A Pseudopeptide Polymer Micelle Used for Asymmetric Catalysis of the Aldol Reaction in Water

Abstract

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.

Thermo‐responsive block copolymer micelle‐supported (S)‐α,α‐diphenylprolinol trimethylsilyl ether for asymmetric Michael addition of nitroalkenes and aldehydes in water

“…We found that the solvent had significant effect on this reaction, and the use of H 2 O as solvent, the reaction of trans ‐ β ‐nitrostyrene and propanal rendered the best results with high yield (80%) and enantioselectivity (95%) of corresponding adduct in the presence of 1 mol% micellar catalyst and 5 mol% benzoic acid (PhCOOH) additive at room temperature for 24 h (Table 1, Entry 5). This result might be ascribed to the good difussion of the micellar catalyst in water compared to other organic solvents 31 . In addition, the temperature was also a key factor.…”

Micellar Nanoreactors from Amphiphilic Copolymers for Thia-Michael Addition in Water

“…Nanoreactor is one of the most promising applications of polymeric micelles. 14,15 There are also reports on the use of polymeric micelles as nanocatalysts for organic reactions that can be done under mild conditions. 16 It holds many beneficial properties regarding structural variability, stability, functionality, and ability to carry out reactions under mild conditions.…”

“…These obstacles can be mitigated by using micellar systems such as surfactants − or polymeric micelles , of which hydrophobic pockets can encapsulate and stabilize organic substrates in water and thus act as nanoreactors for organic synthesis. Nanoreactor is one of the most promising applications of polymeric micelles. , There are also reports on the use of polymeric micelles as nanocatalysts for organic reactions that can be done under mild conditions . It holds many beneficial properties regarding structural variability, stability, functionality, and ability to carry out reactions under mild conditions. − For example, O’Reilly and co-workers installed 4-(dimethylamino)­pyridine (DMAP) moieties to the hydrophobic core of polymeric micelles that catalyzed acylation reactions in water .…”

Synthesis of block copolymers containing 3-chloro-2-hydroxypropyl methacrylate by NMP – a versatile platform for functionalization

“…26 In case of nanoreactors based on amphiphilic block copolymers a concise number of literature-known examples are available dealing with covalently bound organocatalysts. [27][28][29][30][31][32] A straightforward approach towards such systems is given by providing suitable ligand moieties for metal complexation directly attached to the polymer backbone. 19,[33][34][35][36][37][38][39] In this work we investigate the suitability of 3-chloro-2-hydroxypropyl methacrylate (ClHPMA) as platform to introduce ligand moieties within nanostructured soft matter.…”