DMSO-catalysed late-stage chlorination of (hetero)arenes

The chlorination of a bioactive compound can change its physiological properties and improve its pharmacokinetic and pharmacological profiles. It therefore has been an important strategy for drug discovery and development. However, the direct aromatic chlorination of complex bioactive molecules is too difficult to be practical. In fact, many functional groups such as hydroxyls, amines, amides or carboxylic acids may strongly restrain the reactivity of Cl+ by forming a halogen bond. Here we report a highly efficient aromatic chlorination of arenes that is catalysed by dimethyl sulfoxide with N-chlorosuccinimide as the chloro source. The mild conditions, easy-availability and stability of the catalyst and reagents, as well as good functional-group tolerance, showed the approach to be a versatile protocol for the late-stage aromatic chlorination of complex natural products, drugs and peptides. The multi-gram experiment and low-cost of N-chlorosuccinimide and dimethyl sulfoxide shows great potential for drug discovery and development in industrial applications. Late-stage aromatic chlorination of active pharmaceutical ingredients has enormous potential in drug discovery yet still features limited applicability due to issues of functional-group tolerance. Now, dimethyl sulfoxide is reported as catalyst for the chlorination of a diverse family of bioactive molecules in combination with N-chlorosuccinimide.