Directing group migration strategy in transition-metal-catalysed direct C-H functionalization.

Very recently, directing group (DG) migration has emerged as a practical strategy for transition-metal-catalysed direct C–H activation, resulting in a highly atom-economical process and enabling the reusage of DG. Therefore, great progress has been made in developing multitasking DGs. In this tutorial review, we present the rapid advances of this novel strategy by analyzing and comparing the different types of migratable DGs (including N–O, N–C, N–N or O–C bond cleavage to trigger DG migration). The related mechanisms, as well as synthetic applications, are also mentioned.