Enantioselective Construction of Spirooxindole‐γ‐butyrolactones via NHC‐Bound Isobenzofulvene [10π+2π] Cycloaddition

Comprehensive Summary We report an N ‐heterocyclic carbene (NHC)‐catalyzed [10π+2π] cycloaddition between indene‐2‐carbaldehydes and isatins, delivering spirooxindole‐γ‐butyrolactones with moderate yields (up to 68%) and excellent enantioselectivity (up to 93% ee). This transformation proceeds via NHC‐bound isobenzofulvene intermediates and represents the first successful application of all‐carbon higherene in NHC‐catalyzed [10π+2π] cycloadditions.