Organocatalytic entry into 2,6-disubstituted aza-Achmatowicz piperidinones: application to (-)-sedacryptine and its epimer.

Enantiomerically pure 2,6-disubstituted piperidinones were synthesized from furfural involving an organocatalyzed Mannich reaction, aza-Achmatowicz reaction, and an N-acyliminium ion-mediated coupling step. This approach was also successfully applied to a total synthesis of (-)-sedacryptine and one of its epimers.