L-prolinammide supportata su polistirene come organocatalizzatore altamente enantioselettivo nella reazione aldolica diretta

Supported ionic liquid asymmetric cathalysis. A new method for chiral catalyst recycling

A new method for chiral catalysts recycling, based on the supported ionic liquid asymmetric catalysis concept, has been developed. This concept involves the treatment of a monolayer of covalently attached ionic liquid on the surface of silica gel with additional ionic liquid. These layers serve as the reaction phase in which the homogeneous chiral catalyst is dissolved. As first application of this concept the L-proline-catalyzed aldol reaction has been carried out. Good yields and ee values, comparable with those obtained under homogeneous conditions have been obtained. Moreover, this material shows high regenerability.

Cyclodextrins: heterocyclic molecules able to perform chiral recognition (Part II)

The present paper collects the most significant advances appeared since late 1998 up to June 2005 in the field of applications of natural and modified cyclodextrins as chiral selectors, with particular regard for pharmaceuticals and natural products.

Polarimetric study of binding equilibria between cyclodextrins and some suitable organic guests

Oxidative degradation properties of Co-based catalysts in presence of ozone

Supported ionic liquids. New recyclable materials for L-proline-catalyzed aldol reaction

Stereoselective synthesis: from organoselenium to organocatalysis

A joint experimental and computational study on the oxidative cyclization of aldehyde thiosemicarbazones induced by potassium ferricyanide and by tris(p-bromophenyl)amino hexachloroantimoniate.

New recyclable materials for L-proline-catalyzed aldol reactions

Spectrophotometric study on the thermodynamics of binding of α- and β-cyclodextrin towards some p-nitrobenzene derivatives

Binding properties of native alpha- and beta-cyclodextrin towards some nitrobenzene derivatives have been studied by means of UV-vis spectrophotometry. The former host is able to form complexes having 1 : 1 and 1 : 2 stoichiometric ratios with these guests, while only 1 : 1 complexes are detected with the latter host. A careful analysis of the thermodynamic parameters for complexation equilibria, under the perspective of the enthalpy-entropy compensation effect, reveals that binding abilities of the two different hosts are subject to different features.

Complexation equilibria between beta-cyclodextrin and p-nitroaniline derivatives in mixed solvent media: a polarimetric study

Polarimetry as a useful tool for the study of binding equilibria between cyclodextrins and some suitably sized and structured organic molecules

Effect of linear 5-alkyl substituents on the rearrangement rate of the Z-phenylhydrazones of some 5-alkyl-3-benzoyl-1,2,4-oxadiazoles

Z-Phenylhydrazones of 3-benzoyl-1,2,-oxadiazole: investigation of behaviour in solution and in the gas phase.

Catalytic properties of Ag-PolyaminoβCD NPs for reduction of nitroarenes

The reduction of nitroarenes is a key reaction involved in the synthesis of several compounds such as drugs, pesticides or dyes. During the last years Pd and Ag NPs have been used as catalysts to carry out this reaction with NaBH4. However several mechanistic aspects of the process are still unclear; in particular there is not agreement about the kinetic order of these reactions, whether 0-th or 1-st order in the substrate[1]. The aim of this work is to use a novel catalytic systems constituted by Ag-NPs coated with different polyamino-βCDs (Figure 1)[2], to carry out the reduction of some aromatic nitrocompounds using NaBH4 as the reducing agent, and to determine the kinetic features of th…

As the change in ternary agent structure influence the chiral recognition ability of pyrene/heptakis-(6-amino)-(6-deoxy)-b-cyclodextrin

Short and efficient chemoenzymatic synthesis of goniothalamin

Binding properties of polyaminocyclodextrin materials towards polyanions and p-nitroaniline derivatives

Beta-cyclodextrin as host for the rearrangement of some Z-hydrazones of 3-benzoyl-5-X-1,2,4-oxadiazoles.

Binding properties of mono-6-amino-beta-cyclodextrin towards p-nitroaniline derivatives: a polarimetric study

Photochemical preparation of polyaminocyclodextrin-capped silver nanocomposites: mechanistic insights

Photoreduction of silver salts in the presence of three polyaminocyclodextrin derivatives (AmCD, Figure 1) constitutes a simple and straightforward route to obtain stable Ag nanoparticles. These systems have been suitably characterized (UV-vis, FT-IR, TEM, Figure 2) and tested for their antimicrobial activity.1 We observed that Ag photoreduction is effectively induced by irradiation with green light (513 nm); however, best performances are achieved with the use of a light source having at the same time a significant emission in the near-infrared (NIR) region. On the grounds of analytical and kinetic evidences, we hypothesized a multi-step mechanism for nanoparticle formation. In particular,…

Binary complexes heptakis-(6-amino)-(6-deoxy)-beta-cyclodextrin/fluorophore: structural investigation and chiral recognition

Enantioselective recognition of alfa-amino acids by binary complexes fluorophore/cyclodextrin

Studio polarimetrico degli equilibri di inclusione tra ciclodestrine native ed opportuni guest modello alifatici e aromatici

New proline derivatives as recyclable catalysts for aldol reaction

Binding porperties of hetpakis-(2,6-di-O-methyl)-beta-cyclodextrin and mono-(3,6-anydro)-beta-cyclodextrin

Polystyrene supported L-proline: a recyclable organocatalyst for the asymmetric aldol reaction in the presence of water

Nanoparticelle di Ag-poliamminoCD come catalizzatori per la riduzione di nitrocomposti aromatici

Sistemi nanoparticellari di Argento protetti con poliammino-beta-ciclodestrine sono stati preparati, caratterizzati, e impiegati come catalizzatori per la riduzione con boroidruro di sodio di una serie di nitrocomposti aromatici modello 1-8. Tale reazione costituisce una interessante alternativa rispetto ai metodi di riduzione più comuni (LiAlH4, Zn/HCl), che prevedono l’uso di condizioni di reazione piuttosto drastiche. La cinetica della reazione considerata è stata approfonditamente studiata al fine di chiarire il ruolo meccanicistico del catalizzatore. E’ stato trovato, infatti, che il processo risulta di ordine misto rispetto al substrato, e che le costanti cinetiche apparenti di reazio…

L-Prolina supportata su polistirene come catalizzatore eterogeneo nella reazione di condensazione aldolica “in the presence of water”