Polymer-Supported Chiral Lewis Base Catalysts

asymmetric addition - allylation - Lewis bases - polymer effect

Significance

Novel polymer-supported chiral phosphoramides were used as a Lewis base catalyst 1 in the asymmetric addition of allyltrichlorosilane to benzaldehyde. The allylation of benzaldehyde proceeded in the presence of the catalyst 1 (10 mol% of phosphoramide unit) at -78 °C for six hours in dichloromethane to give 1-phenyl-but-3-en-1-ol in up to 84% yield with enantiomeric excesses of 63%. The reaction was accelerated by the addition of five equivalents of ethyldiisopropyl­amine. Catalyst 1 was found to be more effective its homogeneous counterpart.

Comment

This is the first report on the synthesis of polymers having chiral phosphoramides and their catalytic applications in asymmetric addition of allyltrichlorosilane to benzaldehyde.