Immobilization of catalysts derived from Cinchona alkaloids on modified poly(ethylene glycol)

✍ Scribed by Tamara Danelli; Rita Annunziata; Maurizio Benaglia; Mauro Cinquini; Franco Cozzi; Graziella Tocco

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 206 KB
• Volume: 14
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/s0957-4166(02)00830-3

✦ Synopsis

The straightforward immobilization of some derivatives of Cinchona alkaloids on modified poly(ethylene glycol)s is reported. The compounds, obtained by simple reactions exploiting different sites for the attachment of the alkaloids to the polymer, were tested as catalysts in the enantioselective benzylation of the benzophenone imine of glycine t-butyl ester (ee up to 64%) and in the conjugate addition of thiophenol to cyclohexenone (ee 22%). The observed stereoselectivities were compared to those obtained either with the unsupported catalysts or with the catalysts immobilized on different polymeric matrixes. The influence of the poly(ethylene glycol) moieties on the catalytic activity is discussed.