Palladium-mediated intramolecular C–N bond formation involving allyl substituted pyridines. Application to a novel strategy for the synthesis of the skeleton of berberinium derivatives

The insertion of allenes in the Pd–C σ bond of cyclopalladated pyridine derivatives afforded (η3-allyl) Pd complexes. The ideally located imine unit reacted selectively with the allyl functionality to yield a series of new cationic heterocycles. The process opened the route to a novel strategy for the synthesis of berberiniums, a class of molecules of pharmacological interest.