First Sustainable Aziridination of Olefins Using Recyclable Copper-Immobilized Magnetic Nanoparticles
Toumieux, S.; Khodadadi, M.; Pourceau, G.; Becuwe, M.; Wadouachi, A.
Synlett 2019, 30, 563-566.
The first copper-catalyzed aziridination of olefins using recyclable magnetic nanoparticles is described. Magnetic nanoparticles were modified with dopamine and used as a support to coordinate copper. The methodology was optimized with styrene as olefin and using [N-(p-toluenesulfonyl)imino]phenyliodinane (PhI=NTs) as nitrene source. A microwave irradiation decreased the reaction time by 4-fold compared to conventional heating method. The catalyst was recovered by simple magnetic extraction and could be reused successfully up to five times without significant loss of activity. The methodology was applied to a range of different olefins leading to moderate to excellent yields in the formation of the expected aziridine.
http://dx.doi.org/10.1055/s-0037-1611717

Nitroxide supported on nanometric metal oxides as new hybrid catalysts for selective sugar oxidation
Omri, M.; Becuwe, M.; Davoisne, C.; Pourceau, G.; Wadouachi, A.
J. Colloid Interface Sci. 2019, 536, 526-535.
A new series of supported organocatalysts, prepared by a simple method, were used for selective sugar oxidation. This approach is based on the immobilization of a nitroxide derivative through a carboxylic function on nanometric metal oxides (TiO2, Al2O3 and CeO2), allowing the recovery of the catalyst. These hybrid materials were carefully characterized by Diffuse Reflectance FT-IR spectroscopy (DRIFT), ThermoGravimetric Analysis (TGA), X-Ray Diffraction (XRD), Brunauer-Emmet-Teller surface area measurements (B.E.T.), elemental and electrochemical analyses, showing different characteristics and behaviors depending on the nature of the metal oxide used. The activity of the supported nitroxide catalyst was evaluated on methyl α-d-glucoside oxidation, used as model reaction. In all cases, high catalytic activity was highlighted, with up to 25 times less nitroxyl radical required for complete conversion than under homogeneous conditions. The influence of several experimental conditions such as the use of phosphate buffer and recyclability of the catalyst were also investigated.
http://dx.doi.org/10.1016/j.jcis.2018.10.065

New iodide-based amino acid molecules for more sustainable electrolytes in dye-sensitized solar cells
Sagaidak, I.; Huertas, G.; Nguyen Van Nhien, A.; Sauvage, F.
Green Chem. 2018, 20, 1059-1064.
The electrolyte is the second key component governing at once power conversion performances and stability of dye-sensitized solar cells. Towards the integration of more sustainable materials, we focused in the replacement of the major constituent of the electrolyte, namely the 1,3 di-alkyl imidazolium iodide. We synthesized two new iodide molecules derived from natural amino acid family (L-proline): (S)-2-(methoxycarbonyl)-1,1-dimethylpyrrolidinium iodide (PMeI) and (S)-2-(ethoxycarbonyl)-1,1-ethylpyrrolidinium iodide (PEtI). In combination with the C106 polypyridyl ruthenium(+II) sensitizer, power conversion efficiencies of 7.1% for PMeI and 6.5% for PEtI were obtained under standard Air Mass 1.5G conditions in conjunction with low-volatile 3-methoxypropionitrile-based solvent. The relationship between these new iodide molecules, the power conversion efficiency and interfacial charge transfer processes is herein discussed and systematically compared to the best standard 1,3 di-methylimidazolium iodide.
http://dx.doi.org/10.1039/c7gc03429f

Gold Catalysis and Photoactivation: A Fast and Selective Procedure for the Oxidation of Free Sugars
Omri, M.; Sauvage, F.; Busby, Y.; Becuwe, M.; Pourceau, G.; Wadouachi, A.
ACS Catalysis 2018, 1635-1639.
A fast and efficient methodology for the selective oxidation of sugars into corresponding sodium aldonates is herein reported. Hydrogen peroxide was used as a cheap oxidant and electron scavenger, in the presence of only 0.003-0.006 mol % of gold in basic conditions. Three photocatalysts were studied, namely Au/Al2O3, Au/TiO2 and Au/CeO2, the latter being the most efficient (TOF > 750 000 h-1) and perfectly selective. Only 10 minutes exposition under standard incident sunlight irradiation (A.M.1.5G conditions - 100 mW/cm2) affords total conversion of glucose into the corresponding sodium gluconate. Demonstrating its versatility, this methodology was successfully applied to a variety of oligosaccharides leading to the corresponding aldonates in quantitative yield and high purity (>95%) without any purification step. The photocatalyst was recovered by simple filtration and re-used 5 times leading to the same conversion and selectivity after 10 min of illumination.
http://dx.doi.org/10.1021/acscatal.7b03394