Formal synthesis of the bisbenzylisoquinoline alkaloid berbamunine by asymmetric substitution of chiral organolithium compounds.

Asymmetric alkylation of enantiomeric tetrahydroisoquinolyl oxazolines was achieved with 96-97% diastereoselectivity. Removal of the oxazoline chiral auxiliary and further transformations provide a straightforward synthesis of the two synthetic intermediates that were previously synthesized by resolution, and which comprise a formal synthesis of berbamunine by Ullman coupling.