Synthesis of pyrido[3,4-b]pyrano[3,4-b]indoles

The synthesis of some pyrido[3,4-b]pyrano[3,4-b]indoles ( 3 ) from 3-hydroxy-4-(3-indolyl)piperidines ( 6 ) is reported.     

Synthesis of 9-chloropyrazolo[4,3-b]quinolines

A series of 1-methyl-4-arylaminopyrazole-3- and -5-carboxylic acids were synthesized by the reaction of 1-methyl-4-halopyrazole-3- and -5-carboxylic acids with aromatic amines in the presence of a copper catalyst; treatment with phosphorus oxychloride converted them to the corresponding 9-chlorosubstituted 1-methyl-1H- and 2-methyl-2H-pyrazolo[4,3-b]quinolines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1123–1125, August, 1984.     

Synthesis of pyrazolo[3,4-b][1,4]diazepines and pyrazolo[3,4-b]pyrazines

The synthesis and structure elucidation of new pyrazolo[3,4-b][1,4]diazepines and pyrazolo[3,4-b]pyrazines are reported and the characterisation of isomers and tautomers by proton and carbon-13 nmr are discussed. In some case only NOE experiments allow us to identify the isomeric structure.     

Synthesis of pyrrolo[2,3-b]azepine-4,7-dione derivatives

The Dieckmann reaction has been successfully applied for the first time in the synthesis of pvrrolo[2,3-b)]azepines.     

Synthesis of quinolono[4,3-b] and [3,4-b]carbazoles potential DNA binders

2-and 3-β-[arylvinyl]indoles, obtained by Wittig-Horner reaction of the corresponding N-benzenesulfonylbromomethylindoles with o-nitrobenzaldehydes, gave 2- and 3-arylcarbazoles respectively upon Diels-Alder reaction with DMAD. On reductive cyclisation, these carbazoles gave the title compounds.     

Benzo[f]isoindole analogs II. Thieno[3,4-b]quinoxaline

The transient existence of thieno[3,4-b]quinoxaline ( 2d ) as a product of dehydration of 1,3-dihydrothieno[3,4-b]quinoxaline 2-oxide ( 5 ) was demonstrated by trapping experiments with N-phenylmaleimide and dimethyl acetylenedicarboxylate. Attempts to isolate 2d from reaction mixtures arising from dehydration of 5 and from dehydrogenation of 1,3-dihydro-thieno[3,4-b]quinoxaline ( 8 ) were unsuccessful.     

A Novel Synthesis of 3,4-Discubstituted-1H-pyrazolo[3,4-b]quinolines

A simple and efficient synthesis of pyrazolo[3,4-b] quinolines is described. The synthesis involves reaction of 2-amino-3-cyanoquinoline-4-carboxylates(1) with hydrazine hydrate to give regioselectively only pyrazolo[3,4-b]quinolines (2). No formation of pyridazino quinolines (3) is observed.     

Synthesis of thieno[2,3-d]thia[1]pyrano[4,3-b]pyrrole derivatives

It is shown that 2-methyl-3-carbethoxy-4H,8H,5,6-dihydrothieno[2,3-d]thia[1]pyrano [4,3-b]pyrrole and 8-methyl-9-carbethoxy-10H,5,6-dihydrothieno[2,3-d]thia[1]chromeno[4,3-b]pyrrole and their S,S-dioxides, respectively, are obtained in the reaction of 2-methyl-3-carbethoxy-4-thienylhydrazine with tetrahydro-4-thiopyrone, tetrahydro-4-thiopyrone S, S-dioxide, 4-thiochromanone, and 4-thiochromanone S,S-dioxide in the presence of an acid catalyst.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 195–196, February, 1979.     

Synthesis of pyrano[3,4-c]pyrazole and pyrazolo[3,4-d][1,2]diazepine derivatives

By the action of thionyl chloride on 3(5)-R-4-phenacylpyrazole-5(3)-carboxylic acid ( 3c,d ), 3-R-5-phenylpyrano[3,4-c]pyrazole-7-(1H)ones ( 4c,d ) were obtained. When 4c,d were treated with hydrazine hydrate followed by refluxing in ethanol containing acetic acid, 4,7-dihydro-3-R-5-phenylpyrazolo[3,4-d][1,2]-diazepin-8-(1H)ones ( 6c,d ) were formed. Compounds 6c,d , in turn, were refluxed in ethanol saturated with hydrochloric acid to yield 6-amino-1,6-dihydro-3-R-5-phenyl-7H-pyrazolo[3,4-c]pyridin-7-ones ( 7c,d ). Compounds 7c,d could be obtained directly from 5c,d. The starting materials 3c,d were prepared by hydrolysis of the oxime of 3(5)-R-4-phenacyl-5(3)carboalcoxypyrazoles ( 1a,b ). Structural assignments rested on correct elemental analysis, molecular weights determined by mass spectrometry, and spectroscopic evidence.     

Synthesis of 1,2,3,4,6,7,8,9-octahydropyrimido[4,5-b]quinoline-2,4-dione

In the presence of hydrazine hydrate or sodium ethylate, ethyl 2-[(N-phenylcarbamoyl)amino]-5,6,7,8-tetrahydroquinoline-3-carboxylate is converted to 3-amino- or 3-phenyl-1,2,3,4,6,7,8,9-octahydropyrimido[4,5-b]quinoline-2,4-dione. Compounds analogous to the latter are also obtained during heating of 2-amino-5,6,7,8-tetrahydroquinoline-3-carboxylic arylamides with phenyl isocyanate or from their N-phenylcarbamoyl derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1114–1117, August, 1989.     

Synthesis of hexahydroazonino[5,6-b]indoles from hexahydroazepino[4,3-b]-and-[3,4-b]indoles and activated alkynes

A reaction of substituted hexahydroazepino[4,3-b]-and-[3,4-b]indoles with activated alkynes was studied. A one-step method for the synthesis of isomeric hexahydroazonino[5,6-b]indoles different by positions of the double bond in the azonine ring was developed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2244–2250, November, 2007.     

Synthesis of 10-deazariboflavin and related 2,4-Dioxopyrimido[4,5-b]quinolines

Condensation of substituted anthranilaldehydes with barbituric acid results in the formation of 2,4-dioxopyrimido[4,5-b]quinolines. Using this general synthetic approach, 7,8-dimethyl-2,4-dioxo-10-ribityl-2,3,4,10-tetrahydropyrimido[4,5-b]quinoline (10-deazariboflavin) was prepared by the condensation of barbituric acid with 4,5-dimethyl-N-ribitylanthranilaldehyde. The latter was obtained in situ by the treatment of 1-[4,5-dimethyl-N-(ribityl)anthraniloyl]-2-(p-toluenesulfonyl)hydrazine, prepared from 4,5-dimethylanthranilic acid with anhydrous sodium carbonate.     

Efficient synthesis of chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives via multicomponent one-pot reaction under mild reaction conditions in water

10-Methyl-7-aryl-7,12-dihydro-6H,8H-chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives are significant class of compounds and this is critical to develop methods in water using commercially available and non-toxic catalysts. In this paper, an efficient method is introduced for the synthesis of 10-methyl-7-aryl-7,12-dihydro-6H,8H-chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives. For the synthesis of the desired products, a multicomponent reaction was designed and performed between 4-hydroxycoumarin, an aldehyde, 6-methyl-2H-pyran-2,4(3H)-dione, and ammonium acetate. The products are obtained under green conditions in water in the presence of a catalytic amount of L-proline (10 mol%). The advantage of this method is no need to any toxic solvent, which is critical from the environmental viewpoint. A possible mechanism was suggested, which confirms the role of L-proline in the reaction as the catalyst.

     

A ‘One Pot’ Synthesis of Acenaphtho[1,2-b]Benzo[f] and Acenaphtho[1,2-b]Benzo[h]Quinolines

A short, simple and high yielding ‘one pot’ synthesis of two acenaptho[1,2-b]benzo-quinolines have been described which involved highly regioselective thermal cyclization of enaminoimine hydrochlorides from 2-chloro-1-formylacenaphthylene and ½-naphthylamine.     

Dimroth rearrangement in the row of new pyrano[3,4-c][1,2,4]triazolo[4,3-a][1,5-a]pyridines and synthesis of new heterocyclic systems: Pyranopyrazolo[4,3-e][1,2,4]triazolopyridines

New and effective methods for the synthesis of derivatives of pyrano[3,4-c][1,2,4]triazolo[4,3-a][1,5-a]pyridines were developed. Synthesized new tetracyclic heterocyclic systems containing pyrano[3,4-c]pyridine ring unknown in the literature were obtained for the first time. The rearrangement of Dimroth in the triazolo[4,3-a]pyridine systems for the first time was studied. The possibility of rearrangement of Dimroth in the new heterocyclic system has been investigated.     

A novel pentacyclic pyridine dilactone. 7-methyl[1]benzopyrano[4,3-d][1]benzoxacino[4,3-b]pyridine-6,16-dione

When equimolar quantities of salicylaldehyde 2 and ethyl 3-amino-2-butenoate 3 or its constituents (ethyl 3-oxobutanoate and ammonia) were refluxed on a steam-bath for 6 hours with a trace of acetic acid, two products, a pentacyclic pyridine dilactone 4 and 3-acetyl coumarin 5 , resulted in 15% and 45% yields, respectively. The structure of 4 was elucidated as 7-methyl[1]benzopyrano[4,3-d][1]benzoxacino[4,3-b]-pyridine-6,16-dione on the basis of its spectral data. The mechanism of its formation has been discussed. The reaction has been extended to three more substituted salicylaldehydes.     

Efficient Synthesis of Fluorinated [1,2,4]Triazolo[3,4-b][1,3,4]thiadiazoles

Russian Journal of Organic Chemistry - An efficient synthesis of fluorinated [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives has been achieved by cyclocondensation of 5-substituted...     

Synthesis of 4-substituted pyrano[4,3-b]pyran-2,5-diones in an ionic liquid

The mildly basic ionic liquid N,N,N,N-tetramethylguanidinium triflate (TMGTf) was found to be a very effective solvent for the reaction between 4-hydroxy-6-methyl-2H-pyran-2-one, Meldrum's acid, and aldehydes to afford some novel pyrano[4,3-b]pyran-2,5-diones in high yields at room temperature. The stages, through which these reactions might proceed, depend largely on the nature of the aldehyde substrates. The reaction of aliphatic aldehydes has given access to some novel carboxylated products.     

Synthesis of pyrano[3,4-c]thieno[3,2-e][1,2,4]triazolo[4,3-a]pyridines,representatives of a new fused heterocyclic system

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