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.     

A new approach to fluorinated 4(3H)-quinazolinones

A new approach for the synthesis of fluorinated 1H-quinazolin-4-ones and 4-substituted quinazolines has been developed. 6-Fluoro-1H-quinazolin-4-ones were obtained by intramolecular cyclization of fluorine-containing S-ethyl N-benzoylisothioureas. Nucleophilic substitution reactions at positions 2 and 7, as well as alkylation at 1-position of quinazolinones were investigated. In addition, the synthesis of fluorine-containing 4-aminoquinazolines was carried out.     

Synthesis of New Fluorinated Derivatives of Quinolinecarboxylic Acids

Ethyl esters of 1-(7-Z-1-ethyl-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carbamoyl)-5-X-6,7,8-trifluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acids (X = H, F; Z = pyrrolidino-, piperidino-, hexamethylenimino-, morpholino-, thiomorpholino-) have been synthesized by the interaction of quinolone-3-carboxylic acid hydrazides with ethyl esters of 3-ethoxy-2-(polyfluorobenzoyl)acrylic acid . It was shown possible to cyclize intramolecularly the esters obtained with the formation of 1,3,4-oxadiazino[6,5,4-i,j]quinoline derivatives.     

Research on benz- and naphthazoles

Heterocyclic analogs of triphenylformazan have been synthesized: 1-(1'-benzylbenzimidazolyl)-3,5-diphenylformazan (I), 1-benzothiazolyl-3,5-diphenylformazan (II), and 1-benzoxazolyl-3,5-diphenylformazan (III). On a basis of the study of IR and UV spectra, the hypothesis has been put forward that I lacks a chelate ring while II and III have chelate rings with a weak intramolecular hydrogen bond. Ease of complex formation with many metals and a capacity for the formation of tetrazolium salts have been noted.For part XXII, see [1].     

Benzazoles and naphthazoles

1-Benzothiazolyl-5-(p-nitrophenyl)formazans, which have thermochromic properties, were synthesized. The structure of the compounds was studied by means of IR and UV spectroscopy and quantum-mechanical calculations, the state of the tautomeric equilibrium was established, and the most probable planar conformations of the formazans as a function of the character of the substituent in the 3-position of the formazan chain were found. It is shown that the thermochromism of these compounds in solution is related to dissociation of the hydrogen of the NH bond of the formazan grouping and that the deeply-colored thermally induced form is the anionic aci form.     

Synthesis and photophysical properties of 2-styrylquinazolin-4-ones

trans-2-Styryl-substituted 3H-, 3-phenyl-, and 3-naphthylquinazolin-4-ones and their 6,7-difluoro derivatives were synthesized by condensation of appropriate 2-methylquinazolin-4-ones with aromatic aldehydes or by the transformation of the heterocycle of 2-methyl-3,1-benzoxazin-4-one under the action of benzylidenephenylamines.     

Synthesis of Fluorinated 1,3,4-Oxadiazino[6,5,4-i,j]quinolines

3-(2-Acylhydrazino)-2-tetra(penta)fluorobenzoylacrylates are readily converted to acylamino-substituted quinolones and, under more forcing conditions, annelation of oxadiazine ring occurs. We have identified the possible cyclization of the mentioned acrylates to 4,5-substituted pyrazoles.     

A Mercury-free Electrode for Determining Amalgam-forming Elements by Stripping Voltammetry

A mercury-free modified screen-printed electrode was proposed for the preconcentration and determination of Cu(II), Pb(II), Cd(II), and Zn(II). The simplicity of design, compactness, and low cost of the developed electrode; the possibility of using it as a disposable electrode; and no need in any operations on the mechanical treatment of the electrode surface make this electrode a candidate for portable transducers in flow and discrete analyses.     

Synthesis of 5-and 7-fluoroquinazolin-4(1<Emphasis Type="Italic">H</Emphasis>)-ones

5-Fluoroquinazoline-2,4-diones and their 2-thio analogs were obtained from 6-fluoroanthranilic acid. Two convenient routes to 5-fluoroquinazolin-4-ones involved cyclocondensation of 6-fluoroanthranilamide with acid chlorides (anhydrides) or with aromatic (heterocyclic) aldehydes. A method for the synthesis of 7-fluoroquinazolin-4-one from 2,4-difluorobenzoic acid was proposed. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1758–1764, September, 2007.