Stereoselective Synthesis of 3‐Alkylideneoxindoles using Tandem Indium‐Mediated Carbometallation and Palladium‐Catalyzed Cross‐Coupling Reactions

The first efficient methods for the stereoselective synthesis of various (E)‐, (Z)‐, and disubstituted 3‐alkylideneoxindoles via radical cyclization reactions were investigated using tandem indium‐mediated carbometallation and palladium‐catalyzed cross‐coupling reactions. The proper combination of substrates and reaction conditions is important for good yields. The key step is the first stereoselective carboindation reaction using the strong coordination ability of an indium cation to the amide carbonyl oxygen. We applied this method to the synthesis of TMC‐95A precursor. A new N‐debenzylation method with N‐hydroxyphthalimide‐O2‐Co(OAc)2‐Mn(OAc)2 was also developed using a one‐electron oxidation procedure.