4-Hydroxy-2-quinolones. 118. Synthesis,structure, and chemical properties of 2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo-[3,2-<Emphasis Type="Italic">a</Emphasis>]quinoline-4-carboxylic acid and its ethyl ester

Bromination of N-allyl-substituted 4-hydroxy-2-quinolinones with molecular bromine in acetic acid or carbon tetrachloride occurs with closing of a five membered oxazole ring to give 2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo[3,2-a]quinoline. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 736–749, May, 2007.     

4-hydroxy-2-quinolones. 124. Synthesis and structure of ethyl 2-bromomethyl-5-oxo-1,2,6,7,8,9-hexahydro-5H-oxazolo-[3,2-<Emphasis Type="Italic">a</Emphasis>]quinoline-4-carboxylate

The hydrogenation of the benzene part of the molecule in N-allyl-substituted 4-hydroxy-2-quinolinones does not affect the nature of their bromination by molecular bromine and gives 2-bromomethyl-5-oxo-1,2,6,7,8,9-hexahydro-5H-oxazolo[3,2-a]quinolines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1180–1188, August, 2007.     

4-Hydroxy-2-quinolones 123. Amidation of 2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]-quinoline-4-carboxylic acid

The reaction of 2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo[3,2-a]quinoline-4-carboxylic acid with thionyl chloride is accompanied by a transformation of the oxazoloquinolone ring to give 4-chloro-1-(2,3-dichloropropyl)-2-oxo-1,2-dihydroquinoline-3-carboxylic acid chloride. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1034–1042, July, 2007.     

Trifluoroacetylation of pyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrazines

A study was carried out on the reaction of pyrrolo[1,2-a]pyrazines containing an alkyl, aryl, or aralkyl substituent at C-1 with trifluoroacetic anhydride. Trifluoroacetylation products may be formed either by reaction in the pyrrole ring or at the aryl or aralkyl groups at C-1. Products of electrophilic substitution at C-6 are formed in the trifluoroacetylation of pyrrolo[1,2-a]pyrazines containing at C-1 a substituent bulkier than a methyl group but lacking substituents at C-6 (the α-position of the pyrrole ring). __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1226–1233, August, 2007.     

4-Hydroxy-2-quinolinones 128. Bromination of N-allyl-4-hydroxy-2-oxo-1,2-dihydroquinolines and pyridines unsubstituted in position 3

Bromination of N-allyl-4-hydroxy-2-oxo-1,2-dihydroquinoline and N-allyl-5-ethoxycarbonyl-4-hydroxy-6-methyl-2-oxo-1,2-dihydropyridine is accompanied not only by closing of a five membered oxazole ring but also by a second bromination of the 2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo[3,2-a]-derivatives formed at position 4. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1365–1373, September, 2007.     

Nitration of Pyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrazines

We have synthesized nitro derivatives of pyrrolo[1,2-a]pyrazines using a nitrating mixture and acetyl nitrate. We have obtained the products of oxidation of the side chain of 1,6-substituted pyrrolo[1,2-a]-pyrazines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1579–1586, October, 2005.     

Phase-transfer catalytic synthesis and hypocholesterolemic activity of thiazino[3,2-<Emphasis Type="Italic">a</Emphasis>]benzimidazole and its silicon analog

The reaction of 2-mercaptobenzimidazole with 1,3-dichloropropane or bis(chloromethyl)dimethylsilane in the two-phase catalytic system of solid K₂CO₃-18-crown-6-toluene at 111°C leads to a selective formation of tricyclic benzimidazole sulfides in 56 and 92% yields. The synthesized compounds were tested as hypocholesterolemic agents. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 274–279, February, 2007.     

11H-isoindolo[2,1-<Emphasis Type="Italic">a</Emphasis>]benzimidazoles (Review)

Data on methods for the synthesis of isoindolo[2,1-a]benzimidazole and its derivatives and their chemical characteristics are reviewed. Data from quantum-chemical calculations of certain structures are presented. Possible practical applications of the compounds are indicated. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 323–351, March, 2007.     

Transformations of 8-substituted tetrazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrazines

The reactions of 8-chlorotetrazolo[1,5-a]pyrazine with N-, O-, and S-nucleophiles involve the ipso substitution of the chlorine atom. Heating of this compound with benzotriazole or phenyltetrazole results in elimination of the nitrogen molecule from one of the tetrazole rings to form new annelated azapentalenes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 334–338, February, 2007.     

Synthesis and properties of pyrimido[4,5-<Emphasis Type="Italic">a</Emphasis>]- and pyrido[4,3-<Emphasis Type="Italic">a</Emphasis>]carbazole derivatives

Methods for the synthesis of substituted pyrimido [4,5-a]- and pyrido[4,3-a]carbazoles were proposed. Condensation of 2-(dimethylaminomethylene)-6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-one with guanidine and thiourea afforded 2-amino-8-methyl-6,11-dihydro-5H-pyrimido[4,5-a]carbazole and 8-methyl-3,5,6,11-tetrahydro-2H-pyrimido[4,5-a]carbazole-2-thione, respectively. The reaction of cyano(6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-ylidene)acetamide with dimethylformamide dimethyl acetal gave N-(dimethylamino-methylene)cyano(6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-ylidene)acetamide. Cyclization of the latter yielded 1-cyano-8-methyl-3,5,6,11-tetrahydro-2H-pyrido[4,3-a]carbazol-2-one.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2740–2744, December, 2004.     

Stereoselective synthesis of 4-substituted 1,2,3,4,10,10a-hexahydropyrazino[1,2-<Emphasis Type="Italic">a</Emphasis>]indoles

4-Substituted 1,2,3,4-tetrahydropyrazino[1,2-a]indoles were synthesized from 2-cyanoindole. (R)-4-Methyl-1,2,3,4-tetrahydropyrazino[1,2-a]indole was obtained by the Mitsunobu reaction. Stereoselective reduction of 4-substituted 1,2,3,4-tetrahydropyrazino[1,2-a]indoles gave 4-substituted 1,2,3,4,10,10a-hexahydropyrazino[1,2-a]indoles. (4R, 10aR)-4-Methyl-1,2,3,4,10,10a-hexahydropyrazino[1,2-a]indole was synthesized.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 221–225, January, 2005.     

Transformation of indoline spiropyrans to bridged 1,3-benzoxazepino[3,2-<Emphasis Type="Italic">a</Emphasis>]indoles <Emphasis Type="Italic">via</Emphasis> carbanions stabilized by a cyano group

Condensation of 1-cyanomethyl-2,3,3-trimethyl-3H-indolium perchlorate with ortho-hydroxy-substituted aromatic aldehydes afforded 1-cyanomethylindoline spiropyrans. The latter underwent rearrangement to bridged 1,3-benzoxazepino[3,2-a]indoles on treatment with a base. The mechanism of the rearrangement includes generation of a carbanion stabilized by a cyano group. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1322–1328, September, 2007.     

4-Hydroxy-2-quinolones 144. Alkyl-, arylalkyl-, and arylamides of 2-hydroxy-4-oxo-4H-pyrido[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-3-carboxylic acid and their diuretic properties

Alkyl-, arylalkyl-, and arylamides of 2-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid were prepared with a view to establishing a structure-biological activity relationship. A comparative analysis has been made of their diuretic properties and those of the structurally similar 4-hydroxy-2-oxo-1,2-dihydroquinoline-3-carboxamides. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 718–729, May, 2008.     

4-Hydroxy-2-quinolones 139. Synthesis,structure, and antiviral activity of N-R-amides of 2-hydroxy-4-oxo-4H-pyrido[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-3-carboxylic acids

Dialkylaminoalkylamides of 2-hydroxy-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acids have been obtained as potential antiviral agents. The special features of the spatial structure of one example of the synthesized compounds have been studied. Results are given of the investigation of cytotoxicity and antiviral activity in relation to type 1 herpes virus and coronavirus. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 61–77, January, 2008.     

Fluorine-containing pyrido[1,2-<Emphasis Type="Italic">a</Emphasis>]quinazolin-6-ones

Reactions of 2-aminopyridine and 2-amino-5-methylpyridine with 2,3,4,5-tetrafluorobenzoyl chloride afforded N,N’-diaroylpyridinium salts, which were converted into 6H-pyrido[1,2-a]quinazolin-6-ones by refluxing in toluene in the presence of triethylamine. The angular structure of the tricyclic derivatives obtained was confirmed by ¹⁹F and ¹³C NMR spectroscopy and 2D heteronuclear HetCOR and HMBC experiments.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2216–2220, October, 2004.     

4-Hydroxy-2-quinolones 141. Synthesis and structure of 5R-3-hydroxy-1,5-dihydropyrazolo[4,3-<Emphasis Type="Italic">c</Emphasis>]quinolin-4-ones

Treatment of 1R-4-chloro-3-ethoxycarbonyl-2-oxo-1,2-dihydroquinolines with p-toluenesulfonylhydrazide in refluxing ethanol and in the presence of triethylamine gives the 3-hydroxy-5R-1,5-dihydropyrazolo[4,3-c]quinolin-4-ones. The possible mechanism of formation, features of the steric structure of the synthesized compounds, and their NMR and mass spectra are discussed. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 233–238, February, 2008.