Transition-Metal-Catalyzed Direct C-H Functionalization under External-Oxidant-Free Conditions

The use of an 'internal' oxidant contained within a directing group has emerged as a practical strategy in metal-catalyzed direct C-H activations in recent years, owing to its being highly sustainable. This review presents the rapid advances of this novel strategy through analyzing and comparing the different types of internal oxidant in transition-metal-catalyzed C-H activation reactions. 1 Introduction 2 The N-O Bond as Internal Oxidant 2.1 The O-Linked Moiety as Leaving Group 2.1.1 N-Oxide 2.1.2 N-Acyloxy 2.1.3 Oxime 2.1.4 N-Methoxy or N-Hydroxy 2.1.5 N-Pivaloyloxy or O-tert-Butyloxycarbonyloxy 2.1.6 Miscellaneous 2.2 The N-Linked Moiety as Leaving Group 3 The N-N Bond as Internal Oxidant 4 The N-S Bond as Internal Oxidant 5 The S-Cl Bond as Internal Oxidant 5 The Si-H Bond as Internal Oxidant 6 Conclusion