Asymmetric Synthesis of (−)-Indolizidines 167B and 209D Based on Stereocontrolled Allylation of a Chiral Tricyclic <i>N</i>-Acyl-<i>N,O-</i>acetal

Abstract

[reaction: see text] The tricyclic N-acyl-N,O-acetal incorporating (S)-2-(1-aminoethyl)phenol as a chiral auxiliary underwent TiCl4-mediated allylation to give the chiral (5S)-allylpyrrolidinone with retention of configuration in high yield and diastereoselectivity. On the bases of this methodology, the asymmetric syntheses of the dendrobatid alkaloids (-)-indolizidines 167B and 209D were achieved.