Phosphine‐Catalyzed [3+2] Annulation of N ‐2,2,2‐Trifluoroethylisatin Ketimines with γ‐Substituted Allenoates: Synthesis of Spiro[indoline‐3,2′‐pyrrole]

Synthesis of spiro[indoline‐3,2′‐pyrrole] scaffold compounds from N ‐2,2,2‐trifluoroethylisatin ketimines and γ‐substituted allenoates through a phosphine‐catalyzed [3+2] annulation process has been developed, which could afford an unprecedented access to spirocyclic oxindoles with functionalized CF 3 moiety containing five‐membered rings. The new synthetic protocol used readily available N ‐2,2,2‐trifluoroethylisatin ketimines as the starting materials, inexpensive PPh 3 as the catalyst, and the corresponding products were obtained with yields up to 85 % under mild conditions.