Intramolecular Mannich reaction in the asymmetric synthesis of polysubstituted piperidines: Concise synthesis of the dendrobate alkaloid (+)-241D and its C-4 epimer

GRAPHICS The intramolecular Mannich reaction of delta -amino beta -keto esters with aldehydes and ketones is a new methodology for the synthesis of polysubstituted piperidines and is illustrated by the concise asymmetric synthesis of the dendrobate alkaloid (+)-241D and its C-4 epimer.