A Formal Condensation and [4+1] Annulation Reaction of 3‐Isothiocyanato Oxindoles with Aza‐o‐Quinone Methides

A formal condensation and [4+1] annulation reactions of 3‐isothiocyanato oxindoles with aza‐ o ‐quinone methides have been reported in this paper for the first time. The use of Na 2 CO 3 as a base exclusively gave the corresponding condensed products in good yields, which can be smoothly transformed into the formal [4+1] annulation products if using DBU as a base. In addition, isothiocyanate could serve as a leaving group during the nucleophilic addition reaction has been disclosed. The two bases play different roles in the reaction and the desired cyclized products can be also obtained in good to high yields in a one‐pot manner under mild conditions. magnified image