Recent Advances in First‐Row Transition‐Metal‐Mediated C−H Halogenation of (Hetero)arenes and Alkanes

AbstractThe ubiquity of carbon halogen bonds in the structural core of numerous biomolecules and pharmaceuticals along with their role as synthetic precursors in various organic reactions makes the organic halides a crucial class of organic compounds. Consequently, the synthesis of organic halides with high regioselectivity is of paramount importance in synthetic chemistry. In nature, selective halogenation is achieved by metalloenzymes with high efficiency involving high‐valent iron‐oxo as active species. The high selectivity of halogenating enzymes attracted considerable attention leading to the development of several biomimetic approaches for C−H halogenation. Moreover, the emergence of transition metal (TM) catalyzed site‐selective C−H halogenation protocols through the development of several directed strategies has also been impressive. There has been significant development in the first row TM catalyzed C−H halogenation reactions despite the dominance of late transition metals catalysts in this field. But in literature, there is no up‐to‐date recent review article that consolidates bio‐mimetic as well as synthetic strategies of C−H halogenation (X=Cl, Br, I) containing organo‐fluorination with all the first‐row transition metals. Thus, we got motivated and have focused to elucidate the recent developments of first row TM‐catalyzed C−H halogenation of (hetero)arenes and alkanes through bio‐mimetic approaches as well as directed and undirected strategies in this present review. Additionally, this review covers the recent progresses in the C−H fluorination methodologies. Altogether, the review will provide a combined overview of all the strategies of first‐row transition‐metal‐mediated C−H halogenation reactions that may benefit the scientific community towards the development of new methodologies in this field.