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Zeghada S.,Faculte Des Science Of Luniversite | Bentabed-Ababsa G.,Faculte Des Science Of Luniversite | Bentabed-Ababsa G.,French National Center for Scientific Research | Derdour A.,Faculte Des Science Of Luniversite | And 6 more authors.
Organic and Biomolecular Chemistry | Year: 2011

Reactions were performed from aryl azides on the one hand, and activated alkenes coming from β-dicarbonyl compounds or malonodinitrile on the other hand, either with recourse to conventional heating or to microwave activation, to afford 1-aryl-1H-1,2,3-triazoles. The mechanism and the regioselectivity of the reactions involving β-dicarbonyl compounds have been theoretically studied using DFT methods at the B3LYP/6-31G* level: they are domino processes comprising a tautomeric equilibrium of the β-dicarbonyl compounds with their enol forms, a 1,3-dipolar cycloaddition of the enol forms with the aryl azides (high activation energy), and a dehydration process (lower activation energy). The effect of non-conventional activation methods on the degradation of 1,2,3-triazolines was next studied experimentally. Finally, some of the 1,2,3-triazoles such synthesized were evaluated for their bactericidal and cytotoxic activities. © 2011 The Royal Society of Chemistry.

Bentabed-Ababsa G.,University of Rennes 1 | Bentabed-Ababsa G.,Faculte Des Science Of Luniversite | Ely S.C.S.,University of Rennes 1 | Hesse S.,Institut Universitaire de France | And 5 more authors.
Journal of Organic Chemistry | Year: 2010

(Chemical Equation Presented) All pyridine nitriles and esters were metalated at the position next to the directing group using (TMP) 3CdLi in tetrahydrofuran at room temperature. The 2-, 3-, and 4-cyanopyridines were treated with 0.5 equiv of base for 2 h to afford, after subsequent trapping with iodine, the corresponding 3-iodo, 2-iodo, and 3-iodo derivatives, respectively, in yields ranging from 30 to 61%. Cyanopyrazine was similarly functionalized at the 3 position in 43% yield. Ethyl 3-iodopicolinate and -isonicotinate were synthesized from the corresponding pyridine esters in 58 and 65% yield. Less stable ethyl 4-iodonicotinate also formed under the same conditions and was directly converted to ethyl 4-(pyrazol-1-yl)nicotinate in a two-step 38% yield. All three ethyl iodopyridinecarboxylates were involved in a one-pot palladium-catalyzed cross-coupling reaction/cyclization using 2-aminopyridine to afford new dipyrido[1,2-a:3′,2′-d]pyrimidin-11- one, dipyrido[1,2-a:4′,3′-d]pyrimidin-11-one, and dipyrido[1,2-a:3′,4′-d]pyrimidin-5-one in yields ranging from 50 to 62%. A similar crosscoupling/ cyclization sequence was applied to methyl 2-chloronicotinate using 2-aminopyridine, 2-amino-5-methylpyridine, and 1-aminoisoquinoline to give the corresponding tricyclic or tetracyclic compounds in 43-79% yield. Dipyrido[1,2-a:4′,3′-d]pyrimidin-11-one and dipyrido[1,2-a:3′,4′-d]pyrimidin-5-one showed a good bactericidal activity against Pseudomonas aeroginosa. Dipyrido-[1,2-a:2′,3′-d] pyrimidin-5-one and pyrido[2′,3′:4,5]pyrimidino[2,1-a]isoquinolin-8- one showed a fungicidal activity against Fusarium and dipyrido[1,2-a:4′, 3′-d]pyrimidin-11-one against Candida albicans. Ethyl 4-(pyrazol-1-yl) nicotinate and dipyrido[1,2-a:2′,3′-d]pyrimidin-5-one have promising cytotoxic activities, the former toward a liver carcinoma cell line (HEPG2) and the latter toward a human breast carcinoma cell line (MCF7). © 2009 American Chemical Society.

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