Representatives Of New Heterocyclic System Research Articles

Cyclopropanation of areno-condensed 4H-pyrans with dihalocarbenes

The addition of dihalocarbenes to 1H-benzo[f]chromenes and 4H-chromenes gave a number of dihalotetrahydro(benzo)cyclopropa[b]-chromenes containing donor and acceptor substituents at different positions. It was found that in the case of 1,3-disubstituted 1H-benzo[f]-chromenes, the reaction proceeds diastereoselectively with the formation of trans-isomers. 12H,13H-7a,12a-Methanobenzo[f]indeno-[1,2-b]chromene and 12,13-dihydro-14H-7a,13a-methanodibenzo[a,h]xanthene, representatives of new heterocyclic systems, were obtained.

Synthesis of 2-Aryl-5-oxo-5H-thiopyrano[4,3-b]pyridine-7-carboxylic Acids as the First Representatives of a New Heterocyclic System

A series of ethyl 2-[(Z)-(4-oxo-2-thioxo-1,3-thiazolidin-5-ylidene)methyl]-6-arylnicotinoates was obtained as a result of the reaction of 6-aryl-2-formylnicotinoates with rhodanine. Under alkaline conditions, they underwent recyclization to form 2-aryl-5-oxo-5H-thiopyrano[4,3-b]pyridine-7-carboxylic acids—the first representatives of new heterocyclic system.

Synthesis of 2H-Thiopirano[3,4-c]pyrazol-7-one Derivatives as the First Example a New Heterocyclic System

A series of ethyl 4-[(Z)-(4-oxo-2-thioxo-1,3-thiazolidin-5-ylidene)methyl]-1-aryl-1H-pyrazole-3-carboxylates was obtained as a result of the reaction of ethyl 4-formyl-1-aryl-1H-pyrazole-3-carboxylates with rhodanine. Under the action of NaOH, the prepared pyrazole-3-carboxylates underwent recyclization to form 2-aryl-7-oxo-2,7-dihydrothiopyrano[3,4-c]pyrazole-5-carboxylic acids—the first representatives of new heterocyclic system.

2-Dicyanomethylidene-3-ethoxymethylidene-2,3-dihydroindole in the synthesis of fused tri- and tetracyclic systems

The reactions of 2-dicyanomethylidene-3-ethoxymethylidene-2,3-dihydroindole with hydrazine hydrate and phenylhydrazine afforded 2,3-diamino-4-cyanopyrido[4,3-b]indole and 3-amino-2-anilino-4-cyanopyrido[4,3-b]indole, respectively, and the reactions of the latter compounds with dimethylformamide diethyl acetal were studied. The reactions of 2,3-diamino-4-cyanopyrido[4,3-b]indole with benzaldehyde, ethyl acetoacetate, and acetylacetone were investigated. First representatives of new heterocyclic systems, viz., [1,2,4]triazolo[1’,5’:1,6]-pyrido[4,3-b]indole and pyrazolo[1’,5’:1,2]pyrido[4,3-b]indole, were synthesized. The structure of ethyl 6-cyano-5-[(E)-(dimethylamino)methylideneamino]-2-methyl-7H-pyrazolo-[1’,5’:1,2]pyrido[4,3-b]indole-1-carboxylate was established by X-ray diffraction.

Synthesis and molecular structure of bis(benzo)aza-14-crown-4 ethers with 7-azabicyclo[3.3.1]nonane and homologous fragments

By condensation of cycloalkanes with 2-{2-[2-(2-formylphenoxy)ethoxy]ethoxy}benzaldehyde and ammonium acetate by Petrenko-Kritchenko method first representatives of new heterocyclic systems, bis(benzo)-aza-14-crown-4 ethers containing a 7-aza-bicyclo[3.3.1]nonane or its homologous fragment, were obtained in 6–15% yield. With growing cycle of the initial cycloketone the yield of the azacrownophane considerably grew. By means of XRD analysis the molecular structure was established of four synthesized macrocycles, the relative configuration of asymmetrical atoms was determined, and the size of the internal cavities of the azacrown part was estimated.

Study of nitrogen- and sulfur-containing heterocycles. 46. New heterocyclic systems ? Derivatives of pyrido[3?,2??5,6][1,4]thiazino[3,4-c]- and pyrimido-[5?,4??5,6][1,4]thiazino[3,4-c][1,2,4]triazines. Synthesis, properties

Representatives of new heterocyclic systems were obtained — pyrido[3′,2′∶5,6][1,4]thiazino[3,4-c]- and pyrimido[5′,4′∶5,6][1,4]thiazino[3,4-c][1,2, 4]triazines. Hydrazides of N-(pyrid-3-yl)- and N-(pyrimid-5-yl)oxamic acids were isolated and characterized. Their acylation products were investigated.

Synthesis of derivatives of pyrazino[1,2-a]benzimidazole, aza analogs ofβ-carboline

1. A new method of synthesis of derivatives of imidazo[1,2-a]pyrazine and pyrazino[1,2-a]benzimidazole, representatives of new heterocyclic systems, was proposed. 2. It was shown that dehydrogenation over Raney nickel under mild conditions is a convenient method of synthesis of benzimidazoles from benzylimidazolines and of benzimidazo[1,2-a]quinoxaline derivatives from the corresponding tetrahydro derivatives. 3. A method of synthesis was developed for 2-benzoylbenzimidazoles by oxidation of the widely accessible 2-benzylbenzimldazoles.