Silvio Quici

Copper-catalyzed aerobic oxidation of alcohols under fluorous biphasic conditions

A catalytic amount of perfluoroalkyl substituted bipyridine 1 (2 mol%), CuBr·Me2S (2 mol%) and TEMPO (3.5 mol%) allow the oxidation of various alcohols to aldehydes and ketones in a fluorous biphasic system of chlorobenzene and perfluorooctane directly with oxygen. The catalyst can be used for several reaction runs without a loss of reactivity.

Copper-catalysed aerobic oxidation of alcohols using fluorous biphasic catalysis

Abstract A copper(I) catalysed and TEMPO mediated fluorous biphasic oxidation of primary, secondary, allylic and benzylic alcohols with oxygen in the presence of a bipyridine ligand bearing perfluorinated ponytails is described. High chemoselectivities are observed in the oxidation of substituted cyclohexanols (substituted axial cyclohexanols react 6–8 times faster than the corresponding equatorial cyclohexanols).

PERFLUOROCARBON-SOLUBLE CATALYSTS AND REAGENTS AND THE APPLICATION OF FBS (FLUOROUS BIPHASE SYSTEM) TO ORGANIC SYNTHESIS

Abstract The new phase-separation and immobilization technique known as FBS (fluorous biphase system) is becoming more and more popular among researchers in both industry and academia. The immiscibility of perfluorocarbons with most organic solvents and water is of great advantage, in that it allows the easy recovery and recycling of the catalysts and reagents. The major results so far obtained in this field are discussed.

Metal Complexes of a Tetraazacyclotetradecane Bearing Highly Fluorinated Tails: New Catalysts for the Oxidation of Hydrocarbons under Fluorous Biphasic Conditions

Abstract The commercially available macrocycle tetraazacyclotetradecane (cyclam) has been converted into the fluorocarbon soluble ligand 1 by N-functionalization with RFCH2OCH2CH2OTs 3, wherein RF is a (per)fluorooxyalkylenic chain. Upon complexation with 1, transition metal salts can be selectively solubilized in fluorocarbons thus providing new catalysts for the oxidative functionalization of hydrocarbons under fluorous biphasic (FB) conditions.

PALLADIUM-CATALYZED HECK REACTION IN PERFLUORINATED SOLVENTS

Abstract Palladium-catalyzed coupling reaction of aryl iodides with methyl acrylate, commonly designated as the Heck reaction, can be performed in perfluorinated solvents, using perfluorocarbon-soluble triarylphosphines as ligands. The easy separation and recycling of the catalyst is also possible.

Hydrolytic kinetic resolution of terminal epoxides catalyzed by fluorous chiral Co(salen) complexes

Abstract Cobalt complexes of fluorous chiral salen ligands have been synthesized and tested as catalysts in the hydrolytic kinetic resolution of terminal epoxides. Whereas the activity of heavily fluorinated complexes was found to be rather low, a ‘light fluorous’ complex was shown to be an efficient and highly selective catalyst for this asymmetric ring-opening reaction. Several strategies for the isolation of reaction products and the recovery of the fluorous catalyst are also discussed.

Synthesis of perfluoroalkylated bipyridines — New ligands for oxidation reactions under fluorous triphasic conditions

Abstract Fluorous soluble bipyridines bearing two perfluoroalkylated side chains in the 6,6′- or 4,4′-positions have been prepared in good yields via etherification of 6,6′-bis(chloromethyl)-2,2′-bipyridine or C -alkylation of 6,6′-dimethyl-2,2′-bipyridine. The new ligands L exhibit amphiphilic behaviour with respect to certain fluorous-organic biphasic systems. Nevertheless, their ruthenium complexes (RuL n )X generated in situ are efficient catalysts for the epoxidation of trans -stilbene in a fluorous triphasic system CH 2 Cl 2 /H 2 O/C 8 F 18 in the presence of NaIO 4 . The fluorous phase, where (RuL n )X is trapped, can be used up to four times without major loss of catalytic activity.

Synthesis, characterization, absorption spectra, and luminescence properties of multinuclear species made of Ru(II) and Ir(III) chromophores.

A series of new mixed-metal Ru(II)-Ir(III) trinuclear complexes have been prepared and characterized, together with their mononuclear parents and a series of closely related dinuclear and trinuclear homometallic Ru(II) and Ir(III) species, and their absorption spectra and luminescence properties (both at 77 K in rigid matrix and at room temperature in fluid solution) have been studied. The absorption spectra and luminescence properties of the Ru(II) species and subunits are dominated by metal-to-ligand charge-transfer (MLCT) transitions and excited states, whereas ligand centered (LC) transitions and excited states govern the spectroscopic and photophysical properties of most of the Ir(III) species here studied, with MLCT states playing an important role when cyclometalated Ir(III) subunits are present. Each metal-based subunit retains in the multinuclear arrays its own spectroscopic properties, but in the case of the mixed Ru-Ir species an efficient, additional decay channel is opened for the excited states involving the Ir-centered subunits, that is, photoinduced energy transfer to the lower-lying MLCT state(s) involving the Ru centers.

Oxidations catalyzed by stable metallo-tetraaryl porphyrins under aqueous-organic two-phase conditions

Oxydation du cyclooctene catalysee par des complexes Mn(III) tetraaryl-5,10,15,20 porphyrines

Asymmetric hydrogen transfer reduction of ketones using chiral perfluorinated diimines and diamines

Abstract Hydrogen transfer reduction of various ketones occurs in a mixture of perfluoroalkane/isopropanol using iridium complexes in association with chiral perfluorinated diimines or diamines as ligands. Enantioselectivity of up to 79% has been obtained. Recycling of the catalyst using chiral perfluorinated diamines as the ligands is possible with no loss of enantioselectivity and very low leaching of iridium in the organic phase.