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 sigma bond of cyclopalladated pyridine derivatives afforded (eta(3)-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. (C) 2003 Elsevier B.V. All rights reserved.