Synthesis of 2-aryl-3-hydroxypyrazolo-[4, 3-b]quinuclidines

The reaction of 2-ethoxycarbonyl-3-ketoquinuclidine with arylhydrazines has been examined It is shown that the first stage in the reaction is the formation of 2-ethoxycarbonyl-3-(-arylhydrazino)-²-dehydroquinuclidines, which are then converted into 2-aryl-3-hydroxy-pyrazolo[4, 3-b]quinuclidines (III). The O-methyl- and O-benzoyl- derivatives of III have been synthesized.Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1261–1263, September, 1970.     

7-Aryl-4a-hydroxy-4a,6,7,7a-tetrahydroisoxazolo[4,5-b]quinuclidines as NO Donors

7-Aryl-4a-hydroxy-4a,6,7,7a-tetrahydroisoxazolo[4,5-b]quinuclidines have been prepared from 2-arylmethylene-3-quinuclidones and hydroxylamine and they are able to release NO upon mild oxidation with K₃[Fe(CN₆)] in basic medium.     

Synthesis and properties of 1,2-dihydropyridazino[4,5-b]indole

The intramolecular cyclization of 2-indoylhydrazones of aromatic aldehydes leads to 1-aryl-1,2-dihydropyridazino [4,5-b]indol-4-ones. The chemical properties of the compounds obtained were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1654–1658, December, 1973.     

Synthesis of imidazo[4,5-b]- and [4,5-c]pyridines

2-Arylimidazo[4,5-b]- and [4,5-c]pyridines have been prepared by treatment of the appropriate 2,3- or 3,4-diaminopyridine with an aromatic carboxylic acid in the presence of polyphosphoric acid. Other derivatives have been prepared by similar cyclisation of diaminopyridines using triethyl orthoformate, urea, thiophosgene and thiourea and the properties of some N-oxides have been investigated. A number of the arylimidazopyridines have been screened for mutagenicity.     

Quaternization of 1H-imidazo[4,5-b]pyridine and 4-methyl-4H-imidazo[4,5-b]pyridine

Unsubstituted imidazo[4,5-b]pyridine adds methyl iodide to the pyridine N atom. Treatment of the resulting iodide with base forms 4-methyl-4H-imidazo[4,5-b]pyridine. This nucleophile can readily add methyl iodide to form only one salt, 1,4-dimethylimidazo[4,5-b]pyridinium iodide.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Chemistry, Ukraine Academy of Sciences, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1232–1233, September, 1994. Original article submitted june 17, 1994.     

Synthesis and properties of 1,2-dihydropyridazino[4,5-b]indole II

The possibility of the synthesis of substituted 1,2-dihydropyridazino[4,5-b]indoles by the reaction of 1-methyl-2-carbomethoxy-3-(α-halobenzyl)indole or 1-methyl-2-carbomethoxy-3-(α-acetoxybenzyl)indole with hydrazines was demonstrated. The oxidation, reduction, and acylation reactions of the resulting 1,2-dihydropyridazino[4,5-b]indoles were studied.     

Synthesis, properties, and structures of benzo[1,2-b:4,5-b']bis[b]benzothiophene and benzo[1,2-b:4,5-b']bis[b]benzoselenophene

Employing two consecutive cyclization reactions, benzo[1,2-b:4,5-b']bis[b]benzochalcogenophenes, which are pi-extended heteroarenes, were efficiently synthesized. Their electronic and crystal structures were elucidated on the basis of UV-vis spectra, electrochemical measurements, and X-ray structural analyses.     

Synthesis of tricyclic 4-chloro-pyrimido[4,5-b][1,4]benzodiazepines

[reaction: see text] A novel methodology was developed for the efficient synthesis of 4-chloro-pyrimido[4,5-b][1,4]benzodiazepines. The key is the intramolecular Friedel-Crafts cyclization of 5-amino-4-(N-substituted)anilino-6-chloropyrimidine with either a carboxylic acid or its derivatives to construct the 4-chloro-pyrimido[4,5-b][1,4]benzodiazepine core. Subsequent nucleophilic substitution allows the introduction of one more diversity point in the target molecules. This strategy provides an efficient method to access a library of compounds based on privileged substructures that are of great interest in drug discovery.     

Some properties of 1-oxo-4-hydroxypyridazino[4,5-b]quinoxaline

The dissociation constants of 1-oxo-4-hydroxypyridazino[4,5-b]quinoxaline were measured by potentiometric titration. It is shown that this compound is a dibasic acid. Its reaction with organic bases, acids, alkalis, and oxidizing agents was studied. Its aminomethylation, hydroxymethylation, and cyanoethylation were also investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 402–406, March, 1977.     

Synthesis, characterization, self-assembly, and physical properties of 11-methylbenzo[d]pyreno[4,5-b]furan

Synthesis, structure, and physical properties of a novel 11-methylbenzo[d]pyreno[4,5-b]furan (BPF) and its self-assembly in water have been reported. The performance of nanowire-based films in organic light-emitting diodes is much better than that of the thin film deposited by directly drop-coating BPF molecules in THF solution. SEM study indicates that the well-organized structure (nanowires) is an important factor in enhancing the performance of OLED devices.     

N-oxides of imidazo[4,5-b]quinoxalines and imidazo[4,5-b]pyrazines

The N-oxides and N,N-dioxides of methyl derivatives of imidazo[4,5-b]quinoxaline and imidazo[4,5-b]pyrazine were synthesized. The higher reactivity of the 2-methyl group in the N-oxides of 2-methylimidazo[4,5-b]quinoxaline as compared with the corresponding unoxidized derivatives was demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1266–1270, September, 1972.     

Synthesis of pyrimido[4,5-b] indole derivatives

Chemistry of Heterocyclic Compounds -     

The synthesis of 11H-1,2,4-triazolo[4,3-b]pyridazino[4,5-b]indoles,11H-tetrazolo[4,5-b]pyridazino[4,5-b]indoles and 1,2,4-triazolo[3,4-f]-1,2,4-triazino[4,5-a]indoles

This paper describes the synthesis of the previously unknown 11H-1,2,4-triazolo[4,3-b]pyridazino[4,5-b]indoles (2) and 11H-tetrazolo[4,5-b]pyridazino[4,5-b]indoles (3) from 4-hydrazino-5H-pyridazino[4,5-b]indoles (1) , as well as the synthesis of 1,2,4-triazolo[3,4-f]-1,2,4-triazino-[4,5-a]indoles (10) from 2-indolecarbohydrazide (4) . Compounds 2 were obtained by acylation of compounds 1 , followed of thermal cyclization and compounds 3 by treating compounds 1 with nitrous acid. The reactions of compound 4 with formic acid or ethyl orthoformiate gave 1,2-dihydro-1-oxo-1,2,4-triazino[4,5-a]indole (6) . Treating this last compound with phosphorus oxychloride or phosphorus pentasulfide, followed by hydrazine, gave 1-hydrazino-1,2,4-triazino-[4,5-a]indole (9) . Acylation of this last compound, followed of cyclization gave compounds 10 . All the compounds were characterized by elemental analysis and ir and ¹H-nmr spectra.     

Facile synthesis, structure, and properties of benzo[1,2-b:4,5-b']dichalcogenophenes

[reaction, structures: see text] A general and convenient synthesis of benzo[1,2-b:4,5-b']dichalcogenophenes including the thiophene (BDT, 1), selenophene (BDS, 2), and tellurophene (BDTe, 3) homologues is developed. Thus synthesized heterocycles are structurally characterized by single-crystal X-ray analysis, and all three homologues are isostructural with one another. They all have completely planar molecular structures packed in a herringbone arrangement. Their physicochemical properties were also elucidated by means of cyclic voltammetry (CV) and UV-vis spectra.     

Synthesis,structure, and properties of pyrazolo[4,3-b]quinuclidine derivatives

It was shown by means of ¹H and ¹³C NMR spectroscopy that the reaction of 2-arylmethylene-3-oxoquinuclidines with hydrazine hydrate gives 4a-hydroxy-7-aryl-4a,5,7,7a-tetrahydropyrazolo[4,3-b]quinuclidines, which are stable in the crystalline state but undergo dehydration to the corresponding 7-aryl-6H-7,7a-dihydropyrazolo[4,3-b]quinuclidines in solutions. The latter undergo cleavage to 3-(4-piperidyl)-5-arylpyrazoles when they are heated in an alkaline medium.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1248–1256, September, 1985.     

Synthesis and study of the structure of some pyridazino[4,5-b]quinoxaline derivatives

The structures of 1-oxo-4-hydroxypyridazino[4,5-b]quinoxaline and some of its methyl derivatives were established by IR and UV spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 556–561, April, 1973.     

Synthesis of aromatic pyrazolo[4,5-b]pyridine derivatives

Cyclocondensation of chalcones with 5-amino-3-methyl-1-phenylpyrazole leads to the formation of 2,4-diaryl-5-methyl-7-phenyl-3,4-dihydropyrazolo-[4,5-b]pyridines, which undergo aromatization upon treatment with N-bromosuccinimide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1247–1251, September, 1987.     

Synthesis of some pyridazino[4,5-b]quinoxaline derivatives

Several derivatives of the little-studied pyridazino[4,5-b]quinoxaline heterocyclic system, the structural isomer of benzopteridine, were synthesized in order to study their biological activity. 6,7-Dimethylquinoxaline-2,3-dicarboxylic acid and a number of its derivatives were also obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 274–278, February, 1972.