Preparation and characterization of MNPs–PhSO3H as a heterogeneous catalyst for the synthesis of benzo[b]pyran and pyrano[3,2-c]chromenes

Research on Chemical Intermediates - In this study, an efficient and novel procedure has been reported for loading sulfanilic acid on the surface of magnetite Fe3O4 nanoparticles using...     

Condensed pyridopyrimidines. 1. Synthesis of new derivatives of pyrano[3′,4′∶5,6]pyrido[2,3-d]pyrimidines

New derivatives of pyrano[3,45,6]pyrido[2,3-d]pyrimidines were synthesized from ethyl 2-amino-7,7-dimethyl-7,8-dihydro-5H-pyrano[4,3-b]pyridine-3-carboxylate.A. L. Mndzhoyan Institute of Fine Organic Chemistry, National Academy of Sciences of the Republic of Armenia, Erevan. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1239–1241, September, 1999.     

Studies on Thiazolopyridines. Part 1: Antimicrobial Activity of Some Novel Fluorinated Thiazolo[3,2-a]Pyridines and Thiazolo[2′,3′:1,6]Pyrido[2,3-d]Pyrimidines

Ternary condensation of aromatic aldehydes, malononitrile and thioglycolic acid (2:2:1 molar ratio) in ethanol/piperidine afforded the corresponding thiazolo[3,2-a]pyridines 1a-d . Thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 4 was obtained by refluxing of compound 1a with acetic anhydride. Also, thiazolopyrido pyrimidine 6 was produced by refluxing of 1a with triethylorthoformate followed by treatment with hydrazine hydrate. Refluxing 1a with formic acid yielded the thiazolopyridopyrimidine 8 which on chlorination with thionyl chloride furnished the chloro derivative 9 . Finally, amino thiazolo[2',3':1,6]pyrido[2,3-d]pyrimidine 10 was obtained by treatment of 1a with formamide. The structures of these compounds were established on the basis of elemental analyses, IR, 1 H NMR, and mass spectral data. Also, the antimicrobial activity of some synthesized compounds is reported.     

Synthesis of derivatives of pyrido[3′,2′:4,5]furo[3,2-c]isoquinoline heterocyclic system

An approach to the synthesis of derivatives of new heterocyclic system, pyrido[3′,2′:4,5]-furo[3,2-c]isoquinoline, was suggested. A condensation reaction of substituted 3-cyanopyridin-2(1H)-ones with methyl 2-(chloromethyl)benzoate and subsequent treatment of the condensation product with potassium tert-butoxide leads to substituted pyrido[3′,2′:4,5]furo[3,2-c]-isoquinolin-5(6H)-ones. Similarly, a condensation reaction of substituted 3-cyanopyridin-2(1H)-ones with 2-(chloromethyl)benzonitrile and subsequent treatment of the condensation product with potassium tert-butoxide gives substituted 5-aminopyrido[3′,2′:4,5]furo[3,2-c]-isoquinolines.     

Theophylline as a new and green catalyst for the one-pot synthesis of spiro[benzo[α]pyrano[2,3-c]phenazine]and benzo[α]pyrano[2,3-c]phenazine derivatives under solvent-free conditions

A green,convenient,high yielding and one-pot procedure for the synthesis of novel spiro[benzo[α]pyrano[2,3-c]phenazine]derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-l,4-dione,benzene-l,2-diamines,ninhydrine,and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione(theophylline) as an expedient,eco-friendly and reusable solid base catalyst under thermal,microwave irradiation and solvent-free conditions.This procedure has also been applied successfully for the synthesis of benzo[α]pyrano[2,3-c]phenazines.     

Alkylation of pyrimido[5′,4′:5,6]pyrido[3,2-b]indol-4-one derivatives

Alkylation of 11-benzyl-3,11-dihydro-4H-pyrimido[5′,4′:5,6]pyrido[3,2-b]indol-4-one with methyl iodide and methyl bromoacetate in DMF gave 3-alkylpyrimidopyridoindolones as the corresponding salts. The reaction in acetone in the presence of K₂CO₃ yielded 3,6-disubstitution products. Alkylation with DMF dimethyl acetal gave a mixture of the 3- and 6-alkylpyrimidopyridoindol-4-one bases. The structure of 4-oxo-4,6-dihydro-3H-pyrimido-[5′,4′:5,6]pyrido[3,2-b]indol-11-ium chloride (3b) was proved by X-ray diffraction analysis.     

Novel tocopheryl compounds XXIV. Studies into the nitrosation chemistry of γ-tocopherol: preparation of 5-nitroso-γ-tocopherol via an organomercury derivative of vitamin E

5-Nitroso-γ-tocopherol (5) was not accessible by direct nitrosation of γ-tocopherol (3), but was synthesized for the first time by nitrosation of an organomercurial intermediate (11) under aprotic conditions. Under protic conditions 5 exists in equilibrium with its ortho-quinone monoxime tautomer 6, the latter being the major component with >99%. NMR and analytical data of the tautomeric couple are reported for the first time. The chemistry of the nitrosation of γ-tocopherol was studied in detail. In the presence of oxygen, 5 is readily oxidized to 5-nitro-γ-tocopherol (7), whereas at elevated temperatures an additional process, the conversion of monoxime 6 into 5,6-tocopheryldione (8) under loss of hydroxylamine sets in. The experimental results agreed with the outcome of DFT computations.     

Novel Synthesis of Pyrano[2,3-d]Thiazole,Thiazolo[3,2-a]Pyridine,and Pyrazolo [3′,4′:4,5] Thiazolo[3,2-a]Pyridine Derivatives

Cyclocondensation of 2-cyanomethyl-4-thiazolidinone (1) with tetracyanoethylene (2) furnished pyrano[2,3-d]thiazole derivative (4) . Benzo[e]pyrano[2,3-d]thiazole derivative (6) was obtained by cyclization of compound (1) with salicylaldehyde. In a similar manner, condensation of compound (1) with 2-hydroxy-1-naphthaldehyde in refluxing ethanol yielded naphtho[e]pyrano[2,3-d]thiazole derivative (7) . Interaction of compound (9) with benzylidenemalononitriles (10) (1 : 1 molar ratio) at reflux temperature in ethanol in the presence of piperidine afforded thiazolo[3,2-a]pyridines (12a-c) . Treatment of compound (12a) with hydrazines furnished pyrazolo[3′,4′:4,5] thiazolo[3,2-a]pyridines (14a,b) . The reaction of compound (1) with benzyli-denecyanoacetate (16) yielded 5-hydroxythiazolo[3,2-a]pyridine derivative (21) . Cyclization of bis(thiazolinone) (23) with benzylidenemalononitriles (10) produced bis(thiazolopyridine) derivatives (25a,b) .     

Studies of Thiazolopyridines,Part 6: Synthesis and Antimicrobial Evaluation of Some Novel Thiazolo[3,2-a] Pyridine and Thiazolo[2′,3′:6,1]-pyrido[2,3-d]pyrimidine Derivatives

Condensation of thiazolinone 1 with aromatic aldehydes yielded the corresponding methylidene derivatives 2a–f. Cyclization of compounds 2a–f with arylidenemalononitrile 3 (1:1 molar ratio) in ethanol in the presence of piperidine furnished the novel thiazolo[3,2-a]pyridines 5a–v, via Michael adduct 4. Compounds 5p, r were cyclized with malononitrile in the presence of piperidine to yield thiazolo[3,2-a][1,8]naphthryidines 7a, b. Thiazolo-[2′,3′:1,6]pyrido[2,3-d]pyrimidine 9a–cwere obtained by cyclization of compounds 5c, p, r with formic acid. The structure of the synthesized compounds was established by analytical and spectral data. Also, some of the synthesized compounds were screened for antimicrobial activity in vitro.     

Syntheses with heterocyclic β-enaminonitriles: A facile preparation of polyfunctionally substituted thiophene,thieno[3,2-b]pyridine and thieno[3,2-d]pyrimidine derivatives

Summary A convenientGewald synthesis of 3,5-diaminothiophene-2-carbonitrile derivatives (2) is reported. The synthetic potential of the -enaminonitrile moiety in2 has been explored; it proved to be a promising candidate for the synthesis of polyfunctionally substituted thieno[3,2-b]pyridines and thieno[3,2-d]pyrimidines.

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Synthesen mit heterocyclischen -Enaminonitrilen: Eine einfache Methode zur Herstellung polyfunktionell substituierter Thiophen-, Thieno[3,2-b]pyridin- und Thieno[3,2-d]pyrimidinderivate

Zusammenfassung Eine bequeme Methode zur Herstellung von 3,5-Diaminothiophen-2-carbonitril-Derivaten (2) nachGewald wird vorgestellt. Das synthetische Potential der -Enaminonitrilfunktion von2 wurde untersucht.2 ist ein geeignetes Ausgangsmaterial für die Synthese polyfunktionell substituierter Thieno[3,2-b]pyridine und Thieno[3,2-d]pyrimidine.

     

New approaches to the synthesis of functionally substituted pyrido[3′,2′:4,5]thieno[3,2-b]pyridines and the structure of the products obtained

Substituted pyrido,[3',2':4,5]thieno[3,2-b]pyndines were obtained by the reaction of 3-amino-2-benzoylthieno [2,3-b]pyridines with malononitrile and the reaction of 3-cyanopyridine-2(IH)-thiones with 2-aryl-3-bromo-I,I-dicyanopropene. 2-Amino-4-(4-bromophenyl)-7, 9-dimethyl-3-cyanopyrido [3',2':4,5]thieno[3, 2-b]-pyridine was used for the synthesis of a derivative of pyrido[3",2":4', 5']thieno[2',3':5,6]pyrido[2,3-d]-pyrimidine. The structure of these compounds was confirmed by spectral data and x-ray diffraction structural analysis.Deceased.     

Hydrogenation of arenes by the RhCl3-aliouat® 336 catalyst: Part 2. Reduction of naphthalene derivatives to tetralins

Hydrogenation of naphthalene in the presence of the RhCl₃-Aliquat^® 336 catalyst was investigated. The reaction was shown to take place at 30 °C at atmospheric hydrogen pressure and to give decalin-free tetralin. Methylnaphthalenes, naphthols and ethyl naphthoates were found to be hydrogenated mainly on the non-substituted ring. The naphthols gave tetralones in addition to the expected tetralols. Chlorinated naphthalenes proved to undergo partial hydrogenolysis even before ring hydrogenation. Further reduction of the tetralins to decalins occurred only after complete consumption of the starting material. Cis-hydrogenation was found to be the main stereochemical course of the catalytic process.     

Cyclopenta[b]thienyl ligand in organometallic chemistry. Studies of the regioselectivity of the synthesis of new σ-element-substituted cyclopenta[b]thiophene derivatives

Reactions of 2-ethyl-5-methylcyclopenta[b]thienyllithium (thiopentalenyllithium) (2) with various electrophilic reagents afford σ-element-substituted thiopentalenes. However, the reaction with Ph₃SnCl yields only one of two possible isomers,viz, triphenyl(4H-cyclopenta[b] thiophen-4-yl)stannane (4c), whereas the reactions with Me₃SiCl, Me₃SiCl, or Ph₂PCl give both possible isomers,viz., trimethyl(6H-cyclopenta[b]thiophen-6-yl)silane (3a) and trimethyl(4H-cyclopental[b]thiophen-4-yl)silane (4a), trimethyl(6H-cyclopenta[b]thiophen-6-yl)stannane (3b) and trimethyl(4H-cyclopental[b]thiophen-4-yl)stannane (4b), or diphenyl(6H-cyclopenta[b]thiophen-6-yl)phosphine (3d) and diphenyl(4H-cyclopenta[b]thiophen-4-yl)phosphine (4d) in ratios of 1∶2, 1∶2, or 1∶1, respectively. The structure of compound4c was established by X-ray diffraction analysis. The observed regioselectivity of formation of compound4c is attributed to the specific precoordination of the tin atom by the sulfur atom of the thiopentalenyl ligand and to the steric overcrowding of the Sn atom in organotin electrophiles. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1285–1289, July, 2000.     

Synthesis of derivatives of imidazo[4,5-b]pyridine:Novel sulfur contained side chains for macrolide antibiotics

Two series of novel derivatives of imidazo[4,5-b]pyridine were synthesized.These compounds could be used as side chains of semisynthesised ketolide antibiotics.The side chains have free amine group which can attached to ketolide core.Macrolides with this kind of side chains will show obvious activities against erythromycin-resistant strains.The structure of the side chains was confirmed by ~1H,~(13)C NMR,MS,HMBC spectra.     

A Convenient Synthesis of Novel Functionalized Pyrimido[5′,4′:4,5]thieno[3,2-c]pyridazines and Related Fused Systems

Possible approaches to the synthesis of functionalized, pyrimido[5′,4′:4,5]thieno [3,2-c]pyridazines 2-18 , pyridazino[3′,4′:4,5]thieno[2,3-d]triazines 19, 20a,b and pyrido[3′,2′:4,5]thieno[3,2-c]pyridazines 22a,b are described. The sequence involves the heterocyclization of 6-amino-1,3-diphenyl-1,4-dihydrothieno[3,2-c]pyridazine-7-carboxamide (1) with appropriate reagents. The antimicrobial activity of some the newly synthesized compounds was examined. All tested compounds proved to be active as antibacterial and antifungal agents.     

Synthesis of new pyridazino[4′,3′:4,5]-thieno[3,2-d]-1,2,3-triazine and pyrimido[4′,5′:4,5]thieno[2,3-c]pyridazine derivatives

Summary 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-one (2), 3-substituted 8,9-diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-ones (3a–c), 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-one (4), 8-chloro-3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazine (5), 8-substituted 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazines (6a–h) and 7-substituted 3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-ones(7a–c) were synthesized from 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxamide (1).

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Synthese neuer Pyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-und Pyrimido[4,5:4,5]thieno[2,3-c]pyridazin-Derivate

Zusammenfassung Folgende Verbindungen wurden ausgehend von 5-Amino-3,4-diphenylthieno[2,3-c]pyridazin-6-carboxamid (1) synthetisiert: 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-on (2), 3-substituierte 8,9-Diphenylpyridazino[4,3:4,5]thieno[3,2-d]-1,2,3-triazin-4(3H)-one (3a–c), 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8[7H]-on (4), 8-Chlor-3,4-diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin (5), 8-substituierte 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazine (6a–h) und 7-substituierte 3,4-Diphenylpyrimido[4,5:4,5]thieno[2,3-c]pyridazin-8(7H)-one (7a–c).

     

Condensed pyridopyridimines. 8. Synthesis of new derivatives of pyrano[3’,4’:6,7]pyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine

New substituted 8,8-dimethyl-4-oxopyrano[3,4:6,7]pyrido[2,3-d]pyrimidines have been synthesized from 2-amino-3-ethoxycarbonyl-7,7-dimethylpyrano[4,3-b]pyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, 1554–1557, October, 2004.     

Synthesis of derivatives of the new heterocyclic system pyrimido[4′,5′:4,5]pyrimido[1,2-a]benzimidazole

3-Phenyl-5-methyl(phenyl)-1H,3H-pyrimido[4,5:4,5]pyrimido[1,2-a]benzimi-dazole-2,4-diones were obtained by the cyclization of N-phenyl-N-[3-ethoxycar-bonyl-4-methyl(phenyl)pyrimido [1,2-a]benzimidazol-2-yl]ureas by the action of potassium carbonate. 2-Methyl-5-phenyl-1H-pyrimido[4,5:4,5]pyrimido[1,2-a]benzimidazol-4-one was obtained by the reaction of N-3-ethoxycarbonyl-4-phenylpyrimido[1,2-a]benzimidazol-2-yl]-N,N-dimethylacetamidine with ammonium acetate in ethanol. The synthesized compounds are members of a new heterocyclic system. The molecular and crystal structure of the solvate of 3-phenyl-5-methyl-1H,3H-pyrimido[4,5:4,5] pyrimido[1,2-a]benzimidazole-2,4-dione with two molecules of DMF was studied by x-ray crystallographic analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2587–2592, November, 1991.     

Condensed isoquinolines. 7.* Synthesis of derivatives of the new heterocyclic system thieno[3′,2′:5,6]-pyrimido[1,2-b]isoquinoline

4-Oxo-6, 11-dihydro-4H-thieno[3, 2.-5,6]-pyrinudo[1, 2-b]isoquinolines have been synthesized by the reaction of o-bromo-methylphenylacetonitrile with esters of substituted 2-aminothiophene-3-carboxylic acids. They were characterized as the hydrobromides and as the fee bases. The tautonterism of the bases in DMSO solution is discussed.For Communication 6. see[1].T. G. Shevchenko Kiev University, Kiev, 252017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 366–369, March, 1996. Original article submitted September 9, 1995.