By fusing methyl picolinate with phenacyl bromides, the corresponding phenacyl salts were obtained, cyclization of which in acetic anhydride led to previously undescribed 3-aryl-1H-pyrido[2,1-c][1,4]oxazinium bromides. Reduction of the quaternary salts of methyl picolinate followed by acid hydrolysis leads to the alkaloid DL-baikiain.

A method has been developed for the synthesis of a new 18-membered nitrogen macroheterocycle via acid-catalyzed cyclocondensation of 1-[(2E,Z)-2-hydrazinylidene-2-phenylethyl]-5-methyl-1H-pyrazole-3-carbohydrazide which was obtained by hydrazinolysis of methyl 5-methyl-1-(2-oxo-2-phenylethyl)-1H-pyra­zole-3-carboxylate.

Ethyl 3-phenyl-1H-pyrazole-5-carboxylate reacted with oxiranes to give mixtures of 2-phenyl-6-R-6,7-dihydro-4H-pyrazolo[5,1-c][1,4]oxazin-4-ones and ethyl 1-(2-hydroxy-3-R-propyl)-5-phenyl-1H-pyrazole-3-carboxylates. A probable mechanism for the formation of fused oxazine ring has been proposed.

The reaction of nicotinic acid ethyl ester with phenacyl bromides containing electron-donating substituents in the benzene ring afforded the corresponding quaternary pyridinium salts which were reduced with sodium tetrahydridoborate to ethyl 1-(2-aryl-2-hydroxyethyl)-1,2,5,6-tetrahydropyridine-3-carboxylates, and acid hydrolysis of the latter involved cleavage of the exocyclic C–N bond with the formation of guvacine in 76–93% yield. Analogous imidazo[4,5-c]pyridine and β-carboline derivatives containing a guvacine fragment were synthesized following a similar reaction sequence.

Предложен метод синтеза 3-фенил-1 H -[1,4]оксазино[4,3- a ]бензимидазол-1-она -первого представителя новой гетероциклической системы бензимидазоло-α-пиронов и изучено его превращение в 4-фенил-2,5-дигидро-1 H -[1,2,5]триазепино[5,4- a ]бензимидазол-1-он в реакции с гидразингидратом.

A synthetic route has been proposed to 3-phenyl-1H-[1,4]oxazino[4,3-a]benzimidazol-1-one, which is the first representative of a new heterocyclic system. The transformation of the title compound to 4-phenyl-2,5-dihydro-1H-[1,2,5]triazepino[5,4-a]benzimidazol-1-one via reaction with hydrazine hydrate has been studied.

A modified procedure has been proposed for the synthesis of 2,7-diphenyl-5,8-dihydro-4 H -pyrazolo[5,1- d ][1,2,5]triazepin-4-one, and the possibility of transformation of the latter to the pyrazolo[1,5- a ]pyrazine system has been demonstrated. Functionalization of 2,7-diphenyl-5,8-dihydro-4 H -pyrazolo[5,1- d ][1,2,5]triazepin-4-one at the 4-position and fusion of a tetrazole or triazole ring at the C 4 –N 5 bond have been performed.

A synthetic approach to β-carbolines has been proposed on the basis of heterocyclization of ethyl 2-(2-benzoyl-1 H -indol-3-yl)acetate with N -methylformamide or ammonium acetate. Hydrazine hydrate proved to be inefficient in this reaction. The heterocyclization of dimethyl 2,2′-(2-benzoyl-1 H -indole-1,3-diyl)diacetate with ammonium acetate selectively afforded 2-(3-hydroxy-1-phenyl-9 H -pyrido[3,4- b ]indol-9-yl)acetamide. Treatment of dimethyl 2,2′-(2-benzoyl-1 H -indole-1,3-diyl)diacetate with hydrazine hydrate, followed by acid-catalyzed heterocyclization, gave methyl 2-(4-oxo-1-phenyl-4,5-dihydro-3 H -[1,2,5]triazepino[5,4- a ]indol-11-yl)acetate or 2-{4-oxo-1-phenyl-4,5-dihydro[1,2]diazepino[4,5- b ]indol-10(3 H )-yl}acetohydrazide, depending on the conditions.

Предложен метод синтеза неизвестных ранее пирроло- и индоло-1,4-эпокси[1,4]оксазепинов на основе реакции эпоксиметилирования 2-бензоилпиррола и 2-бензоилиндола. Изучены пути возможных трансформаций продуктов эпоксиметилирования.

A new procedure has been proposed for the synthesis of previously unknown pyrrolo- and indolo-1,4-epoxy[1,4]oxazepines by epoxymethylation of 2-benzoyl-1H-pyrrole and 2-benzoyl-1H-indoles with epichlorohydrin. Some transformations of the epoxymethylation products have been studied.

3,4-Dihydropyrimidines obtained by the Biginelli reaction react with hydrazine to give a mixture of N-[(3,5-dimethyl-1H-pyrazol-4-yl)(R)methyl]ureas and 4-R-3,7a-dimethyl-1,3a,4,5,7,7a-hexahydro-6H-pyrazolo[3,4-d]pyrimidin-6-ones. The latter transform into N-[(3,5-dimethyl-1H-pyrazol-4-yl)(R)methyl]ureas in an acidic medium.

AbstractThe base‐mediated aminomethylation of 6‐amino‐4‐aryl‐2‐thioxo‐1,2‐dihydropyridine‐3,5‐dicarbonitriles (I) provides access to pyridotriazine and tetrazocine derivatives in ratios depending strongly on the structure of the initial amine, the ratio of regents, and the reaction conditions.

Precarbene and metalcarbene compounds of a series of imidazole have been synthesized to study their antimicrobial activity. Calix[4]arene imidazolium salts 3,4a,b have been obtained from the corresponding chloromethyl derivatives of calix[4]arenes and N-substituted imidazoles in dimethylformamide or tetrahydrofuran, and salt 5 – from p-xylylenediimidazoles and 1-bromoadamantane in o-dichlorobenzene. Monocarbene complexes of palladium 8a-c, copper(I) 8d and biscarbene complexes of nickel 9a and cobalt 9b have been synthesized by the direct interaction of stable carbenes with transition metal salts or by the analogous reactions in situ in tetrahydrofuran. The NMR spectra data of the compounds synthesized are given. The most characteristic signals of the carbenoid carbon atoms are detected in the 13С NMR spectra of complexes 8a-d, 9a in the range of 165-178 ppm. A high antimicrobial activity has been found for carbenoid salts 4a,b, 5 on the test-culture of M. Luteum. It corresponds to the minimal bacteriostatic concentration (MBsC) of 15.6 mkg/mL and the minimal bactericidal concentration (MBcC) of 62.5 mkg/mL for compound 2. The higher activity has been found for carbene complexes of nickel 9a and cobalt 9b on the test-culture of M. luteum (MBsC is 7.8 mkg/mL and MBcC is 15.6 mkg/mL), and the highest 9b on the test-cultures of M. luteum and C. tenuis (the minimal fungistatic concentration is 1.9 mkg/mL and the minimal fungicidal concentration is 3.9 mkg/mL).

The aminomethylation of 6-amino-4-aryl-2-thioxo-1,2-dihydropyridine-3,5-dicarbonitriles by the action of primary amines and an excess of formaldehyde under conditions of base catalysis was studied. It was found that the structure and yields of the products depend largely on the structure of the initial amine and also on the ratio of the reagents and reaction conditions. In the case of alkyl- or arylalkylamines, 8-aryl-3-alkyl(arylalkyl)-6-thioxo-1,3,4,6-tetrahydro-2H-pyrido[1,2-a][1,3,5]triazine-7,9-dicarbonitriles were obtained, whereas when aromatic amines were used 3,10-diaryl-1,8-dithioxo-5,6,12,13-tetrahydro-1H,8H-dipyrido[1,2-a:1′,2′-e][1,3,5,7]tetrazocine-2,4,9,11-tetracarbonitriles or their mixtures with the above-mentioned pyrido[1,2-a][1,3,5]triazines were obtained. Dipyrido[1,2-a:1′2′-e]-[1,3,5,7]tetrazocine derivatives were also synthesized by direct condensation of 6-amino-4-aryl-2-thioxo-1,2-dihydro-pyridine-3,5-dicarbonitriles with formaldehyde.

Carbene complexes of nickel, palladium, and copper(I) effectively catalyze the reduction of aromatic ketones under the influence of 2-propanol in the presence of potassium hydroxide. Bis(1,3-dimethylbenzimidazol-2-ylidene)copper(I) iodide and the polymeric complex of crown-biscarbene with copper(I) iodide show the highest catalytic efficiency.

The effect of acetylacetone and ammonia in urea-formaldehyde resins on the reactions occurring in their presence was examined. The formation of 2,6-dimethyl-3,5-diacetyl-l,4-dihydropyridine in urea-formaldehyde resins was confirmed by 1 H NMR spectroscopy.

A new stable crystalline carbene, 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, was synthesized by decomposition of 1,3-bis(1-adamantyl)-2,3-dihydro-1H-benzimidazol-2-ylacetonitrile on heating under reduced pressure. Heteroaromatic 1,3-R2-disubstituted benzimidazol-2-ylidenes, both stable (R = 1-Ad) and generated in situ (R = Me, Bzl), as well as 1,3,4,5-tetraphenylimidazol-2-ylidene (generated in situ), reacted with acetonitrile to give the corresponding insertion products, 1,3-disubstituted 2-cyanomethyl-2,3-dihidro-1H-(benz)-imidazoles. The geometric parameters of 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, determined by X-ray analysis, suggest its lower aromaticity as compared to imidazol-2-ylidenes and 1,2,4-triazol-5-ylidenes. The structures of 2-cyanomethyl-2,3-dihydro-1H-benzimidazoles, 2-cyanomethyl-1,3,4,5-tetraphenyl-2,3-dihydro-1H-imidazole, and 1-(1-adamantyl)-5-cyanomethyl-3,4-diphenyl-4,5-dihydro-1H-1,2,4-triazole are characterized by partial conjugation in the heteroring; some compounds exhibit luminescence under UV irradiation. 1,3-Bis(1-adamantyl)benzimidazol-2-ylidene reacted with molecular sulfur in benzene to give 1,3-bis-(1-adamantyl)-2,3-dihydro-1H-benzimidazole-2-thione, but it failed to react with selenium under analogous conditions.