Advances in Synthesis of Indazole Variants: A Comprehensive Review of Transition Metal, Acid/Base and Green Chemistry-based Catalytic Approaches

Background: Indazole is a heterocyclic motif widely used in medicinal chemistry due to its positive photophysical properties. The development of new methods for synthesizing the indazole scaffold is of great importance in drug discovery. Methods: This study presents a detailed review of current advances in indazole synthesis, focusing on catalyst-based and green chemistry approaches. The analysis is classified based on acid-base and transition-metal catalysts and green chemistry methods. Catalyst-based advances have given a new impetus to the synthesis of this effective pharmacophore. Results: The extensive literature on indazole synthesis demonstrates the notable progress achieved through catalyst-based approaches. These methods have enabled researchers to create a wide range of indazole derivatives and analogs, facilitating their application in pharmaceutical products and organic molecules. The use of acid-base and transition-metal catalysts has been particularly effective in enhancing the efficiency and selectivity of indazole synthesis. Conclusion: Indazoles and their variants are widely used in pharmaceutical products and organic molecules. The recent literature indicates that catalyst-based approaches have resulted in significant advancements in indazole synthesis. This review may be useful for researchers in medicinal chemistry, content chemistry, and agrochemistry.