Experimental and Computational insight into Transition Metal Catalyzed Cascade Reactions

Abstract

Great efforts have been devoted in the past many years to synthesizing clinically important novel heterocyclic compounds using transition metal-mediated reactions. Further, transition metal-catalyzed cascade or tandem reactions for the synthesis of crucial heterocyclic scaffolds have attracted a lot of attention in the last few years. These reactions can form multiple bonds in one pot without changing the reaction conditions and overall reduce the reaction steps and requirement of intermediate purifications. The reduction of reaction steps leads to saving reagents, energy and eliminates waste generation which makes the cascade reactions eco-friendly as well as highly economical. In this context, several transition metal catalysts like Rh, Pd, Cu, Ru, Ir, Fe, etc. have been employed to perform these kinds of reactions. In this view, carbenes or their precursors like diazo, hydrazones, etc. played an important role in making them more advantageous. On the other hand, computational chemistry is playing an important role and growing its roots in various fields of chemistry day by day. Particularly, in organic synthesis, DFT studies are widely used for mechanistic investigation and treated as an important tool for novel synthesis route detection. In the first chapter of this thesis, we are highlighting some appreciable efforts made in recent years towards the synthesis of highly important novel heterocyclic moieties by using palladium catalyzed cascade reactions including carbene transfer, isocyanide insertion, C-H activation, and cyclization as the vital steps. Also, mechanistic investigation via various experimental and computational studies, further transformation and applications, etc. are covered in these reports. In the second chapter, we have described a divergent and selective synthesis of (E)-3-alkylidene oxindole, which is a highly valuable framework due to its presence in the biologically important molecules, via palladium-catalyzed multicomponent reaction of 3-diazo oxindole, isocyanide, and aniline has