We have reported that copper(I) complexes of the new C1-symmetric pyridine-based 12 membered tetraaza macrocyclic (Pc-L*) ligands are competent catalysts in the enantioselective cyclopropanation of olefins employing ethyl diazoacetate (EDA) as carbene precursor in homogeneous phase[1]. Heterogeneous single site catalysts in many cases show superior performances in terms of activity, selectivity and recyclability coupling together the advantages of heterogeneous and homogeneous systems [2]. Aim of the present work has been to heterogeneize the chiral copper(I) complexes on mesoporous silicas and to test them as catalysts in asymmetric synthesis. Pc-L* Cu(I) complexes were grafted on mesoporous ordered and non-ordered silicas (MCM-41, SBA-15 and Davisil) by the SHB method (Figure).2 SHB (Supported by Hydrogen Bond) is a simple, very mild, rather strong grafting, procedure applicable to a wide range of metal complexes bearing the SO3- moiety as counterion. Materials obtained were fully characterized for metal content, textural properties, hydrogen bonds between Cu(I) complex and surface silanols by a variety of techniques. Catalysts were tested in enantioselective cyclopropanation reactions of olefins. The results will be presented in terms of chemical yields and stereochemical outcome and compared with those obtained in homogeneous phase. The confinement effects, namely the pore size influence as well as the issue of catalyst separation and recyclability were studied and rationalized. [1] Caselli, A.; Cesana, F.; Gallo, E.; Casati, N.; Macchi, P.; Sisti, M.; Celentano, G.; Cenini, S. Dalton Trans. 2008, 4202. [2] C. Bianchini, P. Barbaro, V. Dal Santo, R. Gobetto, A. Meli, W. Oberhauser, R. Psaro, F. Vizza, Adv. Synth. Catal., 2001, 343, 41-45.

ENANTIOSELECTIVE CYCLOPROPANATION REACTIONS CATALYZED BY CU(I) COMPLEXES OF PYRIDINE CONTAINING MACROCYCLIC CHIRAL LIGANDS (PC-L*) SUPPORTED ON SILICAS / A. Caselli, V. Dal Santo, B. Castano, A. Galarneau, E. Gallo, Y. Honemann, R. Psaro. ((Intervento presentato al 24. convegno Congresso Nazionale della Società Chimica Italiana tenutosi a Lecce nel 2011.

ENANTIOSELECTIVE CYCLOPROPANATION REACTIONS CATALYZED BY CU(I) COMPLEXES OF PYRIDINE CONTAINING MACROCYCLIC CHIRAL LIGANDS (PC-L*) SUPPORTED ON SILICAS

A. Caselli
Primo
;
B. Castano;E. Gallo;
2011-09

Abstract

We have reported that copper(I) complexes of the new C1-symmetric pyridine-based 12 membered tetraaza macrocyclic (Pc-L*) ligands are competent catalysts in the enantioselective cyclopropanation of olefins employing ethyl diazoacetate (EDA) as carbene precursor in homogeneous phase[1]. Heterogeneous single site catalysts in many cases show superior performances in terms of activity, selectivity and recyclability coupling together the advantages of heterogeneous and homogeneous systems [2]. Aim of the present work has been to heterogeneize the chiral copper(I) complexes on mesoporous silicas and to test them as catalysts in asymmetric synthesis. Pc-L* Cu(I) complexes were grafted on mesoporous ordered and non-ordered silicas (MCM-41, SBA-15 and Davisil) by the SHB method (Figure).2 SHB (Supported by Hydrogen Bond) is a simple, very mild, rather strong grafting, procedure applicable to a wide range of metal complexes bearing the SO3- moiety as counterion. Materials obtained were fully characterized for metal content, textural properties, hydrogen bonds between Cu(I) complex and surface silanols by a variety of techniques. Catalysts were tested in enantioselective cyclopropanation reactions of olefins. The results will be presented in terms of chemical yields and stereochemical outcome and compared with those obtained in homogeneous phase. The confinement effects, namely the pore size influence as well as the issue of catalyst separation and recyclability were studied and rationalized. [1] Caselli, A.; Cesana, F.; Gallo, E.; Casati, N.; Macchi, P.; Sisti, M.; Celentano, G.; Cenini, S. Dalton Trans. 2008, 4202. [2] C. Bianchini, P. Barbaro, V. Dal Santo, R. Gobetto, A. Meli, W. Oberhauser, R. Psaro, F. Vizza, Adv. Synth. Catal., 2001, 343, 41-45.
Settore CHIM/03 - Chimica Generale e Inorganica
ENANTIOSELECTIVE CYCLOPROPANATION REACTIONS CATALYZED BY CU(I) COMPLEXES OF PYRIDINE CONTAINING MACROCYCLIC CHIRAL LIGANDS (PC-L*) SUPPORTED ON SILICAS / A. Caselli, V. Dal Santo, B. Castano, A. Galarneau, E. Gallo, Y. Honemann, R. Psaro. ((Intervento presentato al 24. convegno Congresso Nazionale della Società Chimica Italiana tenutosi a Lecce nel 2011.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/166074
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