Amphiphilic Immobilized Diphenylprolinol Alkyl Ether Catalyst on PS-PEG Resin
Seitaro Koshino, Shusuke Hattori, Shota Hasegawa, Naoki Haraguchi, Takeshi Yamamoto, Michinori Suginome, Yasuhiro Uozumi, Yujiro Hayashi
Abstract
Abstract 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 anthrylmethyl 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.