Trihaloisocyanuric Acids: Useful Reagents for Halogenation Reactions and Heterocyclic Scaffold Construction

Trihaloisocyanuric acids [1,3,5-trihalo-1,3,5-triazine-2,4,6-(1H,3H,5H)-triones] are commercially available or easily prepared solids. They are highly reactive, stable, easily handled, and have an excellent atom economy, transferring up to three halogen atoms to organic substrates. In these regards, the present review summarizes their synthetic applications as safe and convenient reagents. Therefore, electrophilic halogenation reactions of alkenes, alkynes, arenes, heteroarenes, carbonyl compounds, and heteroatoms, as well as radical halogenation involving saturated substrates and in situ halogenated intermediates for Appel-type reactions are presented and discussed. Remarkably, applications of trihaloisocyanuric acids in processes for the construction of heteroarene scaffolds based on electrophilic halo- and oxidative cyclization, multicomponent reactions, and telescopic reactions are also given.