Synthesis of 5-Substituted 1,3-Dimethylpyrazolo[4,3-e][1,2,4]triazines

A novel method for the synthesis of a new series of 5-substituted 1,3-dimethyl pyrazolo[4,3-e][1,2,4]triazines is described. The new synthetic strategy is based on the classical Bischler 1,2,4-benzotriazine synthesis. This approach involves the preparation of 5-hydrazinopyrazole from 5-chloro-1,3-dimethyl-4-nitropyrazole followed by acylation and nitro group reduction to form the corresponding 4-amino-3-(acylhydrazino)pyrazoles. Intramolecular oxidative cyclization of the latter derivatives, using polyphosphoric acid, produced the respective target pyrazolotriazines.     

Pyrano[4,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidinium salts

5-Aroyl-1,3,6-trimethyluracils were converted to pyrano[4,3-d]pyrimidinium salts. Reactions of the salts obtained with ammonia, primary amines, and hydrazine were studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2251–2257, November, 2007.     

Synthesis of pyrazolo[4,3-<Emphasis Type="Italic">e</Emphasis>][1,2,4]triazolo[4,3-<Emphasis Type="Italic">c</Emphasis>]pyrimidines

Starting from 1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-ones, a synthesis pathway to the tricyclic pyrazolo[4,3-e][1,2,4]triazolo[4,3-c]pyrimidines is described. Reaction of 1,5-dihydro-4H-pyrazolo[3,4-d] pyrimidin-4-ones with phosphoryl chloride afforded the corresponding 4-chloro-1H-pyrazolo[3,4-d]pyrimidines. Treatment of these compounds with hydrazine hydrate at reflux temperature gave the hydrazino derivatives, which were subsequently cyclized to the titled compounds on heating with orthoesters in ethanol. Correspondence: Abolghasem Davoodnia, Department of Chemistry, School of Sciences, Islamic Azad University, Mashhad Branch, Mashhad 91735-413, Iran.     

2-Substituted [1]benzopyrano[4,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-5-ones

A new method is reported for the synthesis of 2-R-substituted [1]benzopyrano[4,3-d]pyrimidin-5-ones (R = p-phenyl, p-chlorophenyl-, p-carbamoylphenyl-, 3-pyridinyl-, 4-pyridinyl-, 2-pyrazinyl-, pyrrolidino-,morpholino-, 3,6-dimethyl-1-pyrazolyl-) by the reaction of 4-chloro-3-formylcoumarin with salts of the corresponding amidines RC(=NH)NH₂HX in DMF in the presence of piperidine or triethylamine. 3-Formyl-4-coumarin and 2-aminobenzimidazole give __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 935–940, June, 2007.     

Synthesis and reductive reactions of 2,3-dioxo-2,3-dihydrobenzo[<Emphasis Type="Italic">b</Emphasis>]furo[2,3-<Emphasis Type="Italic">f</Emphasis>]-, -[2,3-<Emphasis Type="Italic">g</Emphasis>]-, and -[3,2-<Emphasis Type="Italic">e</Emphasis>]indoles

The Sandmeyer reaction was used to prepare 2,3-dioxo-2,3-dihydrobenzo[b]furoindoles which could be reduced with diborane or with complex hydrides to give the corresponding unsubstituted as well as the 3-hydroxybenzo[b]furoindoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 11, pp. 1683–1689, November, 2004.     

Synthesis of 6-aryl-1,6-dihydrodipyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>:4,3-<Emphasis Type="Italic">c</Emphasis>]pyridines

6-Azido-1H-pyrazolo[3,4-b]pyridino-5-carbaldehydes react with aromatic amines to give the corresponding N-arylimines which cyclize on heating in boiling toluene to give 6-aryl-1,6-dihydrodipyrazolo[3,4-b:4,3-e]pyridines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1717–1722, November, 2004.     

Alternative Routes to the Pyrazolo[4,3-<Emphasis Type="Italic">e</Emphasis>][1,2,4]triazolo-[1,5-<Emphasis Type="Italic">c</Emphasis>]pyrimidine System

Formimidic acid esters derived from 1-substituted 5-aminopyrazole-4-carbonitriles reacted with carboxylic acid hydrazides on heating to give 2,7-disubstituted pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives as a result of double heterocyclization. The same compounds were obtained by thermal recyclization of 1-aroyl-2-(1-R-pyrazolo[3,4-d]pyrimidin-4-yl)hydrazines.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 934–938.Original Russian Text Copyright © 2005 by Tyurin, Vorob’ev, Minyaeva, Krasnikov, Mezheritskii.     

Synthesis of 2,3-<Emphasis Type="Italic">cis</Emphasis> Stereomeric Emetamines <Emphasis Type="Italic">via Reissert</Emphasis> Compounds

Summary. Alkylation of Reissert compounds with certain benzoquinolizinone derivatives followed by hydrolytic cleavage afforded the core of the title compounds in a two step sequence. Finally, the lactam intermediates were reduced with DIBAH giving the target compounds, the structural and stereochemical assignments of which were achieved by ¹³C NMR spectroscopy. Part of PhD thesis, LMU München, D     

5-Arylidene Derivatives of <Emphasis Type="Italic">Meldrum</Emphasis>’s Acid as Synthons in Pyrano[4,3-<Emphasis Type="Italic">b</Emphasis>]pyran Synthesis

Summary. The reactions of 5-arylidene derivatives of Meldrum’s acid with ethyl vinyl ether or N-vinyl-2-oxazolidinone yielded trans-trans-(2,4:4,7)-pyrano[4,3-b]pyrans, cis-trans-(2,4:4,7)-pyrano[4,3-b]pyrans, or diastereoisomeric mixtures of pyrano[4,3-b]pyrans and reactions with 3,4-dihydro-2H-pyran afforded Michael adducts. The reactions of 5-arylidene derivatives of Meldrum’s acid with cyanoacetic acid derivatives do not provide appropriate pyrans.     

Synthesis and properties of pyrimido[4,5-<Emphasis Type="Italic">a</Emphasis>]- and pyrido[4,3-<Emphasis Type="Italic">a</Emphasis>]carbazole derivatives

Methods for the synthesis of substituted pyrimido [4,5-a]- and pyrido[4,3-a]carbazoles were proposed. Condensation of 2-(dimethylaminomethylene)-6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-one with guanidine and thiourea afforded 2-amino-8-methyl-6,11-dihydro-5H-pyrimido[4,5-a]carbazole and 8-methyl-3,5,6,11-tetrahydro-2H-pyrimido[4,5-a]carbazole-2-thione, respectively. The reaction of cyano(6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-ylidene)acetamide with dimethylformamide dimethyl acetal gave N-(dimethylamino-methylene)cyano(6-methyl-2,3,4,9-tetrahydro-1H-carbazol-1-ylidene)acetamide. Cyclization of the latter yielded 1-cyano-8-methyl-3,5,6,11-tetrahydro-2H-pyrido[4,3-a]carbazol-2-one.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2740–2744, December, 2004.     

Pyridyl-substituted [1,3]Dithiolo-[4,5-<Emphasis Type="Italic">b</Emphasis>][1,4]dithiine-2-thiones

We have obtained 5-(2-pyridyl)[1,3]dithiolo[4,5-b][1,4]dithiine-2-thione for the first time by cycloaddition of 2-ethynylpyridine to 4,5-dihydro-1,3-dithioltrithione (isotrithionedithiol). We have studied this thione, 5-(2-pyridyl)- and 5-(4-pyridyl)-5,6-dihydro[1,3]dithiolo[4,5-b][1,4]dithiine-2-thiones by mass spectroscopy and also IR, UV, ¹H and ¹³C NMR spectra. We have determined the crystal and molecular structure of 5-(2-pyridyl)-5,6-dihydro[1,3]dithiolo[4,5-b][1,4]dithiine-2-thione.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 429–434, March, 2005.     

Synthesis of Condensed and Uncondensed Tetrazolo[1,5-<Emphasis Type="Italic">b</Emphasis>][1,2,4]triazines as Potential Antimicrobial Agents

Summary. Reactions of two cyclic amidrazones, the 6-methyl and 6-phenyl derivatives of 7-hydrazinotetrazolo[1,5-b][1,2,4]triazines with mono- and dicarbonyl compounds afforded various heterocyclic systems. Thus, acetic acid, benzoyl chloride, or ethyl chloroformate reacted with the former cyclic amidrazones to yield the corresponding [1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]triazines. With pyruvic acid or ethyl pyruvate the corresponding hydrazone derivatives were obtained, which then cyclized to tetrazolo[1′,5′:2,3][1,2,4]triazino[5,4-c][1,2,4]triazines. The 9,10-dioxotetrazolo-triazinotriazine structures were synthesized by condensative cyclization of the cyclic amidrazones with diethyl oxalate, whereas the reaction of these amidrazones with acetylacetone or ethyl acetoacetate furnished pyrazolyltetrazolo[1,5-b][1,2,4]triazines through the isolable hydrazone intermediates. Some of the representative members of the prepared compounds were screened for antimicrobial activity.     

Ionic Liquid Promoted One-Pot Synthesis of Furo[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine-2,4(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>)-diones

Summary. The three-component condensation of aldehyde, N,N′-dimethylbarbituric acid and alkyl or aryl isocyanide afforded the corresponding furo[2,3-d]pyrimidine-2,4(1H,3H)-diones in 1-butyl-3-methylimidazolium bromide as an ionic liquid in high yields at room temperature within several minutes.     

Synthesis of Some New Fused and Polyfused [1,2,4]Triazolo-[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazepines

7-[1,3-Dithiolan-2-ylidene]-3-phenyl-5,6,7,8-tetrahydro[1,2,4]triazolo[3,4-b][1,3,4]thiadiazepine-6,8-dione and 7-[5-oxo-1,3-dithiolan-2-ylidene]-3-phenyl-5,6,7,8-tetrahydro[1,2,4]triazolo[3,4-b][1,3,4]-thiadiazepine-6,8-diones were obtained by treating 3-phenyl-5,6,7,8-tetrahydro[1,2,4]triazolo-[3,4-b][1,3,4]thiadiazepine-6,8-diones with CS₂ and chloroacetyl chloride, respectively. Treatment of the above compounds with mercaptoacetic acid gave 1,2-dibromoethane or the corresponding spiro polyfused heterocycles. Some other triazolothiadiazepine derivatives including spiro polyfused compounds were also synthesized. __________ Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 8, 1256–1264, August, 2005.     

Efficient <Emphasis Type="Italic">Baylis-Hillman</Emphasis> Reaction <Emphasis Type="Italic">via</Emphasis> a 1,4-Diazabicyclo[2.2.2]octane-based Ionic Catalyst

Summary. A novel ionic catalyst, 1-butyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride based on 1,4-diazabicyclo[2.2.2]octane was synthesized and applied in the Baylis-Hillman reaction, which occurred readily at room temperature to afford the corresponding adducts in good yield. The ionic catalyst could be recycled for seven runs without diminution in its catalytic activity.