Condensed Pyridine Bases. Synthesis and Reactions of Benzofuro[2,3-c]indeno[2,1-e]-, Benzothieno[2,3-c]Indeno[2,1-e]-, Benzofuro-[3,2-c]Indeno[2,1-e]- and Thieno[2,3:4′,5′]-thieno[3,2-c]indeno[2,1-e]pyridines

Condensation of hetarene carboxaldehydes with phthalide gave 2-(3-hydroxy-1-oxoinden-2-yl)benzo[b]furan and 2-(3-hydroxy-1-oxoinden-2-yl)-5-ethylthieno[2,3-b]thiophene. Starting from hetaryl acetic acids gave 3-(3-hydroxy-1-oxoinden-2-yl)benzo[b]furan and 3-(3-hydroxy-1-oxoinden-2-yl)benzo[b]thiophene. Acylation of 3-hydroxy-1-oxoinden-2-yl-substituted heterocycles using acetic anhydride in the presence of 70% HClO₄ leads to the formation of pentacyclic pyrilium salts. Pentacyclic indenopyridines are prepared by treating the pyrilium salts with ammonia. The reaction of the carbonyl group in the indenopyridines with hydroxylamine, hydrazine hydrate, and in reduction using NaBH₄ has been studied.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 435–443, March, 2005.     

A straightforward synthesis of pyrimido[4,5-b]quinoline derivatives assisted by microwave irradiation

Several pyrimido[4,5-b]quinolines, flavin analogues, have been prepared by assisted microwave intramolecular cyclization of N⁴-substituted-2,4-diamino-6-chloropyrimidine-5-carbaldehydes. The reaction takes place with hydrolysis of amino-group and chlorine. Particularly valuable features of this method included the broader substrate scope and operational simplicity as well as increased safety for small-scale high-speed synthesis.     

Synthesis and molecular structure of 4-nitro-9-phenyl-1H-and 9-hydroxy-3-oxo-9-phenyl-2,3-dihydro-9H-indeno-[2,1- c ]pyridines and 3,7-diphenyl-3a, 4,5,6-tetrahydroindeno[2,1- c ]isoxazolo[5,4- d ]pyridine

The 4-nitro derivatives and an oxidation by-product, 9-hydroxy-2-methyl-3-oxo-9-phenyl-2,3-dihydro-9H-indeno[2,1-c]pyridine were obtained by the nitration of N-alkyl-9-phenyl-2,3-dihydro-1H-indeno-[2,1-c]pyridines with sodium nitrite in acetic acid. Their molecular structures were studied by X-ray structural analysis. The product of [2+3] cycloaddition, 5-methyl-3,7-diphenyl-3a, 4,5,6-tetrahydroindeno[2,1-c]isoxazolo[5,4-d]pyridine, was obtained by the interaction of 2-chloro-1-hydroxy-2-phenylazomethine with 2-methyl-9-phenyl-2,3-dihydro-1H-indeno[2,1-c]pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1390–1399, September, 2007.     

Synthesis of condensed heterocycles containing a pyrimido[5,4-e][1,3]-thiazine fragment

The cyclocondensation of 4,6-dichloro-2-methylthiopyridine-5-carbaldehyde and heterocyclic thiones such as 1,2,4-triazole-5-thione, imidazolidine-2-thione, imidazole-2-thione, and 4,5-diphenylimidazole-2-thione in dimethylformamide gave tricyclic heterocycles containing a pyrimido[5,4-e][1,3]thiazine fragment. The reaction of 6-chloro-8-methylthio-5H-pyrimido[5,4-e][1,2,4]triazolo[5,1-b][1,3]thiazin-5-ol with diethylamine, pyrrolidine, and morpholine gave the corresponding 6-dialkylaminopyrimidotriazolothiazines.Vilnius University, 2006 Vilnius, Lithuania; e-mail: sigitas.tumkevicius@chf.vu.lt. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 854–856, June, 2000.     

在离子液体中一步法合成吡唑[5,4-b]-γ-吡喃衍生物

芳醛、丙二腈与4,5-二氢-3-甲基-5-氧代-1-苯基吡唑在离子液体[bmim][BF₄]中反应, 合成了2-氨基-4-芳基-3-氰基-5-甲基-7-苯基吡唑[5,4-b]-γ-吡喃衍生物, 该法快速、高效, 是一种洁净的合成方法. 产物的结构通过红外光谱、核磁共振氢谱和元素分析进行表征.     

One-pot synthesis of furo[2,3-h]quinoline and furo[2,3-h]isoquinoline derivatives using Fischer carbene complex

A new route for the synthesis of furo[2,3-h]quinoline and furo[2,3-h]isoquinoline derivatives have been explored through the coupling of carbene complexes with pyridine-bridged enynes. This reaction process, involving the annulation of both furan and benzene ring on to a pre-existing pyridine ring is highly efficient in the presence of triphenylphosphine as ligand additive.     

水介质中三组分一锅合成1-芳基苯并[f]喹啉衍生物

以芳醛、2-萘胺和Meldrum酸为原料, 以水为溶剂, 在回流条件下以三乙基苄基氯化铵为催化剂通过三组分一锅反应, 合成了一系列的1-芳基苯并[f]喹啉衍生物. 该方法具有反应条件温和、产率较高(79%～87%)、环境友好等优点. 产物的结构通过熔点, IR, ¹H NMR和元素分析表征.     

Highly efficient synthesis of pyrimido[4,5-d]pyrimidine-2,4-dione derivatives catalyzed by iodine

A new and efficient synthesis of pyrimido[4,5-d]pyrimidine-2,4-dione derivatives through the reaction of 6-aminouracils and N,N′-bis(arylmethylidene) arylmethane in the presence of molecular iodine as a readily available and feasible catalyst.     

Study of nitrogen- and sulfur-containing heterocycles. 54. Properties and conversions of pyrimido[4,5-<Emphasis Type="Italic">b</Emphasis>]-1,4-benzothiazepines. Synthesis of a novel heterocyclic system: Pyrimido[5,4-<Emphasis Type="Italic">c</Emphasis>]isoquinoline

We have studied some properties and conversions of pyrimido[4,5-b]-1,4-benzothiazepines: reduction, oxidation, reactions with nucleophilic reagents (methanol, hydrazine, hydroxylamine, o-methylhydroxylamine, and thiosemicarbazide). We have synthesized derivatives of a novel heterocyclic system: pyrimido[5,4-c]isoquinoline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1863–1872, December, 2004.For Communication 53, see [1].     

Alternative synthesis and novel oxidizing ability of 6,9-disubstituted cyclohepta[b]pyrimido[5,4-d]pyrrole-8(6H),10(9H)-dione derivatives

Synthesis of 6,9-disubstituted cyclohepta[b]pyrimido[5,4-d]pyrrole-8(6H),10(9H)-diones 7a-g was accomplished by ring opening and ring closure sequences of 9-substituted cyclohepta[b]pyrimido[5,4-d]furan-8,10(9H)-dione derivatives induced by several amines. Furthermore, alternative synthetic methodology for compounds 7a-e was also accomplished by single-step reaction of 2-chlorotropone with 6-aminouracil derivatives under mild conditions. X-ray crystal analysis of 7a was carried out to clarify the structural characteristics. The properties of 7a-e were studied by the UV-vis spectra and reduction potentials (−1.24 to −1.39 V vs Ag/AgNO₃). Novel photo-induced oxidation reaction of 7a-d toward some amines under aerobic conditions was carried out to give the corresponding imines in more than 100% yield [based on compounds 7a-d], suggesting the oxidation reaction occurs in an autorecycling process.     

A novel and efficient synthesis of pyrimido[4,5-d]pyrimidine-2,4,7-trione and pyrido[2,3-d:6,5-d] dipyrimidine-2,4,6,8-tetrone derivatives

An efficient and direct procedure for the synthesis of pyrimido[4,5-d]pyrimidine-2,4,7-trione derivatives has been described under microwave-assisted conditions. Reaction of 6-amino-1,3-dimethyluracil with aromatic aldehydes resulted in the formation of pyrido[2,3-d:6,5-d] dipyrimidine-2,4,6,8-tetrone derivatives.     

1,3-Dipolar Cycloaddition of Ethyl Propiolate to 4,4-Dimethyl-4,5-dihydro-1,2-dithiolo-[5,4-c]quinoline-1-thiones

The interaction of ethyl propiolate with 4,4-dimethyl-4,5-dihydro-2,3-dithiolo[3,4-c]quinoline-1-thiones leads to 1,3-dithiol-2-ylidenes, 1,6,6a(l4)-trithiapentalene, or thiino[2,3-c]quinolines depending on the conditions.     

A new entry to the substituted pyrrolo[3,2-c]quinoline derivatives of biological interest by intramolecular heteroannulation of internal imines

New 1,3,4-substituted pyrrolo[3,2-c]quinoline derivatives were synthesised in good yields by oxidative heteroannulation of internal imines starting from easily prepared substituted 5-(2-aminophenyl)pyrroles and commercially available aryl and heteroaryl aldehydes. The reaction occurs as a one-pot process involving an intramolecular acid catalysed reaction.     

Microwave assisted synthesis of novel Hantzsch 1,4-dihydropyridines, acridine-1,8-diones and polyhydroquinolines bearing the tetrazolo[1,5-a]quinoline moiety and their antimicrobial activity assess

Microwave assisted efficient Hantzsch reaction via four-component coupling reactions of tetrazolo[1,5-α]quinoline-4-carbal-dehyde, dimedone/cyclohexane-1,3-dione,ethyl/methyl acetoacetate and ammonium acetate was described as the preparation of tetrazolo[1,5-α]quinoline based 1,4-dihydropyridines,acridine-1,8-diones and polyhydroquinolines.The process presented here is simple,rapid,environmentally welcoming and high yielding.All the derivatives were subjected to an in vitro antimicrobial screening against a representative panel of bacteria and fungi and results worth further investigations.     

Synthesis and reactions of 2-[3-(trifluoromethyl)phenyl]furo[3,2-<Emphasis Type="Italic">c</Emphasis>]pyridine

(E)-3-{5-[3-(Trifluoromethyl)phenyl]furan-2-yl}propenoic acid (I) was prepared from 5-[3-(tri-fluoromethyl)phenyl]furan-2-carbaldehyde under the Doebner’s conditions. The obtained acid was converted to the corresponding azide II, which was cyclized by heating in diphenyl ether to 2-[3-(trifluoromethyl)phenyl]-4,5-dihydrofuro[3,2-c]pyridin-4-one (III). This compound was aromatized with phosphorus oxychloride to chloroderivative IV which was reduced with H₂NNH₂-Pd/C to the title compound V. 2-[3-(Trifluoromethyl)phenyl]furo[3,2-c]pyridin-5-oxide (VI) was synthesized by reaction of V with 3-chloroperoxybenzoic acid in dichloromethane. On treatment of VI with benzoyl chloride and potassium cyanide (Reissert-Henze reaction), corresponding 2-[3-(trifluoromethyl)phenyl]furo[3,2-c]pyridine-1-carbonitrile (VII) resulted. 5-Amino-2-[3-(trifluoromethyl)phenyl]furo[3,2-c]pyridin-5-ium-4-methylbenzene sulfonate (VIII) was prepared by direct N-amination of the title compound V with 1-[(aminooxy)sulfonyl]-4-methylbenzene in dichloromethane. Then, VIII was transformed to a non-isolated zwitterionic N-imid IX which afforded the corresponding furo[3,2-c]pyrazolo[1,5-a]pyridine carboxylic acid esters X, XI by 1,3-dipolar cycloaddition reactions with dimethyl but-2-ynedionate (DBD) or ethyl propiolate. The structures of all compounds were confirmed by their IR and NMR spectra. Presented at the 1st International Conference “Applied Natural Sciences” on the occasion of 10th anniversary of the University of St. Cyril and Methodius, Trnava, 7–9 November 2007.     

Studies on 6-[(dimethylamino)methylene]aminouracil: a facile one-pot synthesis of novel pyrimido[4,5-d]pyrimidine derivatives

The reactions of 6-[(dimethylamino)methylene]aminouracil 1, with various heterocumulenes such as aryl isocyanates and isothiocyanates give rise to novel pyrimido[4,5-d]pyrimidines in excellent yields, after elimination of dimethylamine from the (1:1) cycloadducts and tautomerisation. This procedure provides a convenient method for direct synthesis of pyrimido[4,5-d]pyrimidine derivatives under thermal conditions.     

Synthesis of Some NewPyrimido[5,4-a]Indolizines

Summary.  The synthesis of new pyrimido[5,4-a]indolizines by reaction of 2-aminoindolizine-1-carbonitrile or ethyl 2-aminoindolizine-1-carboxylate with various electrophilic reagents is described. The structure of the products was confirmed by their elemental analysis and IR, ¹H NMR, and mass spectra. The results of a preliminary antimicrobial screening are also presented. Received February 4, 2000. Accepted (revised) March 8, 2000