Pyrrolidine and Indolizidine Alkaloids from Chiral N-tert-Butanesulfinyl Imines Derived from 4-Halobutanal

Abstract

An efficient stereocontrolled preparation of 2-substituted pyrrolidines and 5-substituted indolizidin-7-ones, by using chiral N-tert-butanesulfinyl imines derived from 4-halobutanal as starting materials, is detailed. Addition of Grignard reagents and a decarboxylative Mannich­ reaction with β-keto acids involving these chiral imines proceeded with high diastereoselectivity. The synthesis of the pyrrolidinic alkaloids (–)-bgugaine, (+)-villatamine B, (–)-norhygrine, trans-dendrochrysanine, and (–)-ruspolinone demonstrated the utility of this methodology.