Divergent and Selective Synthesis of 3-Alkylidene Oxindoles Using Pd-Catalyzed Multicomponent Reaction

Abstract

Herein, a divergent and selective synthesis of (E)-3-alkylidene oxindole, which is a highly valuable framework due to its presence in biologically important molecules, via palladium-catalyzed multicomponent reaction of 3-diazo oxindole, isocyanide, and aniline has been developed. Further, the feasibility of the reaction was demonstrated by employing differently substituted 3-diazo oxindoles, isocyanides, and anilines as starting material and obtaining the corresponding products in 31-83% isolated yields. Besides, a plausible mechanism has been presented and further investigated using DFT calculations which suggest the formation of the Pd-carbene complex and ketenimine intermediate as the key step during the catalytic cycle.