L-Proline Functionalized Polymers as Supported Organocatalysts

摘要

The use of small organic molecules as alternative catalysts to metal- and biocatalysts in asymmetric reactions has gathered much attention in recent years. The amino acid L-proline has been named the 'simple enzyme' as it is proposed to mimic the mechanistic properties of Nature's aldolase enzymes. Thus, it has been well studied and is today one of the most popular organocatalysts in asymmetric synthesis. More recently, a great deal of research has been focused on the immobilization of L-proline on solid supports to enhance catalytic activity as well as to facilitate the reuse of the catalyst. We herein report the synthesis of well-defined L-proline functionalized polystyrene copolymers using RAFT polymerization techniques, for use in supported catalysis. As a result of the non- random distribution of the L-proline units in the polystyrene backbone, solution self-assembly into higher ordered structures was observed. The effects of these assemblies as potential nanoreactors to enhance the activity and selectivity of selected asymmetric organic reactions are explored in this work.