Abstract
exo
-Metallacycles have become the key reaction intermediates in activating various remote C(sp
2
)–H and C(sp
3
)–H bonds in the past decade and aided in achieving unusual site-selectivity. Various novel
exo
-chelating auxiliaries have assisted metals to reach desired remote C–H bonds of different alcohol and amine-derived substrates. As a result, a wide range of organic transformations of C–H bonds like halogenation, acetoxylation, amidation, sulfonylation, olefination, acylation, arylation,
etc.
were accessible using the
exo
-metallacycle strategy. In this review, we have summarized the developments in C–H bond activation
via
four-, five-, six-, seven- and eight-membered
exo
-metallacycles and the key reaction intermediates, including the mechanistic aspects, are discussed concisely.