Recent advances in Ugi reaction and its post-transformation strategies for crafting diverse indole frameworks

Indoles and their fused analogues are ubiquitous structural scaffolds present in a plethora of bioactive natural products and pharmaceutical compounds, showcasing their importance in drug design and delivery. Since the discovery of isocyanide-based multicomponent reactions (IMCRs), especially the Ugi reaction, there has been exponential growth in the development of new methodologies based on the post-modification of the Ugi reaction. This has led to the creation of diverse heterocyclic scaffolds, macromolecules, and natural products. This review summarizes the progression of Ugi-multicomponent reactions (MCRs) and their post-modification methods from 2012 to mid-2024. It highlights the documented protocols for constructing various indoles and hetero-fused indole derivatives in an enantioselective, regioselective, and chemoselective manner, emphasising their significance for medicinal chemists.