Transformable/modifiable directing group-assisted C(sp 2 )–H functionalizations

Directing groups have been widely used for transition metal-catalyzed regioselective C-H functionalizations. The heteroatoms in the directing group coordinate with the metal catalyst and activate relatively inert C-H bonds. However, after the desired C-H functionalization, the directing groups may not always be necessary, so their removal demands extra synthetic steps. This limitation can be overcome by employing a directing group that can be transformed into another valuable functionality in one pot or can be easily modified post C-H functionalization. In this review, we shall discuss the recent developments in such transformable/modifiable directing groups that afford complex organic scaffolds through C(sp²)-H activation-initiated one-pot and step-economical synthesis.