Epoxide opening-induced tandem 8-azabicyclo[3.2.1]octane to 6-azabicyclo[3.2.1]octane rearrangement-iminium allylation: synthesis of (+/-)-peduncularine.

An efficient Lewis acid induced nitrogen-driven rearrangement iminium-trapping cascade from an epoxytropinone 3 gives a 7-allylated 6-azabicyclo[3.2.1]octan-3-one 2, which is converted into the alkaloid (+/-)-peduncularine (1).