Polystyrene grafted with a chiral zinc-complexing camphor-derived N,N-disubstituted hydroxyamide is proposed as a new type of functional polymer of high reusability for the development of sustainable organozinc-catalyzed asymmetric reactions. The main goal of this new functional polymer is the ease of the hydroxyamide-moiety preparation (cheap chiral ligand obtained straightforwardly from an enantiopure starting material coming from the chiral pool), as well as its chemical robustness when compared with other related zinc-complexing functional groups. The latter allows the polymer to be active after multiple applications, without significant loss of its catalytic activity. This fact is exemplified by the design and preparation of a polymer functionalized with a bis(hydroxyamide) proved previously as active in the homogeneous enantioselective addition of diethylzinc to aldehydes. The result is a cheap functional polymer with a very high reusability (the enantioselectivity and chemical yield are maintained practically constant after 20 applications). Additionally, a methodology for the multicycle use of these functional polymers is presented.
Copyright © 2012 Wiley Periodicals, Inc., A Wiley Company.