First Recoverable and reusable enantioselective catalytic system for the Kharasch-Sosnovsky allylic oxidation of alkenes, based on a ditopic azabisoxazoline ligand

摘要

The allylic oxidation of alkenes with a stoichiometric amount of tert-butyl peroxybenzoate, in the presence of a catalytic amount of Cu(I) (Kharasch-Sosnovsky oxidation) is an interesting catalytic organic transformation. The enantioselective version of this reaction, catalyzed by chiral copper complexes, is a relatively recent contribution.1 Good enantioselectivities (in the range 60-80% ee) have been obtained with different chiral ligands. In some cases, over 90% ee values have been described using chiral bis(oxazoline), Pybox or bipyridine ligands. However, one of the questions still unresolved is that of the preparation of recoverable and reusable efficient catalytic systems for this reaction.