We have recently reported that copper(I) complexes of the new C1-symmetric pyridine-based 12-membered tetraaza macrocycles, Pyridine Containing Ligands (Pc-L*), are competent catalysts in asymmetric cyclopropanations.1 Herein we report the synthesis of new C1- and C2-symmetric Pc-L* macrocycles and the use of their Cu(I) complexes as catalysts for the title reaction. The synthetic path is very simple and it takes advantage of commercially available, enantiomerically pure, chiral amino-alcohols and/or primary amines. Compounds 1a-b have been obtained in a quantitative yield employing naturally occurring L-valinol as starting material.2 Differently substituted macrocyclic ligands 4a-d have been obtained in moderate to good yields (20-70%) and they have been fully characterized including elemental analysis, MS, 1H-NMR, 13C-NMR. The Cu(I) complexes of those ligands have been isolated and characterized, and they showed good catalytic activities in the cyclopropanation of differently substituted olefins employing ethyl diazoacetate (EDA) as carbene precursor. In all cases a complete conversion of EDA was observed and, depending on the employed ligand, cyclopropanes have been obtained with tunable cis/trans stereoselectivities and e.e. up to 96%. Moreover, the obtained results allow a direct comparison of the reaction stereoselective outcome between C1- and C2-symmetric ligands having the same molecular structure.

Modular approach to chiral pyridine-containing macrocyclic ligands (Pc-L*) : application of their Copper(I) complexes in asymmetric cyclopropanations / B. Castano, T. Pedrazzini, E. Gallo, A. Caselli. ((Intervento presentato al 25. convegno International Conference on Organometallic Chemistry (ICOMC) tenutosi a Lisbon nel 2012.

Modular approach to chiral pyridine-containing macrocyclic ligands (Pc-L*) : application of their Copper(I) complexes in asymmetric cyclopropanations

B. Castano
Primo
;
T. Pedrazzini;E. Gallo;A. Caselli
2012-09-05

Abstract

We have recently reported that copper(I) complexes of the new C1-symmetric pyridine-based 12-membered tetraaza macrocycles, Pyridine Containing Ligands (Pc-L*), are competent catalysts in asymmetric cyclopropanations.1 Herein we report the synthesis of new C1- and C2-symmetric Pc-L* macrocycles and the use of their Cu(I) complexes as catalysts for the title reaction. The synthetic path is very simple and it takes advantage of commercially available, enantiomerically pure, chiral amino-alcohols and/or primary amines. Compounds 1a-b have been obtained in a quantitative yield employing naturally occurring L-valinol as starting material.2 Differently substituted macrocyclic ligands 4a-d have been obtained in moderate to good yields (20-70%) and they have been fully characterized including elemental analysis, MS, 1H-NMR, 13C-NMR. The Cu(I) complexes of those ligands have been isolated and characterized, and they showed good catalytic activities in the cyclopropanation of differently substituted olefins employing ethyl diazoacetate (EDA) as carbene precursor. In all cases a complete conversion of EDA was observed and, depending on the employed ligand, cyclopropanes have been obtained with tunable cis/trans stereoselectivities and e.e. up to 96%. Moreover, the obtained results allow a direct comparison of the reaction stereoselective outcome between C1- and C2-symmetric ligands having the same molecular structure.
Settore CHIM/03 - Chimica Generale e Inorganica
http://cqe.ist.utl.pt/events/icomc25/
Modular approach to chiral pyridine-containing macrocyclic ligands (Pc-L*) : application of their Copper(I) complexes in asymmetric cyclopropanations / B. Castano, T. Pedrazzini, E. Gallo, A. Caselli. ((Intervento presentato al 25. convegno International Conference on Organometallic Chemistry (ICOMC) tenutosi a Lisbon nel 2012.
Conference Object
File in questo prodotto:
File Dimensione Formato  
ICOMC0001.pdf

accesso aperto

Descrizione: Abstract per gli atti del congresso
Tipologia: Post-print, accepted manuscript ecc. (versione accettata dall'editore)
Dimensione 3.97 MB
Formato Adobe PDF
3.97 MB Adobe PDF Visualizza/Apri
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/387317
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact