Synthesis and antimycobacterial activity of purine conjugates with (S)-lysine and (S)-ornithine

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High-Power CO2 Laser System with Repetition Rate Operation for High Current Multicharged Heavy Ion Generations

Experimental and numerical calculation results devoted to development of an optical system for an ion source based on a repetition rate CO₂ laser are described. The laser chain consists of a master oscillator, gas absorber cells, and a four-pass amplifier. The optical system provides smooth laser pulses with variable duration and high spatial quality that ensures efficiency for plasma heating and ion generation. The parameters of the plasma ion component measured in the CERN laboratory are applied for a lead target illumination.     

Cyclization of N-alkyl azinium cations with bifunctional nucleophiles. 21. Regioisomeric 1,3,4-thiadiazino[5,6-b]quinoxalines

Thiobenzhydrazides undergo cyclization with N-alkyl-quinoxalinium salts to give 5-alkyl-substituted 1,4,4a,5,10,10a-hexahydro-1,3,4-thiadiazino[5,6-b]quinoxalines, which undergo isomerization to 10-alkyl-substituted thiadiazinoquinoxalines when they are heated in ethanol or in the presence of acids.See [1] for Communication 20.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 557–561, April, 1987.     

Unusual transformation of a fluoroalkyl-containing β-aminovinyl ketone

Russian Chemical Bulletin -     

Imidazoline ring cleavage in 1,3,6,10-tetraazatetracyclo-[7.3.1.02,7.06,13]trideca-4, 11-dienes,leading to the formation of diquinoxalino[1,2-a∶2′,3′-d]pyrrole derivatives

Dibenzo[d,k]-1,3,6,10-tetraazatetracyclo[7.3.1.0^2,7.0^6,13]trideca-4,11-dienes undergo addition reactions at the C₍₂₎ carbon atom with alcohols and thiols, accompanied by cleavage of the C-N bond of the imidazoline ring, to generate diquinoxalino[1,2-a2,3-d]pyrrole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 513–522, April, 1987.     

Fluorinated benzimidazo[1,2-a]quinolones

The reactions of 2-cyanomethylbenzimidazole with polyfluorobenzoyl chlorides afforded 2-(1,3-dihydrobenzimidazol-2-ylidene)-3-oxo-3-polyfluorophenylpropionitriles. Refluxing of the latter compounds in acetonitrile in the presence of DBU or in dimethylformamide in the presence of amines gave rise to fluorine-containing derivatives of benzimidazo[1,2-a]quinolone.     

Cyclization of n-alkylazinium cations with bisnucleophiles. 4. Regio- and stereospecificity of the reactions of β-diketones with quinoxalinium salts and their aza and benzo analogs

The reactions of substituted quinoxalinium, benzo[g]- and benzo[f]quinoxalinium, and pyrido[2,3-b]pyrazinium salts with anions of -dicarbonyl compounds give furo[2,3-b]-annelated systems with strictly determined regio- and stereoorientations.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1543–1548, November, 1981.     

Fluorine-containing Heterocycles: XI. 5(6)-Fluoro-6(5)-X-benzofuroxans: Synthesis, Tautomerism, and Transformations

Features of 5(6)-fluoro-6(5)-X-benzofuroxans tautomerism were investigated. By ¹H, ¹³C, and ¹⁹F NMR spectroscopy the direction of Boulton-Katritzky rearrangement in nitration, nitrosation, and azo coupling of fluorine-containing furoxanes was determined.     

Kinetic resolution of heterocyclic amines by reaction with optically active acid chlorides. The effect of reaction conditions on the diastereoselectivity of acylation of (±)-3-methyl-2,3-dihydro-4H-1,4-benzoxazine

The influence of the reaction conditions (solvent, base) on the diastereoselectivity of acylation of (±)-3-methyl-2,3-dihydro-4H-1,4-benzoxazine with (S)-naproxen and N-tosyl-(S)-proline chlorides was studied. The highest diastereoselectivity was observed for the reaction carried out in benzene in the presence of aliphatic tertiary amines.