Total Synthesis of (-)-Leuconicine A and B

Concise asymmetric total syntheses of Strychnos alkaloids (-)-leuconicine A (14 steps, 9% overall yield) and B (13 steps, 10% overall yield) have been accomplished. Key steps include (1) our sequential one-pot spiro-cyclization/intramolecular aza-Baylis-Hillman method to prepare the ABCE framework; (2) a novel domino acylation/Knoevenagel cyclization to prepare the F-ring; and (3) a Heck cyclization to access the D-ring.