Heterocyclic derivatives of purines. 4. Reactions of thiazolo[3,2-f]xanthineS

The chemical transformations of 2- and 3-substituted thiazolo[3,2-f]xanthines with electrophilic reagents were studied, and it was established that the 2 position of the thiazole ring is active in bromination, while the para position of the aryl substituent is active in nitration. The structures of the substances obtained were established from the IR, PMR, and mass-spectral data.See [1] for Communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1267–1271, September, 1981.     

A facile synthesis of 2,3-dihydroimidazo- and 1,2,3,4-tetrahydropyrirnido[1,2-f] phenanthridines

When 6-(2-hydroxyethyl)amino -(1 ), 6-(3-hydroxypropyl)amino -(2 ),or 6-[2-(1-hydroxybutyl)]-aminophenanthridines ( 3 ), dissolved in concentrated sulfuric acid, were treated with nitrosylsulfuric acid at 0–25, then diluted with water and basified with aqueous sodium hydroxide at 65–86°, 2,3-dihydroimidazo- ( 4a-i ), 1,2,3,4-tetrahydropyrimido- ( 5 ), or 2,3-dihydro-2-ethyl-imidazo[1,2-f]phenanthridines ( 4j-p ) were obtained respectively in good yields. Structures were substantiated by ir spectroscopy. The 6-ω-hydroxyalkylaminophenanthridines were prepared from the corresponding 6-chlorophenanthridines. A possible mechanism for the formation of these ring systems is postulated.     

A new method for the synthesis of novel 1,2,4-triazolo[3,4-f][1,2,4]triazines

Novel compounds 8-(quinoxalin-2-yl)-1,2,4-triazolo[3,4-f][1,2,4]triazines 3a,b were obtained by a new annulation method in the 1,2,4-triazine synthesis.     

Novel one-step synthesis of thiazolo[3,2-b]1,2,4-triazoles

[reaction: see text] Reactions of chalcones 3a-f with bis(1H-1,2,4-triazolyl) sulfoxide 4 formed the thiazolo[3,2-b]1,2,4-triazoles 5a-f, which resemble closely some previously prepared COX-2 inhibitors. The structure of 5a was confirmed by X-ray analysis.     

A facile synthesis of cis-1-methyl-1,2,3,3a,4,8b- hexahydropyrrolo[3,2-f]pyrindine,an annulated nicotine analog

[reaction: see text] The title compound, 2, has been synthesized in 45% overall yield in six steps from 3-bromopyridine. The hexahydropyrrolo[3,2-f]pyrindine skeleton was constructed from key intermediate 5, via intramolecular azomethine ylide-alkene [3 + 2] cycloaddition. The present work constitutes a general method for rapid assembly of other related tricyclic nicotine analogues.     

1,2,4-Triazines. Synthesis of selected members of the s-triazolo[3,4-f]- [1,2,4] triazine and tetrazolo[1,5-f] [1,2,4] triazine ring systems

A convenient synthesis of 3-amino-6-hydrazino-5(2H)[1,2,4]triazinone 4 has been developed and a study of the reactions of 4 with aliphatic acids, orthoesters and miscellaneous active carbonyl reagents has been undertaken. When 4 was refluxed in either neat acid or orthoester in dimethylformamide, a facile ring closure reaction with the N-1 nitrogen of the 1,2,4-triazine ring occurs affording a novel series of 3-aIkyl(aryl)-8(5H)-s-triazolo[3,4-f] [1,2,4]triazinones ( 6–11 ). Ring closure with carbon disulfide and cyanogen bromide is also reported affording 6-amino-3(2H)thio-8(5H)-s-triazolo[3,4-f] [1,2,4]triazinone 12 and 3,6-diamino-8(5H)-s-triazolo-[3,4-f] [1,2,4]triazinone 14 , respectively. In addition 4 has been converted into 3-amino-6-azido-5(2H)-1,2,4-triazinone 15 which was employed in a study of azide-tetrazole equilibrium affording 6-amino-8(5H)tetrazolo[1,5-f][1,2,4]triazinone 16 . Rates for interconversion at various temperatures were measured and an activation energy for the process determined.     

Polymethine dyes — Furo[3,2-f]quinol-7-yl and furo[3,2-f]quinol-9-yl derivatives

New heterocyclic bases — 7- and 9-methylfuro[3,2-f]quinolines — were synthesized by condensation of 5-aminobenzofuran double tin hydrochloride salt with paraldehyde in dilute hydrochloric acid and with methyl vinyl ketone in ethanol in the presence of ferric chloride and zinc chloride. Polymethine dyes of various types were obtained from the quaternary salts of the synthesized bases. The introduction of a furan ring in the 5,6 position of quino-2- and quino-4-carbocyanines gives rise to a smaller bathochromic effect than the analogous introduction of a thieno and, particularly, a benzo group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 391–394, March, 1977.     

A facile, aqueous phase green synthetic protocol for the synthesis of 5,9b-dihydro-1H-[1,2,4]triazino[5,6-b]indole-3-ols/5,9b-dihydro-1H-[1,2,4]triazino[5,6-b]indole-3-thiols

5,9b-Dihydro-1H-[1,2,4]triazino[5,6-b]indole-3-ols/5,9b-dihydro-1H-[1,2,4]triazino[5,6-b]indole-3-thiols were synthesized for the first time in water under neutral conditions by using isatin, semicarbazide/thiosemicarbazide, mediated by β-cyclodextrin in excellent yields. β-Cyclodextrin has been recovered and reused without any loss of catalytic activity.     

Research on pyrrolo[3,2-f]indolizines

3-(-Oxo--alkoxycarbonylalkyl)- and 3-benzoyl-substituted pyrroles undergo condensation with -unsubstituted pyrroles to give 6H-pyrrolo[3,2-f]indolizines that contain higher acid residues or a phenyl group in the 4 position of the heteroring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 777–780, June, 1977.See [1] for communication IV.     

First synthesis of 4H-furo[3,2-f]pyrrolo[1,2-a][1,4]diazepines

The synthetic pathway leading to 4-H-furo[3,2-f]pyrrolo[1,2-a][1,4]diazepines is described in five steps starting from 2-hydroxyketones via 2-amino-3-furonitriles.     

Synthesis of substituted pyrrolo[3,2-f]quinolines

Reactions of 2,3,6-trimethyl- and 2,6-dimethyl-6-methoxy-5-aminoindoles with 1,3-dicarbonyl compounds represent a convenient route for obtaining substituted pyrrolo[3,2-f]quinolines, even though the presence of a methoxy group on the benzene ring sometimes lowers the reactivity of the amine, thus increasing the required reaction time and reducing the yield.M. E. Evsev'ev Mordovian State Pedagogical Institute, Saransk 430007. M. V. Lomonosov Moscow State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1080–1087, August, 1997.     

Synthesis and properties of oxazolo[3,2-f]xanthines

Oxazolo[3,2-f]xanthines were synthesized by the reaction of 7-acylalkyl-8-bromo-3-methyl- and -1,3-dimethylxanthines with sodium benzoate in dimethylformamide. Their alkylation with methyl iodine was studied. The reaction of oxazolo[3,2-f]xanthines with primary amines leads to the previously described imidazo[1,2-f]xanthines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 534–537, April, 1988.     

New synthesis of 5,6-dihydrothiazolo[3,2-b][1,2,4]triazoles

Russian Journal of Organic Chemistry -     

A facile synthesis of the novel thiazolo[3,2-a]pyrimidine derivatives

2-Bromomethyl- and 2-iodomethyl-2,3-dihydrothiazolo[3,2-a]pyrimidin-5-ones are prepared via the reaction of 3-allyl-2-thiouracil derivatives with bromine or iodine chloride, respectively. The 6-bromo and 6-nitro derivatives are synthesized by an electrophilic substitution at C-6 of the thiazolopyrimidine system. As a result, novel 2,3-dihydrothiazolo[3,2-a]pyrimidin-5-one derivatives are obtained. Hydrogen halide elimination from the 2-halomethyl-2,3-dihydrothiazolo[3,2-a]pyrimidin-5-ones is also reported.