Cobalt-catalysed sp² C–H bond functionalization has attracted considerable attention in recent years because of the low cost of cobalt complexes and interesting modes of action in the process. In comparison, much less efforts have been devoted to the sp³ carbons. Here we report the cobalt-catalysed site-selective dehydrogenative cyclization of aliphatic amides via a C–H bond functionalization process on unactivated sp³ carbons with the assistance of a bidentate directing group. This method provides a straightforward synthesis of monocyclic and spiro β- or γ-lactams with good to excellent stereoselectivity and functional group tolerance. In addition, a new procedure has been developed to selectively remove the directing group, which enables the synthesis of free β- or γ-lactam compounds. Furthermore, the first cobalt-catalysed intermolecular dehydrogenative amination of unactivated sp³ carbons is also realized.

In the past decade, selective C–C and C-heteroatom bond construction through palladium-catalyzed direct C–H bond functionalization has been extensively studied by employing a variety of directing groups. Within this category, direct asymmetric C(sp²)–H and C(sp³)–H activation for the construction of highly enantiomerically enriched skeletons still progressed at a slow pace. This minireview briefly introduces the major advances in the field for palladium-catalyzed direct asymmetric C–H bond functionalization via the directing group strategy.