Highly Diastereo‐ and Enantioselective NHC‐Catalyzed [3 + 2] Annulation of Enals and Isatins.

A series of spirocyclic lactones (III) is prepared with good diastereo- and enantioselectivities by reaction of isatins (I) with enals (II) in the presence of a chiral N-heterocyclic carbene.