Gold‐Catalyzed Formal [4+2] Cycloaddition as Access to Antitumor‐Active Spirocyclic Oxindoles from Alkynes and Isatin‐Derived Ketimines. - Liu, Yaowen; Dietl, Martin C.; Heckershoff, Robin; Han, Chunyu; Shi, Hongwei; Rudolph, Matthias; Rominger, Frank; Caligiuri, Isabella; Asif, Kanwal; Adeel, Muhammad; Scattolin, Thomas; Hashmi, A. Stephen K. (Angewandte Chemie International Edition, 2023)