Micelles assembled from amphiphilic molecules have proved to be ideal scaffolds to construct artificial catalysts mimicking enzymatic catalytic behavior. In this paper, we describe the synthesis of amphiphilic poly(2-oxazoline) derivatives with l-prolinamide units in the side chain and their application in asymmetric aldol reactions. Upon dissolution in water, the pseudopeptide polymers self-assembled into particles with different sizes, relying on the copolymer composition and distribution of hydrophilic/hydrophobic segments in the polymer chain. A preliminary study has demonstrated that the catalytic activity of these polymeric organocatalysts are strongly dependent on the aggregated architecture. The micelle-type assemblies can act as nanoreactors to efficiently promote the direct aldolisation of cyclohexanone with aromatic aldehydes in aqueous media, affording anti-aldol products in excellent yields (88⁻99%) and higher stereoselectivities (90/10 dr, 86% ee) compared to their nonmicellar systems under identical conditions.
Keywords: asymmetric aldol reaction; micelle; organocatalysis; poly(2-oxazoline); pseudopeptide.