Synthesis and Utilization of 1H-Indazole N-Oxides in the Production of C3-Functionalized 1H-Indazoles

Abstract

AbstractThe medicinal importance, natural rarity, and challenges associated with the synthesis of C3-functionalized 1H-indazoles have propelled the development of novel and practical 1H-indazole N-oxides for the production of diverse arrays of C3-functionalized 1H-indazoles. The use of 1H-indazole N-oxides has been remarkably effective for the selective introduction of diverse functional groups, including amino (NHAr), chloro (Cl), hydroxy (OH), sulfonyl (SO2Ar), aromatic (Ar), olefin, alkyl, and N-formyl (NRCHO) groups, to indazole pharmacophore molecules. This review offers a concise overview of the synthetic approaches and practical applications of 1H-indazole N-oxides, including recent studies conducted by the authors. Transformative reactions involving 1H-indazole N-oxides not only offer strategies for synthesizing C3-functionalized 1H-indazoles but also hold significant potential in medicinal chemistry.1 Introduction2 Synthetic Approaches and Applications of 1H-Indazole N-Oxides3 Summary and Outlook