Rapid construction of the unique BCD ring system of tricyclo[6.2.1.0]undecane in the C19-diterpenoid alkaloid aconitine

A model study leading to the preparation of the unique tricyclo[6.2.1.0]undecane BCD ring systems of aconitine is described. The synthesis features an unprecedented diastereoselective oxidative dearomatization/dimerization/retro-DA/IMDA cascade reaction and a highly efficient Wagner-Meerwein rearrangement.