Metal‐Catalyzed Synthesis of Benzofused Five‐Membered N/O/S Heterocycles, a Progressive Area in Synthetic Chemistry

Abstract Benzo‐fused five‐membered N/O/S heterocyclic compounds, such as indole, benzofuran, and benzothiophene, possessing a single heteroatom, have important applications in medicinal chemistry, agrochemistry, and material chemistry. Metal‐catalysed reactions are well‐established synthetic pathways for the formation of C−X bonds, enabling the direct synthesis of heterocycles. This approach offers advantages over traditional methods, such as fewer steps, increased atom economy, low catalyst loading, regioselectivity, and stereoselectivity. Due to their widespread use in the pharmaceutical industry, the formation of C−N, C−O, and C−S bonds has gained significant attention. This article focusses on the metal‐catalysed synthesis and corresponding mechanistic approaches for N/O/S‐heterocycles, particularly indole, benzofuran, and benzothiophene, reviewing the progress of the past five years and discussing unexplored future opportunities.