Diastereoselective Synthesis of Dibenzo[b,d]azepines by Pd(II)-Catalyzed [5+2] Annulation of o-Arylanilines with Dienes

An efficient method for the construction of dibenzo [b,d]azepines containing two distinct stereogenic elements in a highly diastereoselective fashion is described. The key of the [5 + 2] reaction is to form a pi-allylialladitin species through sequential C-H activation and regiospecific migratory insertion of the diene.This observation contrasts with the behavior of 1,2-alkenes that generally underwent direct alkenylation via beta-hydride elimination.