Rapid Assembly of Quinolizidines via Consecutive Nucleophilic Cyclizations onto Activated Amides

A new approach to the synthesis of quinolizidines involving a cascade of nucleophilic cyclizations triggered by chemoselective amide activation is reported. Particular attention was given to the effect of the nature of the tethered nucleophiles on the cascade of cyclizations. As a result, simple acyclic amides gave rapid access to functionalized quinolizidines bearing either a tertiary or quaternary center at the ring junction. Such a fused bicyclic motif is found in several alkaloids.