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 (-)-225 C, (+)- and (-)-223 H (xenovenine), (+)-223 AB, (+)-195 B, and (+)-223 R have been carried out as applications.