Supported heteropolyanions as solid counterions for the electrostatic immobilization of chiral copper complexes

Abstract

8 páginas, 7 figuras, 4 tablas.-- et al.Supported (PW12O3_40)) is a suitable counterion to immobilize chiral azabis(oxazoline)–copper complexes through electrostatic interactions (ion pair formation). Catalytic results are good to excellent in cyclopropanation reactions (up to 97% ee). Partial leaching during recycling when mono-exchanged species are present, favored by strong coordination of by-products, can be minimized by a proper solvent choice and by optimization of the recycling system, allowing the recovery and reuse of the catalyst at least six times without loss of activity and enantioselectivities in the range of 82–96% ee for trans-cyclopropanes.This work was made possible thanks to the generous financial support of the Spanish Ministerio de Ciencia e Innovación (projects CTQ2008-05138 and Consolider Ingenio 2010 CSD2006-0003), the Diputación General de Aragón (E11 Group co-financed by the European Regional Development Funds), and the Agencia Española de Cooperación Internacional (project A/5392/06).Peer reviewe