Amphiphilic Immobilized Diphenylprolinol Alkyl Ether Catalyst on PS-PEG Resin

Diphenylprolinol silyl ether is a widely used organocatalyst, and its immobilization on a solid support was investigated for the easy recycling and reuse of this catalyst. Because a silyl ether bond of the catalyst is weak, its alkyl ether was attached to polymers such as a polyquinoxaline-based polymer, a polystyrene polymer (PS) resin, and a polystyrene-poly(ethylene glycol) graft copolymer (PS-PEG) resin. Although a polymer-supported organocatalyst generally decreases its reactivity compared with the monomer catalyst, diphenylprolinol anthryl-methyl ether supported on PS-PEG was found to be a reactive organocatalyst; it catalyzed the Michael reaction of an aldehyde and a nitroalkene in water without an organic solvent being present, with excellent diastereo- and enantioselectivities.

Automated summary

The immobilization of diphenylprolinol silyl ether on solid supports allows for easy recycling and reusability. While polymer-supported organocatalysts generally exhibit decreased reactivity compared to monomer catalysts, diphenylprolinol anthryl-methyl ether supported on PS-PEG resin was found to be a highly reactive organocatalyst, demonstrating excellent diastereo- and enantioselectivities in the Michael reaction of aldehyde and nitroalkene in water without the presence of organic solvents.