Iridium-catalyzed asymmetric [3+2] annulation of aromatic ketimines with alkynes via C-H activation: unexpected inversion of the enantioselectivity induced by protic acids

A cationic iridium/binap catalyst enabled the asymmetric [3+2] annulation of cyclic N-acyl ketimines with internal alkynes via C-H activation to give spiroaminoindene derivatives with high enantioselectivity. The stereochemical course of this annulation was switchable by acid additives.