Studies toward the Synthesis of (+)-Palustrine: The First Asymmetric Synthesis of (-)-Methyl Palustramate.

The stereoselective synthesis of (-)-methyl palustramate, a possible intermediate for the synthesis of (+)-palustrine, is described. The key step of the synthesis is a conformationally restricted Claisen rearrangement to afford the highly functionalized 1-benzylpipecolic ester 10. In addition, a new procedure for debenzylation of 1-benzylpiperidines (Li, (NH(2)CH(2))(2), Et(3)N, THF) was used to remove the benzyl protecting group where traditional methods failed.