Advances in the catalyst- And reagent-controlled site-divergent intermolecular functionalization of C(sp3)–H bonds

Abstract

Intermolecular C(sp3)–H bond functionalization reactions promise to revolutionize how we synthesize organic molecules by enabling the introduction of functionality at previously inert sites. However, one of the greatest challenges in this research field is site-selectivity, wherein chosen C(sp3)–H bonds must be selectively functionalized and other C(sp3)–H bonds with similar stereoelectronic properties must remain intact. To address this problem, chemists have developed methods that rely on targeting innately more reactive C(sp3)–H bonds or on using pre-installed functional groups to direct a catalyst or reagent to a particular C(sp3)–H bond. However, such approaches invariably have limited applicability because only a handful of innately reactive C(sp3)–H bonds or those nearby certain functional groups can be functionalized with good site-selectivity. To overcome these limitations, chemists also have developed catalysts and reagents that control the site of C(sp3)–H bond functionalization and have begun to unlock the potential of these reactions to achieve the site-divergent functionalization of C(sp3)–H bonds, wherein the site of functionalization is changed by modulating the stereoelectronic properties of the catalyst or reagent. This short review will provide a summary of selected examples of catalyst- and reagent-controlled site-divergent intermolecular functionalization of C(sp3)–H bonds, the factors responsible for modulating the site selectivity of these reactions, and will identify potential areas worthy of future research in this field.