Total Synthesis of Mersicarpine through a Cationic Cyclization Approach

A concise total synthesis of mersicarpine is achieved by exploiting a cyclic carbamate for generation of a tertiary carbocation. The key step involves intramolecular Friedel–Crafts alkylation with this carbocation for the construction of a quaternary carbon center and a subsequent oxidation and cyclization cascade for the formation of a seven-membered cyclic imine. The chemistry allowed for a rapid one-pot synthesis of mersicarpine from a simple intermediate using straightforward chemical operations.