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- Copper(II) complexes with an arylhydrazone of methyl 2-cyanoacetate as effective catalysts in the microwave-assisted oxidation of cyclohexanePublication . Jlassi, Raja; Da Costa Ribeiro, Ana Paula; Alegria, Elisabete; Naili, Houcine; Tiago, Gonçalo; Rueffer, Tobias; Lang, Heinrich; Zubkov, Fedor; Pombeiro, Armando; Rekik, WalidReaction of sodium (E/Z)-2-(2-(1-cyano-2-methoxy-2-oxoethylidene) hydrazinyl) benzene-sulfonate (NaHL) with copper(II) nitrate hydrate in the presence of imidazole (im) in methanol affords [CuL(im)(H2O)] (1). Complex 1 is characterized by IR spectroscopy and ESI-MS spectrometry, elemental and single crystal X-ray crystal structural analyses. The coordination environment of the central copper(II) is nearly intermediate between ideal square-based pyramidal and trigonal bipyramidal geometry, three sites being occupied by the L2- ligand, which chelates in the O, N, O fashion, while two other sites are filled with the water and imidazole molecules. Extensive intermolecular hydrogen bonds between the L2-, water and imidazole ligands lead to a 3D supramolecular network. 1 and known Cu(II) complexes [Cu(H2O)(2)L]center dot H2O (2), [Cu(H2O)(py)L]center dot H2O (3) and [Cu-3(mu(3)-OH)(NO3)(CH3OH)(mu(2)-X)(3)(mu(2)-HL)] (4) act as effective catalysts in the oxidation of cyclohexane to cyclohexanol and cyclohexanone, using low power microwave (MW) irradiation, under mild conditions. Without a promoter, the activity of the catalyst reached a turnover number of 1.44 x 10(3) and a turnover frequency of 1.98 x 10(3) h(-1), after 2 h, at 50 degrees C. (C) 2017 Elsevier B.V. All rights reserved.
- Elementary and efficient catalyst process for the Knoevenagel condensation of araldehydes with arylmethylidene malononitrilePublication . Jlassi, Raja; Da Costa Ribeiro, Ana Paula; Tiago, Gonçalo; Wang, Jiawei; Krawczyk, Marta S.; Martins, Luisa; Naili, Houcine; Pombeiro, Armando; Rekik, WalidA comparative study of the Knoevenagel condensation of an aromatic aldehyde with an active methylene compound (e.g., malononitrile or ethyl cyanoacetate), using solvent free grindstone conditions and microwave irradiation is reported. Our solvent free approaches led these reactions to proceed faster, more cleanly and in higher yields. Moreover, they also allowed the use of nitrobenzaldehydes, which failed to yield the desired products under traditional and water based approaches. Thus, an efficient procedure for the Knoevenagel condensation of aryl and heteroaromatic aldehydes with malononitrile. using the complex [CdNa2(mu-L-2)](n)center dot 6.34H(2)O or commercial CdO as catalyst under solvent-free and very mild conditions has been developed. (C) 2017 Elsevier B.V. All rights reserved.