Cyclocondensation of 3-amino-2-iminonaphtho[1,2-d]thiazole with oxalic acid derivatives

Refluxing 3-amino-2-iminonaphtho[1,2-d]thiazole ( 1 ) with diethyl oxalate ( 2a ) in a 2:1 molar ratio in dry pyridine provided 2,2′-binaphtho[1′,2′:4,5]thiazolo[3,2-b][1,2,4]triazole ( 3 ). On the other hand, when 1 was treated with excess amount of 2a in dimethylformamide, it afforded ethyl naphtho[1′,2′:4,5]thiazolo[3,2-b][1,2,4]triazole-2-carboxylate ( 4a ) on heating and ethyl N-(2-iminonaphtho[1,2-d]thiazol-3-yl)oxamate ( 5 ) by stirring at room temperature. Cyclization of 5 upon fusion led to the formation of 3-hydroxy-2H-naphtho-[1′,2′:4,5]thiazolo[3,2-b][1,2,4]triazin-2-one ( 6 ). Compound 6 could also be prepared directly from 1 by refluxing either with 2a neatly, in glacial acetic acid or with oxalic acid ( 2b ) in the same medium. The acid form of 4a might be obtained from 1 and 2b on heating in dimethylformamide, but it was decarboxylated to naphtho-[1′,2′:4,5]thiazolo[3,2-b][1,2,4]triazole ( 4b ) during the reaction.     

Cyclocondensation of chalcones with di- and triamino-1,2,4-triazoles

We have carried out the synthesis of 2-amino-5,7-diaryl-1,2,4-triazolo[1,5-a]pyrimidines from chalcones and 3,4,5-triamino-1,2,4-triazole and synthesized them independently via the 4,7-dihydro derivatives. The course and mechanism of the cyclocondensation are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 938–941, July, 1990.     

Cyclocondensation reaction of a 1,5-diketone with 1,2-diamines

Reaction of 2-acetonyl-4,5-dimethoxy-3′-chlorobenzophenone (1) with ethylenediamine afforded the imidazo[2,1-a]isoquinoline 2, whereas 6-(3-chlorophenyl)-8,9-dimethoxybenzo[b]phenazine (3) and naphthol 4 were obtained with ortho-phenylenediamine.     

Reaction of 1-amino-, 2-amino-, and 1,2-diaminoimidazoles with β-diketones

1,2-Diamino-4-phenylimidazolium perchlorate condenses with 2 mole of β-diketones to give pyrimido[2′,1′:2,3]imidazo[1,5-b]pyridazinium derivatives, while, like 1-amino-2-mercapto-4-phenylimidazole, to give imidazo[1,5-b]pyridazine derivatives. Salts of 1-benzylideneamino- and 1-(2-thiazolyl)-2-aminoimidazoles react with β-diketones to give substituted imidazo[1,2-a]pyrimidinium derivatives.     

Cyclocondensation of α,Β-unsaturated ketones with 3-amino-1,2,4-triazole

Dihydro-1,2,4-triazolo[1,5-a]pyrimidine derivatives were obtained by condensation of 3-amino-1,2,4-triazole with 1,3-diaryl-1-propen-3-ones. The structure of 5-phenyl-7-(4-methylphenyl)-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine was established by x-ray diffraction analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 229–233, February, 1988.     

Cyclocondensation of 2-methylbenzimidazole with acetylacetone

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1695–1696, December, 1989.     

Cyclocondensation reaction of 1,2-diamino-4-methylbenzene and p-substituted acetophenones

1,2-Diamino-4-methylbenzene 1 reacts in the presence of sulphuric acid with 4-substituted acetophenones 2a-e yielding 2,4-diaryl-2,3-dihydro-2,8-dimethyl-1H-1,5-benzodiazepines 3a-e and as minor component 2,4-diaryl-2,3-dihydro-2,7-dimethyl-1H-1,5-benzodiazepines 4a-e . The ratio 3:4 is in the range of 7:3. The structure determination of the regioisomers was performed by NOE measurements.     

Cyclocondensation of N-aryl-3-oxobutanethioamides with 5-amino-3-R-4-R1-pyrazoles

The cyclocondensation products of N-aryl-3-oxobutanethioamides with 5-amino-3-R-4-R¹-pyrazoles are 4-(arylamino)-2-methyl-7-R-8-R¹-pyrazolo[1,5-a]pyrimidine and pyrazolo[1,5-a]pyrimidine-4-thione derivatives, the ratio of which depends on the nucleophilicity of the starting 5-amino-3-R-4-R¹-pyrazoles and the presence of a proton donor solvent. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1550-1555, October, 2008.     

Cyclocondensation of 3-amino-2-hydrazino-4(3H)-pyrimidinones with dimethyl acetylenedicarboxylate. Formation of 1-amino-2,6-dihydro-2,6-dioxo-1H-pyrimido[1,2-b][1,2,4]triazine-3-acetic acid esters

[(1-Amino-6-hydroxy-2(1H)-pyrimidinylidene)hydrazone]butanedioic acid dimethyl esters 3 , formed from 3-amino-2-hydrazino-4(3H)-pyrimidinones and dimethyl acetylenedicarboxylate in acetic acid at room temperature, underwent a facile, thermal rearrangement to 1-amino-2,6-dihydro-2,6-dioxo-1H-pyrimido-[1,2-b]-[1,2,4]triazine-3-acetic acid methyl esters 6 in hot acetic acid.     

Reactions of 3-amino-1-phenyl- and 3-amino-1-(thien-2-yl)-4,4,4-trifluorobut-2-en-1-ones with 1,2-diaminopropane and 1,2-diamino-3,3,3-trifluoropropane

The reactions of 3-amino-1-phenyl-and 3-amino-1-(thien-2-yl)-4,4,4-trifluorobut-2-en-1-ones with 1,2-diaminopropane under kinetically controlled conditions afford mixtures ofcis andtrans isomers of 2-aroylmethyl-4-methyl-2-trifluoromethylimidazolidines. Analogous reactions with 1,2-diamino-3,3,3-trifluoropropane yieldcis-2-aroylmethyl-2,4-bis(trifluoro-methyl)imidazolidines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2135–2139, November, 1999.     

Cyclocondensation of 2-alkoxy-2-isocyanato-3,3,3-trifluoropropionates with primary amines

Cyclocondensation of ethyl 2-alkoxy-2-isocyanato-3,3,3-trifluoropropianates (novel 1,4-bielectrophiles) with primary amines resulted in 5-trifluoromethylimidazolidine-2,4-diones.     

Cyclocondensation of 2-Aminobenzimidazole with Dimedone and Its Arylidene Derivatives

The reactions of 2-aminobenzimidazole with substituted benzaldehydes and dimedone, 2-arylidene derivatives of dimedone, 9-arylhexahydro-1H-xanthene-1,8(2H)-diones and also with dimedone and DMF have been studied. The direction of formation of the pyrimidine ring has been established and discussed. An X-ray structural investigation of 2,2-dimethyl-2,3-dihydrobenzimidazo[1,2-a]quinazolin-4(1H)-one has been carried out.     

Cyclocondensation of 2-hydrazinoperimidine with diethyl oxalate and ethyl pyruvate

Refluxing 2-hydrazinoperimidine (1) with excess amount of diethyl oxalate (2a) gave ethyl 1H-1,2,4-triazolo[4,3-a]perimidine-3-carboxylate (4a) in 84% yield. On the other hand, heating 1 with ethyl pyruvate (2b) in glacial acetic acid afforded 3-methyl-1,2,4-triazino[4,3-a]perimidin-4(1H)-one (6b) in 92% yield. Structures of the products were investigated by spectral and elemental analysis.     

Cyclocondensation of trifluorolactates with isocyanates

Cyclocondensation of trifluorolactates with isocyanates gives 3-substituted 5-trifluoromethyloxazolidine-2,4-diones.     

A new, one-pot, multi-component synthesis of imines of 3-amino-2-arylimidazo[1,2-a]pyridines, 3-amino-2-arylimidazo[1,2-a]pyrazines, and 3-amino-2-arylimidazo[1,2-a]pyrimidines

An efficient, one-pot, multi-component synthesis of 3-amino-2-arylimidazo[1,2-a]pyridines, 3-amino-2-arylimidazo[1,2-a]pyrazines, and 3-amino-2-arylimidazo[1,2-a]pyrimidines is described. Heating a mixture of a 2-aminopyridine, 2-aminopyrazine or 2-aminopyrimidine, a benzaldehyde, and imidazoline-2,4,5-trione under solvent-free conditions afforded imine derivatives of the title compounds in excellent yields. Single-crystal X-ray analysis conclusively confirms the structure of these bridgehead bicyclic 5-6 heterocycles.