- Graphene Oxide as a Carbocatalyst for a Diels–Alder Reaction in an Aqueous Medium
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The Diels–Alder (DA) reaction, a [4+2] cycloaddition reaction, is highly important in synthetic organic chemistry and is frequently used in the synthesis of natural products containing six-membered rings. Herein, we report an efficient protocol for the DA reaction between 9-hydroxymethylanthracene and N-substituted maleimides using two-dimensional graphene oxide (GO) as a heterogeneous carbocatalyst in an aqueous medium at room temperature. High yields, a wide substrate scope, low temperature, excellent functional group tolerance, atom economy, and water as a green solvent are noteworthy features of this protocol. The heterogeneous GO catalyst can be easily recovered and used multiple times without any significant loss in catalytic activity.
- Girish, Yarabhally R.,Pandit, Subrata,Pandit, Subhendu,De, Mrinmoy
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p. 2393 - 2398
(2017/09/11)
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- Antifungal, cytotoxic and SAR studies of a series of N-alkyl, N-aryl and N-alkylphenyl-1,4-pyrrolediones and related compounds
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The synthesis, in vitro evaluation and SAR studies of 67 maleimides and derivatives acting as antifungal agents are reported. A detailed SAR study supported by theoretical calculations led us to determine that: an intact maleimido ring appears to be necessary for a strong antifungal activity, dissimilarly affected by the substituents in positions 2 and 3. The best activities were shown by 2,3-nonsubstituted followed by 2,3 dichloro- and 2-methyl-substituted maleimides. They all were fungicide rather than fungistatic enhancing the importance of their antifungal activity. 2,3-Dimethyl and 2,3-diphenyl-maleimides possessed marginal or null activity. The presence of a flexible connecting chain in N-phenylalkyl maleimides appears not to be essential for antifungal activity, although its length shows a correlation with the antifungal behavior, displaying maleimides with alkyl chains of n = 3 and n = 4 the best antifungal activities in most fungi. Different substituents on the benzene ring did not have a clear influence on the activity. Values of chemical potential properties as well as of energy do not sufficiently discriminate between active and inactive compounds. Nevertheless, it was found that, although log P alone is not strong enough to properly predict the antifungal activity, the comparison of its values for compounds within the same sub-type, showed an enhancement of antifungal activity along with an increment of lipophilicity. In addition, the LUMO's electronic clouds of the highly active compounds showed to be concentrated on the imido ring, indicating that their carbon atoms are potential sites for nucleophilic attack. Same results were obtained from MEPs. Most of the active compounds did not show cytotoxic activity against human cancer cell lines and no one possessed hemolytic activity, indicating that their activity is selective to pathogenic fungi and that they are not toxic at MIC concentrations.
- Sortino,Garibotto,Cechinel Filho,Gupta,Enriz,Zacchino
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experimental part
p. 2823 - 2834
(2011/06/21)
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- N-Phenyl and N-phenylalkyl-maleimides acting against Candida spp.: Time-to-kill, stability, interaction with maleamic acids
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N-Phenyl and N-phenylalkyl maleimides (alkyl chain = (CH2)n; n = 0-4) and their respective open derivatives (maleamic acids) were evaluated against Candida spp. with the microbroth dilution method following the guidelines of CLSI (formely NCCLS). MIC values of maleimides without pre-incubation and submitted to different pre-incubation times into the growth media, time-to-kill studies as well as a time-dependent UV-spectroscopy study of the maleimides in water, led to determine that maleimides display antifungal activities with their intact maleimide ring, being in addition their activities not dependent on the length of the alkyl chain. They are not only fungistatic but fungicidal with very low MICs and MFCs, displaying strong fungicide activities not only against standardized but also clinical isolates of Candida albicans and non-albicans Candida spp.
- Sortino, Maximiliano,Cechinel Filho, Valdir,Correa, Rogerio,Zacchino, Susana
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p. 560 - 568
(2008/09/18)
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- In vitro antifungal properties, structure-activity relationships and studies on the mode of action of N-phenyl, N-aryl, N-phenylalkyl maleimides and related compounds
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The synthesis, in vitro antifungal evaluation and structure-activity relationship studies of 14 compounds of the N-phenyl-, N-aryl-, N-phenylalkyl- maleimide and 3,4-dichloromaleimide series are reported. The compounds were evaluated against a panel of standardized yeasts and filamentous fungi as well as clinical isolates of Candida albicans. The activities of N-phenylalkyl-3,4- dichloromaleimide derivatives but not those of N-phenylalkyl-maleimide derivatives showed to be dependent on the length of the alkyl chain. N-Phenylpropyl-3,4-dichloromaleimide showed the broadest spectrum of action and lower minimal inhibitory concentrations (MIC) in all of the fungi tested. The nitrogen-carbon distance between the two rings seems to play an important role in the antifungal behavior of these compounds. The most active structure showed inhibited (1,3)β-D-glucan and chitin synthases, enzymes that catalyze the synthesis of the major fungal cell-wall polymers. ECV · Editio Cantor Verlag, Aulendorf (Germany).
- Lopez, Silvia N.,Castelli, Maria V.,De Campos, Fatima,Correa, Rogerio,Cechinel Filho, Valdir,Yunes, Rosendo A.,Zamora, Miguel A.,Enriz, Ricardo D.,Ribas, Juan C.,Furlan, Ricardo L. E.,Zacchino, Susana A.
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p. 123 - 132
(2007/10/03)
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- SAR and 3D-QSAR studies on thiadiazolidinone derivatives: Exploration of structural requirements for glycogen synthase kinase 3 inhibitors
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The 2,4-disubstituted thiadiazolidinones (TDZD) are described as the first ATP-noncompetitive GSK-3 inhibitors. Following an SAR study about TDZD, different structural modifications in the heterocyclic ring aimed to test the influence of each heteroatom o
- Martinez, Ana,Alonso, Mercedes,Castro, Ana,Dorronsoro, Isabel,Gelpí, J. Luis,Luque, F. Javier,Pérez, Conceptión,Moreno, Francisco J.
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p. 7103 - 7112
(2007/10/03)
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- Enzyme inhibitors
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Compounds of general formula (I): where A, E, G, X, Y and the bond - - - take various meanings are of use in the preparation of a pharmaceutical formulation, for example in the treatment of a disease in which GSK-3 is involved, including Alzheimer's disea
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Page/Page column 13
(2010/01/31)
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- 3-Azabicyclo[3.1.0]hexane derivatives useful in therapy
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Compounds of formula (I), their salts and prodrugs thereof, where the substituents are as defined herein are disclosed as opiate binding agents useful in the treatment of opiate-mediated conditions. Also described are processes for making such substances.
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- Antibacterial activity of N-phenylmaleimides, N-phenylsuccinimides and related compounds. Structure-activity relationships
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The antibacterial activity of several phyllanthimide analogs were investigated by the Minimum Inhibitory Concentration Method (MIC) against E. coli and S. aureus. It was found that maleimides were approximately 30 times more active than succinimides indicating that the cyclic imido double bond is an important factor related to the activity. Electron-donor and electron-withdrawing substituents in the aromatic ring of N-phenylmaleimides decrease the activity of these compounds indicating the possibility of steric effects. The distance between the aromatic and the imido rings when separated by methylene groups does not affect the antibacterial activity.
- Cechinel Filho,Pinheiro,Nunes,Yunes,Bella Cruz,Moretto
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p. 675 - 677
(2007/10/02)
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