Aconitine synthesis studies. A modeling construction of the functionalized BCDE tetracyclic ring system

Abstract

The first model synthesis of the fully functionalized BCDE tetracyclic analogue 2 of aconitine has been accomplished. A tricyclic intermediate was prepared through highly stereospecific reduction of the ketone intermediates 14 and 16 as well as the following facile Wagner–Meerwein rearrangement. A stereoselective Michael addition and reductive cyclization involving a sequential nitrile hydration and silane promoted reduction were exploited to construct the nitrogen containing six-membered E ring bearing vicinal tertiary and quaternary centers.