Alexander V. Borisov

Novel Aspects of the Reaction of 3-(Benzimidazol-2-yl)-2-iminocoumarins with Aromatic Aldehydes

The reaction of 3-(benzimidazol-2-yl)-2-iminocoumarins with aromatic aldehydes has been studied. The condensation products 7-aryl-7H-benzo[4,5]imidazo[1,2-c]benzopyrano[3,2-e]pyrimidines or 3-(benzimidazol-2-yl)coumarins are formed depending on the nature of the substituent in the starting 2-iminocoumarin and aldehyde. In DMF medium, 7-aryl-7H-benzo[4,5]imidazo[1,2-c]benzopyrano[3,2-e]pyrimidines isomerize to the corresponding 7-aryl-14H-benzo[4,5]imidazo[1,2-c]benzopyrano[3,2-e]pyrimidines. The effect of the substituent on the isomerization process has been studied and the reaction mechanisms are discussed.

Reactions of 3-(4-Aryl-2-thiazolyl)- and 3-(2-Benzothiazolyl)-2-iminocoumarins with N-Nucleophiles

The reaction of 3-(4-aryl-2-thiazolyl)- and 3-(2-benzothiazolyl)-2-iminocoumarins with N-nucleophiles was studied. This reaction gives 2-N-substituted 3-(4-aryl-2-thiazolyl)- and 3-(2-benzothiazolyl)iminocourmarins. N-Nucleophiles such as arylamines, heterocyclic amines, and hydrazine derivatives undergo this reaction.

Multicomponent Reaction of 2-aminobenzimidazole, Arylglyoxals, and 1,3-cyclohexanedione

n Three-component reactions of 2-aminobenzimidazole with arylglyoxals and 1,3-cyclohexanedione have been studied under conventional heating and microwave irradiation. Different product types including the Michael adduct and fused heterocyclic systems were obtained. Conditions for the selective formation of 12-aroylbenzimidazo[2,1-b]quinazolin-1(2H)-ones and 3-oxo-2-(2-aryl-1H-imidazo[1,2-a]-benzimidazol-9-ium-3-yl)cyclohex-1-enolates have been determined. The structures of all compound types were established by an X-ray diffraction study.

Parallel Liquid-Phase Synthesis of 5-(1H-4-Pyrazolyl)-[1,2,4]oxadiazole Libraries

Combinatorial libraries of substituted 3-(methylthio)-5-(amino)-4-([1,2,4]oxadiazol-5-yl)-1H-pyrazoles 6, 10, 13, 15 (395 members, yields 32-87%), 4-([1,2,4]oxadiazol-5-yl)-1H-3,5-pyrazolediamines 8, 11 (571 members, yields 25-83%), 2-(methylthio)-3-([1,2,4]oxadiazol-5-yl)pyrazolo[1,5-a]pyrimidin-7(4H)-ones 17 (85 members, yields 56-95%), and 2-(amino)-3-([1,2,4]oxadiazol-5-yl)pyrazolo[1,5-a]pyrimidin-7(4H)-ones 18 (110 members, yields 56-95%) were synthesized by the parallel liquid-phase synthesis method.

New Series of Dyes for Flashlamp-Excited Lasers

A new series of laser compounds which are derivatives of 7H-benzo[4, 5]imidazo[1, 2-c]chromeno[3, 2–e]pyrimidine have been developed and their working characteristics are presented. It is shown that the new compounds fluoresce with a high quantum yield (0.83–0.97) in the green spectral region; their methanol solutions gave effective lasing upon flashlamp excitation with a pulse duration of about 2.0 μsec at the level 0.5. In a nonselective cavity they emit laser radiation in the range 540–570 nm. The influence of the molecular structure of the investigated dyes on their fluorescence and laser characteristics is discussed.

THREE-COMPONENT SYNTHESIS OF 4-AROYL- 2(1),4,5,7-TETRAHYDROPYRAZOLO(3,4-b)PYRIDIN-6-ONES AND THEIR PROPERTIES

Inspired by the concept of multicomponent reactions, a novel one-pot synthesis involving arylglyoxals, 5-aminopyrazoles, and Meldrums acid has been developed and employed for the creation of a small library of 4-aroyl-2(1),4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-ones. The alkylation, acylation, reduction, and oxidation reactions of 4-aroyl-3-methyl-2,4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-ones have been studied.

The synthesis of low molecular weight pyrrolo[2,3-c]pyridine-7-one scaffold

A facile method for the synthesis of substituted pyrrolo[2,3-c]pyridine-7-ones is developed that applies an acid-promoted intramolecular cyclization of 2-pyrrolecarboxylic acid amidoacetals as key step. The synthesis is easily scaled up to 1.5xa0mol quantity with no yield decrease. The alkylation/arylation reaction of the pyrrolo[2,3-c]pyridine-7-ones proceeds regioselectively giving N6-substituted derivatives.

Synthesis of 1,6-diamino-2-imino-2,3-dihydropyrimidin-4(1Н)-one and preliminary study of its two- and three-component reactions

n A new heterocyclic compound, 1,6-diamino-2-imino-2,3-dihydropyrimidin-4(1H)-one, was synthesized for the first time and some of its chemical properties were studied. This pyrimidinone showed very unusual reactivity comparing to analogous compounds in reactions with alkylating and acylating agents and in other two-component reactions. Three-component reactions involving 1,6-diamino-2-imino-2,3-dihydropyrimidin-4(1H)-one were also explored.

Synthesis of brand-new 1,6-diamino-2-iminopyrimidin-4(1H)-one and preliminary study of its two- and three-component reactions

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Novel approach for the synthesis of N-unsubstituted 2,3,5,6-tetrahydro-4H-2,6-methano-1,3-benzoxazocine-4-thiones

An efficient one-pot method for the synthesis of 2,3,5,6-tetrahydro-4H-2,6-methano-1,3-benzoxazocine-4-thiones in high yields has been developed via regioselective tandem reaction of coumarin-3-thioamides and ketones containing different methylene groups. Further oxidation with hydrogen peroxide under basic conditions leads to the formation of N-unsubstituted derivatives of 2,3,5,6-tetrahydro-4H-2,6-methano-1,3-benzoxazocin-4-one.