Stereoselective Synthesis of Enantiomerically Pure Nupharamine Alkaloids from Castoreum

An animalic note : The first total synthesis of the all‐ cis nupharamine 2 , an alkaloid from beaver castoreum, is based on the stereoselective domino Mannich–Michael reaction of N ‐galactosylfurylaldimine to give 1 (Piv=pivaloyl), subsequent conjugate cuprate addition, and stereoselective protonation of the enolate. These reactions are all controlled by the carbohydrate. Protonation of the enolate after cleavage of the auxiliary leads to epimer 3 .