Convergency and divergency as strategic elements in total synthesis:: The total synthesis of (-)-drupacine and the formal total synthesis of (±)-Cephalotaxine, (-)-cephalotaxine, and (+)-cephalotaxine

[GRAPHICS] A concise route toward the syntheses of (-)-drupacine and (+)- and (-)-cephalotaxine has been developed. The syntheses rely on Pd(II)-catalyzed aerobic oxidative heterocyclization chemistry, which was employed to rapidly construct an important spirocyclic amine intermediate. A dynamic beta-elimination/conjugate addition process was strategically applied to complete the first asymmetric total synthesis of (-)-drupacine.