Approaches towards 3-Substituted-3-hydroxyoxindole and Spirooxindole-Pyran Derivatives in a Reaction of Isatin with Acetylacetone in Aqueous Media

The synthetic utility of C-1 and C-3 nucleophilic behavior of acetylacetone in a reaction with isatin for two distinct pharmaceutically relevant scaffolds 3-substituted 3-hydroxyoxindole and spirooxindole-pyran in water is presented. The protocol offers environmentally benign conditions, wide substrate scope, and good to the very good chemical yield of products. The developed methodology has the potential to generate a library of useful synthetic compounds that are of pharmaceutical interest. A plausible mechanism for the formation of products based on the outcome of the reaction is also rationalized.