Allylsilanes. Synthesis of enantiopure heterocycles

Abstract

Chiral, non-racemic bicyclic lactams have been shown to undergo stereoselective processes from which diastereomerically pure products were obtained. The application of allylsilane additions to the bicyclic lactam have been investigated. The annulation reaction employing allyldimethyltritylsilane has offered access to cyclobutane-fused pyrrolidines which lead to the examination of other addition reactions. Subsequently, the Sakurai reaction was examined and a heretofore unseen steric effect was discovered involving the addition of allyltrimethylsilane to α,β-unsaturated bicyclic lactams. Following this study, the addition of allyltrimethylsilane to the N,O-acetal of the [3.3.0]bicyclic lactam was explored and lead to an efficient method for the construction of indolizidines (including (+)-coniceine) and the key precursor to Danishefsky's synthesis of indolizomycin.