Phosphine‐Catalyzed Enantioselective (3+2) Annulation of Vinylcyclopropanes with Imines for the Synthesis of Chiral Pyrrolidines

A phosphine‐catalyzed highly enantioselective and diastereoselective (up to 98 % ee and >20 : 1 dr) (3+2) annulation between vinylcyclopropanes and N‐tosylaldimines has been developed, which allows facile access to a range of highly functionalized chiral pyrrolidines. Notably, this method makes use of vinylcyclopropanes as a synthon for phosphine‐mediated asymmetric annulation reaction, which will offer new opportunities for potential applications of cyclopropanes substrates in phosphine‐catalyzed organic transformations. Cyclopropanes are important synthetic building blocks in organic chemistry. In this study, the first phosphine‐catalyzed enantioselective (3+2) annulation between vinylcyclopropanes and N‐tosylaldimines was achieved, which led to the formation of a range of highly functionalized pyrrolidines in high yields with excellent diastereo‐ and enantioselectivities.