Au-catalyzed stereodivergent synthesis of 2,5-disubstituted pyrrolidines: total synthesis of (+)-monomorine I and (+)-indolizidine 195B.

Stereodivergent synthesis of 2,5-disubstituted pyrrolidines was achieved via a Au-catalyzed tandem intramolecular alkyne hydroamination/iminium formation/Et 3 SiH reduction. Importantly, the stereochemical outcome could be switched by choosing an appropriate nitrogen protecting group. Total synthesis of a diastereomeric pair of alkaloid natural products, monomorine I and indolizidine 195B, was achieved to showcase the synthetic utility of the tandem reaction.