Studies on 5-aminoisoxazole derivatives: Synthesis of some new fused isoxazoles

Several new fused isoxazole derivatives could be obtained utilising 5-amino-4-ethoxycarbonyl-3-ethoxycarbonylmethyl and 5-amino-4-cyano-3-trichloromethyl-isoxazoles as starting components.

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Untersuchungen an 5-Aminoisoxazol-Derivaten: Synthese einiger neuer kondensierter Isoxazole

Zusammenfassung Es konnten einigen neue Isoxazolderivate über 5-Amino-4-ethoxycarbonyl-3-ethoxycarbonylmethyl-und 5-Amino-4-cyano-3-trichlormethyl-isoxazol als Ausgangsverbindungen erhalten werden.

     

Synthesis of some novel heterocyclic dyes derived from pyrazole derivatives

Diazotized aryl amines were coupled with 3-substituted 5-amino pyrazoles to produce a series of novel 3-substituted 5-amino-4-arylazopyrazoles. Also, 3-substituted 5-amino-pyrazoles were diazotized and coupled with different phenols to give the corresponding novel 3-substituted 5-aryl azo pyrazoles. These dyes were characterized by elemental analysis and spectral data, applied to different types of fibres (wool, polyester and a blend of wool/polyester as disperse dyes) and their fastness properties were evaluated.     

Michael addition of N-isobutylidene-t-butylamine to dimethyl methoxymethylenemalonate and a new synthesis of some fused pyrazole derivatives from the adduct

N-Isobutylidenemethylamine reacted with dimethyl methoxymethylenemalonate to afford the N-alkylation product 3a exclusively. Exchanging the N-substituent of the Schiff's base from methyl to t-butyl altered the course of the reaction, allowing Michael addition to take place predominantly. The Michael adduct 4c on reaction with hydrazinoalkanols 6a,b, 6c,d and 6e gave tetrahydropyrazolo[5,1-b]oxazoles 9a,b , tetrahydro-pyrazolo[5,1-b][1,3]oxazines 9c,d and hexahydropyrazolo[5,1-b][1,3]oxazepine 9e , respectively.     

Synthesis,characterization and antibacterial activity of some new pyrazole based Schiff bases

In the present study a series of new Schiff bases were synthesized. All the synthesized compounds were characterized by IR, ¹H NMR, mass spectral and elemental analyses. Newly synthesized compounds were screened for their antibacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) activity. The results revealed that, compounds 3f and 3c have exhibited significant biological activity against the tested microorganisms.     

Design and synthesis of some new tri-substituted pyrazole derivatives as anticancer agents

A new series of tri-substituted pyrazole derivatives were designed as anti-cancer agents and synthesized, starting with the formylation of semicarbazone via the Vilsmeier–Haack reaction to give 3-(4-bromophenyl)-1H-pyrazole-4-carbaldehyde I which was the precursor of compounds 1–9. The new chemical entities were screened for their anti-cancer activity on various human cancer cell lines, namely: hepatocellular carcinoma HepG2, breast cancer MCF-7, lung carcinoma A549 and prostatic cancer PC3. Most of the synthesized compounds showed remarkable activity on the tested cell lines, while compound 2 had the highest potency against the HepG2 cell line with an IC₅₀ of 9.13 µM compared with doxorubicin (IC₅₀ = 34.24 µM), the reference standard used in this study, and compound 7 was the most active on the rest of the three cell lines; MCF-7, A549 and PC3 (IC₅₀ = 16.52, 6.52 and 9.13 µM, respectively) relative to IC₅₀ = 20.85, 5.93 and 38.02 µM of the standard. Thus, some of the synthesized tri-substituted pyrazole derivatives, specially 2 and 7, have the potential to be developed into potent anticancer agents.     

Computational investigation of the structure and antioxidant activity of some pyrazole and pyrazolone derivatives

Pyrazoles and pyrazolones constitute a group of organic compounds that have various medical applications such as antimicrobial, antipyretic, anti-inflammatory, antitumor and antioxidants. Pyrazolones can exist in different isomeric forms (CH, NH, OH) due to keto-enol, lactam-lactim and imine-enamine tautomerism. Determination of the most stable tautomeric form is thus important for understanding their biological roles at the molecular level. We performed a theoretical investigation of the structural and antioxidant properties of three synthetic pyrazolones (1–3), one synthetic pyrazole (4), one natural pyrazole (5) and two engineered hydroxyl derivatives of 1 (7, 8) and of 5 (9, 10) using the density functional theory at the B3LYP/6-311++G(d,p) level of theory in gas phase and in methanol (using the polarizable continuum model). It is found that substituents and solvents may influence the relative stability of pyrazolone isomers and that the CH tautomer is typically the least stable. Vertical ionization potentials, vertical electron affinities and X–H bond dissociation energies (X?=?C, N, O, S) are calculated for the global minimum structures and compared with those of the standard antioxidant flavonoid quercetin (6). Calculations predict that compounds 1 and 5 have antioxidant activity similar to 6 and that their mono and dihydroxyl derivatives (7–10) are more efficient antioxidants. Results also indicate that compounds 1–10 preferably interact with free radicals adopting the H atom transfer rather than the sequential electron transfer proton transfer mechanism. The study gives insight into the structural requirements for the design of highly efficient antioxidants.     

Diethyl acetonedicarboxylate — a precursor for the synthesis of new substituted 4-aminoquinolines and fused 4-aminopyridines

Summary The reaction of cyclic enaminonitriles1 with diethyl acetonedicarboxylate (2) affords fused 4-amino-3-ethoxycarbonyl-2-ethoxycarbonylmethyl-pyridines4. The course of the reaction and the yield of cyclic products were promoted by tin(IV)chloride. N-substituted diethyl 3-aminoglutaconates3 seem to be intermediates of the cyclization reaction.Dedicated to Prof.Milan Kratochvil on the occasion of his 70th birthday     

Synthesis of some new fused coumarin derivatives

2-Hydrazino-4-hydroxy-5H- [1] -benzopyrano- [ 4,3-d ] -pyrim-idin-5-one (3) was prepared via condensation of 2 with hy-drazine hydrate. Treatment of 3 with methylene chloride, ethyl chloroformate, ethyl chloroacetate and benzaldehyde yielded the corresponding 2 - ( substituted ) hydrazino - 4 -hydro-xy-5H-[1]-benzopyrano-[4, 3-d]-pyrimidin-5-one (4, 5, 6, and 10), followed by cyclization of 4, 5 and 6 with dimethyl fonnamide and fused sodium acetate under reflux, while compound 10 was cyclized with bromine and sodium acetate in acetic acid. Compound 3 reacted with β-(toloyl) acrylic acid, ethyl α-cyano-p-methoxytinnamate, diethyl mal-onate and acetyl chloride affording the corresponding 2-(substituted) hydrazino-4-hydroxy-5H-[1]-benzopyrano-[4, 3-d]-pyrimidin-5-one (12, 13, 14, 15 and 16).     

Ketene S,S-acetals in the synthesis of some new fused pyrimidine derivatives

Condensation of ketene dithioacetal derivatives with some aminoazoles (5-aminotetrazole monohydrate, 2-aminobenzimidazole, 2-aminobenzothiazole, and 2-aminothiazole) in the presence or absence of triethylamine gave the corresponding tetrazolopyrimidines, benzimidazopyrimidines, benzothiazolopyrimidines, and thiazolopyrimidines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 469–473, March, 2007.     

Molecular docking studies of some new imidazole derivatives for antimicrobial properties

In modern drug designing, molecular docking is routinely used for understanding drug-receptor interaction. In the present study six imidazole derivatives containing substituted pyrazole moiety (2a,b and 4a–d) were synthesized. Structures of the newly synthesized compounds were characterized by spectral studies. Compounds were screened for their antibacterial activity. Compound 4c was found to be potent antimicrobial against Pseudomonas aeruginosa at concentrations of 1 and 0.5 mg/mL compared to standard drug Streptomycin. All the compounds were subjected to molecular docking studies for the inhibition of the enzyme l-glutamine: d-fructose-6-phosphate amidotransferase[GlcN-6-P] (EC 2.6.1.16). The in silico molecular docking study results showed that, all the synthesized compounds having minimum binding energy and have good affinity toward the active pocket, thus, they may be considered as good inhibitor of GlcN-6-P synthase.     

A versatile synthesis of fused triazolo derivatives by sequential Ugi/alkyne-azide cycloaddition reactions

We report a facile synthesis of fused dihydrotriazolo[1,5-a]pyrazinones and triazolobenzodiazepines by an Ugi/alkyne-azide cycloaddition synthetic sequence. The coupling of the Ugi multi-component reaction with the intramolecular alkyne-azide cycloaddition provides access to highly functionalized heterocyclic ring systems in two steps from easily available starting materials in excellent overall yields.     

Solid-phase synthesis of 1,2-benzophenazine and some fused imidazole derivatives

The solid-phase synthesis of 1,2-benzophenazine and various N-methylbenzimidazoles using o-diaminoarenes is very promising and permits the synthesis of 1-methyl-4,5-[b]naphtho-1H-imidazole, which could not be obtained by the condensation of o-diaminoarenes with paraformaldehyde using the standard liquid-phase method.M. V. Lomonosov Moscow State University, 119899, Moscow, Institute for Synthetic Polymer Materials, 117461, Moscow, and Institute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, 1424432, Moscow Oblast. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 672–674, May, 1996. Original article submitted April 3, 1996.     

Practical synthesis of bicyclic pyrazol-5-one derivatives

This communication describes a convenient synthesis of fused bicyclic pyrazolones in a one-pot reaction procedure. Modified protocols are also developed to access 5,5-bicyclic and bulky pyrazolones in good yields. The method reported herein represents a practical approach to structurally diversified bicyclic pyrazolones.     

Regioselective synthesis of thiophene fused sultam derivatives via iodocyclization approach and their application towards triazole linker

An efficient regioselective synthesis of 4-iodo-2,3-disubstituted-2H-thieno[3,2-e][1,2]thiazine-1,1-dioxide derivatives via iodocyclization approach using iodine under mild reaction condition described herein. This coupling–iodocyclization strategy tolerated a variety of functional groups such as alkyl, cycloalkyl, phenyl producing the six-membered heterocyclic ring selectively. The resulting 4-iodo-2,3-disubstituted-2H-thieno[3,2-e][1,2]thiazine-1,1-dioxide was coupled with a variety of boronic acids (Suzuki coupling) and activated alkenes (Heck coupling). The iodo group was utilized for Sonogashira coupling followed by efficient transformation to azido precursor, which was used for the synthesis of various thieno-sultam linked with triazole.     

Studies on the synthesis of heterocyclic compounds. Part IV. Further investigation of the pschorr reaction with some pyrazole derivatives

Thermal decomposition of the diazonium sulfate derived from N-methyl-(1-phenyl-3-methylpyrazol-5-yl)-2-aminobenzamide afforded products formulated as 1-phenyl-3-methyl[2]benzopyrano[4,3-c]pyrazol-5-one (yield 10%), 1,4-dimethyl-3-phenylpyrazolo[3,4-c]isoquinolin-5-one (yield 10%), N-methyl-(1-phenyl-3-methylpyrazol-5-yl)-2-hydroxybenzamide (yield 8%) and 4′-hydroxy-2,3′-dimethyl-1′-phenylspiro[isoindoline-1,5′-[2]-pyrazolin]-3-one (yield 20%). Decomposition of the diazonium sulfate derived from N-methyl-(1,3-diphenylpyrazol-5-yl)-2-aminobenzamide gave products formulated as 7,9-dimethyldibenzo[e,g]pyrazolo[1,5-a][1,3]-diazocin-10-(9H)one (yield 8%), 4-methyl-1,3-diphenylpyrazolo[3,4-c]isoquinolin-5-one (yield 7%) and 4′-hydroxy-2-methyl-1′,3′-diphenylspiro[isoindoline-1,5′-[2]pyrazolin]3-one (yield 10%). The spiro compounds 6a,b underwent thermal and acid-catalysed conversion into the hitherto unknown 2-benzopyrano[4,3-c]pyrazole ring system 7a,b in good yield. Analytical and spectral data are presented which supported the structures proposed.     

Target-based design,synthesis and biological activity of new pyrazole amide derivatives

Based on the similarities in the conformation of VS008 (N-(4-methylphenyl)-3-(tert-butyl)-1-(phenylmethyl)-1H-pyrazole-5-carboxamide) and BYIO6830 (N'-(3,5-dimethylbenzoyl)-N'-tert-butyl-5-methyl-2,3-dihydro-1,4-benzodioxine-6-carbohydrazide) bound to the active site of the EcR subunit of the ecdysone receptor (EcR)-ultraspiracle protein (USP) heterodimeric receptor, a series of new pyrazole amide derivatives were designed and synthesized. Their structures were confirmed by IR, ¹H NMR, ¹³C NMR and elemental analysis. Results from a preliminary bioassay revealed that two of the pyrazole derivatives exhibited promising insecticidal activity. Specifically, compounds 6e and 6i exhibited good activity against Helicoverpa armigera (cotton bollworm) at low concentration. Symptoms displayed by tebufenozide-treated H. armigera were identical with those displayed by its treated counterpart. 6i showed the same poisoning symptoms as those of tebufenozide. In addition, results from molecular docking result indicated that the binding modes of 6e and 6i at the active site of the EcR subunit of the heterodimeric receptor were similar to that of the bound tebufenozide.     

Reaction of 5-aminopyrazole derivatives with ethoxymethylene-malononitrile and its analogues

A one-pot synthesis using 5-aminopyrazole derivatives 1 with ethoxymethylenemalononitrile (EMMN), ethyl ethoxymethylenecyanoacetate (EMCA) or diethyl ethoxymethylenemalonate (DEMM) gave pyrazolo-[1,5-a]pyrimidine compounds 2,4,8 . Also, the one step reaction of EMCA with hydrazine hydrate afforded ethyl(4-ethoxycarbonyl-5-pyrazolyl)aminomethylenecyanoacetate 3c . On the other hand, the reaction of 1-substituted 5-aminopyrazole-4-carboxamide 9 with EMMN afforded pyrazolo[3,4-d]pyrimidine compounds 10 .     

Catalyst-free green synthesis and study of antioxidant activity of new pyrazole derivatives

In this research, a novel procedure for the synthesis of pyrazole derivatives in excellent yields was studied using catalyst-free multicomponent reaction of isoquinoline, activated acetylenic compounds, alkyl bromides, triphenylphosphine and hydrazine in water under ultrasonic irradiation at room temperature. The advantages of this procedure than to reported methods are short time of reaction, high yields of product, easy separation of product, clean mixture of reaction and green media for performing reaction. In addition, because of having pyrazole and isoquinoline core in the synthesized compounds, in this research, antioxidant activity of some synthesized compounds was investigated.     

Synthesis of some fused quinoline derivatives

Summary Preparations of the novel fused dimethoxyquinoline derivatives of furo[2,3-b]quinoline (5),s-triazolo[4,3-a]quinoline (8) and tetrazolo[1,5-a]quinoline (10) from 6,7-dimethoxy-3-car-boxyquinoline-1-oxide (1) are reported.

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Synthese kondensierter Chinolinderivate

Zusammenfassung Die Synthese der neuen kondensierten Dimethoxy-Chinolinderivate Furo[2,3-b]chinolin (5),s-Triazolo[4,3-a]chinolin (8) und Tetrazolo[1,5-a]chinolin (10) aus 6,7-Dimethoxy-3-carboxychinolin-1-oxid (1) wird beschrieben.