Enantioselective Syntheses of 2,5-Disubstituted Pyrrolidines Based on Iridium-Catalyzed Allylic Aminations-Total Syntheses of Alkaloids from Amphibian Skins

A broadly applicable route to trans-2,5-disubstituted pyrrolidines has been developed. Key steps are an asymmetric iridium-catalyzed allylic amination, a Suzuki-Miyaura coupling, and an intramolecular aza-Michael addition. Enantiomeric excesses in the range of 93-99% ee have been achieved. Total syntheses of the alkaloids (-)-225C, (+)- and (-)-223H (xenovenine), (+)-223AB, (+)-195B, and (+)-223R have been carried out as applications.