Polytopic bis(oxazoline)-based ligands for the development of recoverable catalytic systems applied to the cyclopropanation reaction

New ditopic and tetratopic chiral ligands, based on the bis(oxazoline) moiety, have been synthesized and their copper complexes tested as catalysts in the benchmark asymmetric cyclopropanation reaction of styrene with ethyl diazoacetate. The polytopic nature of these ligands enables a release-capture strategy to efficiently recycle the enantioselective catalyst by precipitation of a coordination polymer at the end of the reaction. This strategy enables the self-supported catalyst to be reused up to 20 times leading to good yields and enantioselectivities.Financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) (project number CTQ2011-28124-C02-01), the European Social Fund (ESF) and the Gobierno de Aragón (Grupo Consolidado E11) is gratefully acknowledged. ACM is indebted to the Consejo Superior de Investigaciones Científicas for a grant (CSIC JAE-Pre program).Peer Reviewe