Asymmetric Total Synthesis of Vincadifformine Enabled by a Thiourea-Phosphonium Salt Catalyzed Mannich-Type Reaction.

An asymmetric total synthesis of vincadifformine is described. The limited tactics with chiral cation-directed catalysis in total synthesis inspired the development of our strategy for accessing this alkaloid in enantionrich form. The route features a thiourea-phosphonium salt catalyzed Mannich-type reaction, a phosphine-promoted aza-Morita-Baylis-Hillman reaction and a trifluoroacetic acid promoted deprotection/amidation cascade process.