetrahydro-2-thioxothiazolo[2,3- ]purin-5(l//)-one (137) (92FES1315) (Scheme 37). 

The following examples illustrate the scope of this reaction 3-aminopyr-role-2-carboxamide to a pyrrolo[3,2-d]pyrimidine-2,4-dione205 2-amino(IV-alkyl)benzamides to 3-alkyl-2,4-quinazoline-2,4-diones266 5-aminothiazole-4-carboxamide to thiazolo[5,4-d]pyrimidine-2,4-dione (see 149)236 4-aminoimidazole-5-carboxamide (and derivatives) to purine-2,6-diones (see... 

Cycloaddition and cyclization routes were used to access certain 1,3-diazines. The 4+2 cycloaddition reaction of 4-(N-allyl-N-aryl)amino-l,3-diaza-l,3-butadienes with vinyl-, isopropenyl-, and chloroketene led to pyrimidinone-fused pyrimidinones <97T13841>. Cis-cyclopenta[d]pyrimidines were derived from cis-2-amino-l-cyclopentanecarboxylates by cyclization with KOCN and KSCN <97JHC1211>. 2-Thioxopyrido[3, 2 4,5]thieno[3,2-r/]pyrimidin-4(3//)-ones 19 were prepared by cyclocondensation of 2-carbethoxy-3-amino-4-phenyl-6-substituted-thieno[2,3-/)]pyridines and isothiocyanates <97JHC937>. Thiazolyl-benzimidazoles derived from 2-cyanomethyl-l//-benzimidazole and 2,3-dihydrothiazole-2-(3//)-thiones were cyclized to the corresponding thiazolo[4,5-r/]pyrimidines <97PHA346>. Reductive cyclization of 6-cyanomethyl-5-nitropyrimidines afforded 7-alkyl-5//-pyrrolo[3,2-r/]pyrimidines and 6-amino-7,7-dialkyl-7//-pyrrolo[3,2-rf]pyrimidines <97T391>. 7-Methyl-5-alkyl-2-vinyl-pyrazolo[3,4-r/]pyrimidine-4,6(5//,7//)-diones arose from cyclization and alkylation of... 

Solid-Phase Synthesis of 2,4,6-Trisubstituted Thiazolo[4,5-(/]pyrimidine-5,7-diones... 

P. Singh, K. Kumari, M. Dubey, V.K. Vishvakarma, G.K. Mehrotra, N.D. Pandey, R. Chandra, Ionic liquid catalyzed synthesis of 7-phenyl-l,4,6,7-tetrahydro-thiazolo[5,4-d]pyrimidine-2,5-diones, C. R. Chim. 15 (2012) 504-510. 

Abu-Zied reported the synthesis of 2-aiylidine-thiazolo[2,3-d]pyrimidine-3(3H),5(5H)-dione 16 (Scheme 6) by the reaction of a ternary mixture of 2-thioxo-thieno[2,3-d]pyrimidin-4(4H)-one 15, chloroacetic acid, and 4-chlorobenzaldehyde[24]. 

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