Electrophilic halogenation of aromatics and heteroaromatics with N-halosuccinimides in a solid/liquid system using an H+ ion exchanger or ultrasonic irradiation

The halogenation of thiophene, its methyl and halo derivatives as well as activated arenes (mesitylene, 1,3-dimethoxybenzene, 2,3-dimethylanisole) in a two-phase hexane/solid N-halosuccinimide system is catalysed by the strongly acidic sulfonated resin Amberlyst® 15. These reactions proceed readily at room temperature and give the ring-halogenated products in good yield. An alternative approach utilizes ultrasonic irradiation in the absence of acid. The weakly acid carboxylic resin Amberlite® IRP-64 catalyzes the bromination of furan with NBS in pentane, or in the absence of additional solvent.