Bandeau SYMAC

Ionic liquids

To avoid conventional solvents, we use ionic liquids which offer the advantage of immobilizing the catalytic species and allow easy extraction of the reaction products, with a low metal content, interesting for obtaining products of pharmacy interest (Metallic nanoparticles in ionic liquids. Applications in catalysis, Chapter 5 in Nanomaterials in Catalysis, Eds. K. Philippot and P. Serp, Wiley, 2013).

With regard to the homogeneous systems (based on organometallic complexes), the enantioselective allylic substitution reaction (alkylation, amination and sulfonylation) catalysed by palladium in ionic liquids gave excellent TOF (> 20000 h-1), in the presence of chiral P-donor ligands (diphosphites containing carbohydrate skeletons and diamidophosphites ligands). When the solvent is a pyrrolidium salt, effective recycling with negligible palladium levels in the product are obtained (<0.1 ppm) (Chem. Commun. 2011, 47, 7869 ; Organometallics 2014, 33, 771). Remarkable activities and selectivities were observed for the allylic substitution reactions, with bidentate ligands (diphosphites) or ligands with a topology adapted to the medium (Tetrahedron 2011, 67, 421).

For molybdenum-based systems we have developed mono and bimetallic complex dioxomolybdène (VI) with oxazoline ligands, active in epoxidation reactions of substrates, allowing their immobilization in ILs environments (Appl. Catal. A 2011, 398, 88 ; Curr. Inorg. Chem. 2011, 1, 131). Only the bimetallic system induces excellent diastereoselectivity for the epoxidation of (R) -limonène. Mechanistic studies, including NMR-95Mo (Magn. Reson. Chem. 2009, 47, 573), helped to understand the metal-olefin interaction and lack of stereoselectivity in [BMI] [NTf2].

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The use of glycerol represents a green approach to the synthesis of organometallic complexes, metal nanoparticles and catalytic materials in general (Chem. Eur. J. 2014, DOI : 10.1002/chem.201403534).

This solvent is particularly interesting for applications in catalysis because it has a low cost, non-toxicity, high boiling point (290 ° C), a negligible vapor pressure (<1 mm Hg at 293 K), a high solubilizing capacity (except non-polar compounds) and a low miscibility with other organic solvents.

Palladium nanoparticles immobilized in glycerol are highly active in coupling reactions, hydrogenation (Adv. Synth. Catal. 2013, 355, 3648), and one-pot processes (tandem, cascade, sequential). The catalyst can be recycled more than ten times without loss of activity, with a negligible content of palladium in the organic product, and more recently the application of these systems for the synthesis of heterocycles in one-pot conditions has been developed.

Cu2O nanoparticles are active in azoture-alkyne cycloaddition (AAC) by reaction with the terminal alkyne and the benzylazoture or by approach with three components, the simultaneous mixing of the alkyne, sodium azoture and bromide benzyl corresponding (ChemCatChem. 2014, DOI : 10.1002/cctc.201402214).

The catalytic phase of Cu2ONPs was recycled more than ten times without loss of efficiency. Because of its ability to catalyze the C-N and AAC couplings, Cu2ONPs system could be applied in tandem process leading to multifunctional products in high yields.

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The collaboration with the team of Prof. M. Pericàs (ICIQ, Tarragona) as part of a thesis under joint supervision enables the development of metallic systems tailored to glycerol for their applications in enantioselective catalysis. Original chiral ligands "glycerol-soluble" are being synthesized. We develop a stereoselective synthetic route to chiral ligands derived from the PTA having substituents on the carbon atom close phosphorus, functionalization upper rim; at present, only the resolution of mixtures of diastereomers is known. These ligands may be bidentate introducing imidazole or phosphine groups. Subsequent quaternization, if necessary, can increase the solubility in the glycerol environment.