Synthesis of Polymer-supported Chiral Lithium Amide Bases and Application in Asymmetric Deprotonation of Prochiral Cyclic Ketones

Polymer-supported chiral amines were effectively prepared from amino acid derivatives and Merrifield resin. Treatment of polymer-supported amines with n-butyllithium gave the corresponding polymer-suppported chiral lithium amide bases, which were tested in the asymmetric deprotonation reactions of prochiral ketones. The trimethylsilyl enol ethers were obtained in up to 82% ee at room temperature. The polymer-supported chiral lithium amides can be readily recycled and reused without any significant loss of reactivity or selectivity.