Synthesis and molluscicidal activity of new chromene and pyrano[2,3-c]pyrazole derivatives

The chromene derivative 4 reacts with acetic anhydride, phenylisothiocyanate and ethyl orthoformate to afford the N-acetyl derivative 6, the chromenopyrimidine 8 and the formimidate 9, respectively. 2-(1H-Indol-3-ylmethylene)-malononitrile 10b reacts with 1,3-cyclohexanedione and dimedone 11a, b to afford the 4(3-indolyl)-chromene derivatives 12a, b respectively, and with the pyrazolone derivatives 13a-d to afford the arylidene exchange derivatives 14a-c and the pyranopyrazole derivative 15, respectively. The arylidene derivatives 10a, b react also with indane-1,3-dione 16 to afford the arylidene exchange derivatives 18a, b. The molluscicidal activity of the synthesized compounds towards Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni, was investigated and most of them showed weak to moderate activity.     

Synthesis and molluscicidal activity of new cinnoline and pyrano [2,3-c]pyrazole derivatives

2-(3-Hydroxy-5,5-dimethylcyclohexylidene)malononitrile 5 undergoes an azo coupling reaction with aryldiazonium salts to afford 3-amino-2-aryl-6,6-dimethyl-8-oxo-2,6,7,8-tetrahydrocinnoline-4-carbonitriles 7. Upon reflux in acetic acid, these compounds were acetylated to give the cinnoline derivatives 9. The pyrazolones 10a, b react with 3-furfurylidene- and 3-thienylidene-malononitrile derivatives 11a, b to afford the pyrano[2,3-c]pyrazole derivatives 13a-d. These newly synthesized compounds show generally a moderate molluscicidal activity to Biomphalaria alexandrina snails.     

Reactions with acetoacetanilide: Synthesis and antibacterial activity of some new pyran,pyrano[2,3-c]pyrazole and pyrano[2,3-c]-pyridine derivatives

The reaction of acetoacetanilide (1) with the α-cyanocinnamonitrile derivatives2 yielded the Michael adducts4 which could be converted into the pyrano[2,3-c] pyrazole derivatives5 via their reaction with hydrazine hydrate. Cyclisation of4 afforded the cyanoaminopyrans9 which could in turn be converted into the corresponding pyridine derivatives10. The pyranopyrazoles9 reacted with different activated nitrile derivatives (3a-c) to give the pyrano[2,3-c]pyridine derivatives13, 16 and19 respectively. The biological activity of the synthesised heterocyclic derivatives was investigated and discussed.     

Synthesis and molluscicidal activity of some 1,3,4-triaryl-5-chloropyrazole, pyrano[2,3-c]pyrazole, pyrazolylphthalazine and pyrano[2,3-d]thiazole derivatives

2-(5-Chloro-1,3-diphenyl-1H-pyrazol-4-ylmethylene)-malononitrile 1a reacts with the arylidenes of malononitrile 2a-d to afford the triaryl-5-chloropyrazoles 3a-d, respectively. 1a reacts with the active methylene pyrazolinones 5a, b and 12a, b to afford different products 8, 9, 10, 11, and 14a, b--depending on the substitution in the pyrazole ring. Compound 1a reacts also with the pyridazinone derivative 15 to afford the phthalazinone 16, and with the thiazolinones 17a-c to afford the pyrano[2,3-d]thiazoles 20a-c, respectively. It reacts also with the malononitrile dimer 21a and with ethyl cyanoacetate dimer 21b to yield the pyrazolyl pyridines 22a, b, respectively. The synthesized compounds showed a moderate molluscicidal activity towards Biomphalaria alexandrina snails.     

Rapid and efficient ultrasound-assisted method for the combinatorial synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives

An efficient one-pot synthesis of spiro[indoline-3,4'-pyrano[2,3-c]pyrazole] derivatives by four-component reaction of hydrazine, β-keto ester, isatin, and malononitrile or ethyl cyanoacetate catalyzed by piperidine under ultrasound irradiation is described. This synthesis was confirmed to follow the group-assistant-purification chemistry (GAP) chemistry process, which can avoid traditional chromatography and recrystallization purifications.     

Multicomponent synthesis of poly-substituted benzo[a]pyrano[2,3-c]phenazine derivatives under microwave heating

A new one-pot two-step tandem synthesis of highly functionalized benzo[a]pyrano[2,3-c]phenazine derivatives via microwave-assisted multicomponent reactions of 2-hydroxynaphthalene-1,4-dione, diamines, aldehydes, and malononitrile is reported. The procedures are facile, avoiding time-consuming and costly syntheses, tedious workup, and purifications of precursors, as well as protection/deprotection of functional groups. The method is expected to find application in the combinatorial synthesis of biologically active compounds, since phenazine and chromene motifs have a broad spectrum of biological activities.     

Synthesis and antimicrobial evaluation of naphtho[2,1-b]pyrano[2,3-d]pyrimidine and pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives

Several novel naphtho[2,1-b]pyrano[2,3-d]pyrimidines, pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines and their coumarin-3-yl derivatives were synthesized. Some of these derivatives exhibited pronounced antimicrobial activities.     

Ultrasound promoted green synthesis of spiro[pyrano[2,3-c]pyrazoles] as antioxidant agents

Ultrasound promoted, cerium ammonium nitrate catalyzed sustainable synthesis of spiro[indoline3,4′-pyrano[2,3-c]pyrazole] derivatives (4a–l) is reported herein. The synthesized compounds were screened for their antioxidant activities as free radical scavenging effect on diphenylpicryl hydrazine (DPPH^?), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS^?+) and nitric oxide (NO) radicals. The screened compounds showed potent scavenging activities against DPPH^?, ABTS^?+ and NO radicals. In order to further extend on studies and to obtain a deep insight into structure activity relationship of this class of compounds, we designed N-substitution of indole moiety with the aim to study its antioxidant potential.     

Synthesis and antimicrobial activities of novel naphtho[2,1-b]pyran, pyrano[2,3-d]pyrimidine and pyrano[3,2-e][1,2,4]triazolo[2,3-c]-pyrimidine derivatives

The synthesis of new naphtho[1',2':5,6]pyrano[2,3-d]pyrimidines and related heterocycles has been reported. The key intermediate 3-amino-8-bromo-1-(p-methoxyphenyl)-1H-naphtho[2,1-b] pyran-2-carbonitrile (3c) was obtained in one pot synthesis by treating alpha-cyanocinnamonitrile (1c) with 6-bromo-2-naphthol (2). Antimicrobial activity was shown for some of the synthesized compounds.     

Synthesis and anticonvulsant activity of pyrano[4′,3′:4,5]pyrido[2,3-b]thieno[3,2-d] pyrimidine derivatives and pyrimido[5′,4′:2,3]-thieno[2,3-c]isoquinoline derivatives

Methods for the synthesis of condensed thieno[3,2-d]pyrimidines based on pyrano[4,3-d]thieno[2,3-b]pyridines and thieno[2,3-b]isoquinolines have been developed and a series of new derivatives have been synthesized. The anticonvulsant activity of the synthesized compounds has been studied. Several compounds possessing specific anticonvulsant activity with respect to corazole-induced convulsions are revealed. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 9, pp. 14–16, September, 2007.     

Design and synthesis of some thieno[2,3-c]pyridazine derivatives of expected anticancer activity

Design and synthesis of some new thienopyridazine derivatives as anticancer agents were the goal of this work. Accordingly, a series of novel compounds were synthesized via reacting thienopyridazine carboxylic acid hydrazide with different organic reagents. Twelve novel compounds were selected by National Cancer Institute for a full anticancer screening assay where seven of the investigated compounds showed non-selective broad spectrum and promising activity almost against all cancer cell lines. One of the most active compounds was chosen to be evaluated against 60-cell line panel at five concentration levels and revealed a remarkable growth inhibition activity.     

Novel derivatives of benzo[b]thieno[2,3-c]quinolones: synthesis, photochemical synthesis, and antitumor evaluation

Novel derivatives of benzo[b]thieno[2,3-c]quinolones 3a-j were synthesized in a multistep synthesis starting from substituted benzo[b]thiophene-2-carbonyl chlorides, to their corresponding benzo[b]thiophene-2-carboxamides, which were photochemically dehydrohalogenated to their corresponding substituted benzo[b]thieno[2,3-c]quinolones. Compound 4 was prepared from 3i by alkylation with 3-dimethylaminopropyl chloride in the presence of NaH. Compounds 7a,b were prepared from 3g in the multistep synthesis from compounds 5 and 6. Compounds 3b, 3c-f, 3h, 7a, and 7b were found to exert cytostatic activity against malignant cell lines: pancreatic carcinoma (MiaPaCa2), breast carcinoma (MCF7), cervical carcinoma (HeLa), laryngeal carcinoma (Hep2), colon carcinoma (CaCo-2), melanoma (HBL), human fibroblast cell lines (WI-38). The compounds that bear a 3-dimethylaminopropyl substituent on the quinolone nitrogen (3b, 3c-f, 3h) showed higher antitumor activity than compounds bearing the same substituent on the amidic nitrogen (7a and 7b). The compound 3h, which has a 3-dimethylaminopropyl substituent on the quinolone nitrogen and a methoxycarbonyl substituent at position 9, had marked antitumor activity. Because of strong cytotoxic effect of compound 4 on melanoma cells (HBL, ME 67.3, and ME 67.1), a potential mechanism of action was examined. Analysis of DNA and Annexin-V-FLUOS staining indicated that compound 4 causes cell death by apoptosis.     

Synthesis and antidepressant activity of 4-aryltetrahydrothieno[2,3-c]pyridine derivatives

A series of substituted 4-aryltetrahydrothieno[2,3-c]pyridines was prepared by acid-catalyzed cyclization of 1-aryl-2-[(2-thienylmethyl)amino]ethanol derivatives. The compounds were examined for their antidepressant activity, as demonstrated by their ability to inhibit the uptake of norepinephrine (NE) and serotonin (5-HT) and to prevent tetrabenazine-induced ptosis (TBZ) in mice. Significant inhibition of both neurotransmitters is observed for several of the tested compounds, while some of them are selective inhibitors of either NE or 5-HT uptake. Optimal activity is associated with the introduction of lipophilic substituents into the 4-position of the phenyl ring and less lipophilic substituents into the 2-position of the thiophene ring (11, 23). Compound 33 bearing substituents in positions 2 and 6 of the phenyl ring is inactive. This might be a consequence of an out of plane conformation of this compound.     

Microwave-assisted CAN-catalyzed solvent-free synthesis of N-allyl quinolone-based pyrano[4,3-b]chromene and benzopyrano[3,2-c]chromene derivatives and their antimicrobial activity

A new series of pyrano[4,3-b]chromene and benzopyrano[3,2-c]chromene derivatives have been synthesized via microwave-assisted one-pot, three-component reaction of N-allyl quinolones, cyclic β-diketones, and 4-hydroxy-6-methyl-2H-pyran-2-one/4-hydroxy coumarin in the presence of catalytic amount of ceric ammonium nitrate under solvent-free condition. The protocol offers expeditious and solvent-free synthesis with excellent yield to furnish fused chromenes for their antimicrobial activity. The chemical structures of the synthesized compounds were elucidated by ¹H NMR, ¹³C NMR, FT-IR, elemental analysis, and mass spectral data. All the compounds were screened against a representative panel of pathogenic strains by broth micro dilution minimum inhibitory concentration method. Among these derivatives, compounds 6i, 6k, 6l, and 6m were found to have admirable activity when compared to the standard drugs.