Organocatalytic Halogenation of Aromatic and Heteroaromatic Compounds

The halogenation of aromatic and heteroaromatic systems has attracted considerable attention in recent decades owing to the importance of haloaromatics in biologically relevant compounds and their role as essential building blocks for more complex systems. In recent years, various research groups have explored the challenge of developing new synthetic methodologies for electrophilic halogenation. Nevertheless, these methods continue to encounter several challenges, such as waste products from halogenating agents, toxic or contaminating reagents, and problems with low regioselectivity, with polyhalogenation—often the predominant side reaction—occurring in some cases. In this context, organocatalysis has emerged as a promising approach to address these limitations. This review highlights key organocatalytic strategies reported in the last 14 years and discusses experimental aspects, mechanisms, and selectivity issues in chlorination, bromination, fluorination, and iodination of aromatic systems.