Catalyse dans l'eau en présence de cyclodextrine native ou modifiée (Application au couplage croisé de type Suzuki)

Depuis quelques années, les acteurs du secteur de la chimie se sont donnés pour mission prioritaire de concevoir des produits et des procédés chimiques plus respectueux de l environnement afin de répondre aux préoccupations environnementales. Ainsi, les douze principes du concept de la chimie verte sont nés. L un de ces principes est de substituer, lors des synthèses, les solvants organiques, généralement toxiques, par des solvants plus éco-compatibles comme l eau et d un point de vue plus général, la catalyse joue un rôle majeur dans cette politique de chimie verte puisqu elle permet de réduire la consommation d énergie, de diminuer la quantité des réactifs utilisés ainsi que les procédés de séparation par augmentation de la sélectivité. Cependant, la faible solubilité dans l eau des substrats organiques ne permet pas l obtention de bons rendements. Afin de pallier ce problème, la catalyse par transfert de phase inverse peut être utilisée. La synthèse de nouveaux catalyseurs organométalliques solubles dans l eau a donc été envisagée. Ces catalyseurs seront dérivés de cyclodextrine et pourront également assurer le transport du substrat en phase aqueuse par reconnaissance supramoléculaire.For a few years, the priority task for actors of the chemical field has been the design of greener products and greener chemical processes to meet the environmental concerns. Thus, the twelve principles of the green chemistry were set. One of them is to substitute toxic organic solvents for more eco-compatible solvents, such as water, during chemical synthesis. More generally speaking, catalysis plays a significant role in this green chemistry policy as it enables to enhance energy saving, to reduce the quantity of the used compounds and to reduce as well the separation processes by increasing the selectivity. However, the low solubility of organic substrates in water prevents from having profitable yields. To tackle the issue, the catalysis by inverse phase transfer can be used. Therefore, the synthesis of new water soluble organometallic catalysts was considered. These catalysts will be derivates of cyclodextrin and will allow carrying the substrate in aqueous phase by supramolecular recognition.COMPIEGNE-BU (601592101) / SudocSudocFranceF

Ordering of Saturated and Unsaturated Lipid Membranes near Their Phase Transitions Induced by an Amphiphilic Cyclodextrin and Cholesterol

When inserted in membranes of dimyristoyl phosphatidylcholine (DMPC), methylated β-cyclodextrins with one (TrimβMLC) or two (TrimβDLC) lauryl acyl chains grafted onto the hydrophilic cavity exert a "cholesterol-like ordering effect", by straightening the acyl chains in the fluid phase at temperatures near the chain melting transition. This effect may be related to pretransitional events such as the "anomalous swelling" known to occur with saturated phosphatidylcholine membranes. To investigate this model, order profiles and bilayer thicknesses of DMPC and unsaturated 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) membranes containing amphiphilic cyclodextrins or cholesterol were determined by deuterium NMR. The pure lipid membranes display both a qualitatively similar chain ordering upon cooling in the fluid phase, more important at the chain extremity, which gets more pronounced near their fluid-to-gel transitions. Both membranes show a bilayer thickness increase by ∼0.5 Å just above their transition, as observed previously with saturated phosphatidylcholines of various chain lengths. Membrane-insertion of 5% TrimβMLC or cholesterol induces an important ordering of the DMPC acyl chains just above the transition, which is also more pronounced at the chain extremity. There is an additional increase of the bilayer thickness, most probably due to a deep insertion of these amphiphilic molecules, facilitated by increased bilayer softness in the anomalous swelling regime. These effects are more important with TrimβMLC than with cholesterol. By contrast, no enhanced acyl chain ordering was observed when approaching the transition of TrimβMLC-containing POPC membranes, as a possible consequence of an eventual lack of anomalous swelling in unsaturated lipid membranes. Insertion of higher concentrations of TrimβMLC was found to induce a magnetic orientation of the DMPC membranes in the fluid phase with 10% of this derivative, coupled with the appearance of a broad isotropic component when the concentration is raised to 20%. No membrane orientation or isotropic component was detected with TrimβMLC-containing POPC membranes

A green approach to the synthesis of novel phytosphingolipidyl β-cyclodextrin designed to interact with membranes

This work reports the synthesis of a new family of mono-substituted amphiphilic cyclodextrins using a green methodology. Reactions using greener and safer catalysts with more environmentally friendly purification solvents were performed. Four unreported mono-substituted cyclodextrins bearing a phytosphingolipidyl chain and a fatty acid chain (C10, C12, C14 and C18) were successfully obtained with a promising yield

Enantioselectivity improvement induced by β-cyclodextrin in the NaBH4 reduction of acetophenone through the formation of a three-component inclusion β-cyclodextrin–acetophenone–triethylamine complex

International audienc

A Combined Approach of NMR and Mass Spectrometry Techniques Applied to the α-Cyclodextrin/Moringin Complex for a Novel Bioactive Formulation †

Moringin, obtained via enzymatic conversion of the glucosinolate precursor glucomoringin, is an uncommon member of the isothiocyanate class, and has been proven to possess a broad range of biological activities such as antitumor activity, protection against neurodegenerative disorders and bactericidal effects. Since moringin is weakly soluble in water and unstable in aqueous medium, cyclodextrins (CDs) were considered for the development of a new moringin formulation, with a view to improving its solubility and stability in aqueous solution for use as an anti-inflammatory. A combined structural study using proton nuclear magnetic resonance (1H-NMR), diffusion-ordered spectroscopy (DOSY) and ion mobility mass spectrometry (IM-MS) is reported, highlighting the formation of a 1:1 α-CD/moringin inclusion complex. The association constant K was determined (1300 M−1 at 300 K). Completion of the structural characterization was performed by T-ROESY and MS/MS experiments, which evidenced the mode of penetration of moringin into α-CD. Finally, the “chaperone-like” properties of α-CD with respect to the stability of moringin have been highlighted

Oligosaccharide tagged β-cyclodextrins: synthesis and biological affinity towards Concanavalin A

6 páginas, 2 figuras, 5 esquemas.An original synthetic route based on multi-glycosylation and selective protection–deprotection steps has been developed which allows a fast access to complex oligomannosides with both α-(1,3),α-(1,6) and α-(1,3),α-(1,4) cores. The later have been linked to modified β-cyclodextrins bearing spacing arms of varying chemical structure and length through peptidic-like coupling, leading to the formation of a range of oligomannosyl cyclodextrin conjugates. Complexation studies with sodium anthraquinone-2-sulfonate (ASANa) and sodium adamantane 1-carboxylate (ACNa) as guest molecules demonstrated that the β-cyclodextrin inclusion properties are preserved. Binding affinity studies using the mannose specific lectin Concanavalin A (Con A) demonstrated the key role of the density and tridimensional structure of the sugar ligand in recognition events.This work was supported by the Conseil Régional de Picardie under the scientific IBFBio program.Peer reviewe

Oligosaccharide tagged β-cyclodextrins: synthesis and biological affinity towards Concanavalin A

6 páginas, 2 figuras, 5 esquemas.An original synthetic route based on multi-glycosylation and selective protection–deprotection steps has been developed which allows a fast access to complex oligomannosides with both α-(1,3),α-(1,6) and α-(1,3),α-(1,4) cores. The later have been linked to modified β-cyclodextrins bearing spacing arms of varying chemical structure and length through peptidic-like coupling, leading to the formation of a range of oligomannosyl cyclodextrin conjugates. Complexation studies with sodium anthraquinone-2-sulfonate (ASANa) and sodium adamantane 1-carboxylate (ACNa) as guest molecules demonstrated that the β-cyclodextrin inclusion properties are preserved. Binding affinity studies using the mannose specific lectin Concanavalin A (Con A) demonstrated the key role of the density and tridimensional structure of the sugar ligand in recognition events.This work was supported by the Conseil Régional de Picardie under the scientific IBFBio program.Peer reviewe

Regioselective access to 3 I -O-substituted-β-cyclodextrin derivatives

International audienc

Aqueous Catalytic Hydrogenation and Hydroformylation Reactions Promoted by Highly Water-Soluble Amphiphilic Cyclodextrins Bearing Oleic Grafts

International audienc