Recent development of direct asymmetric functionalization of inert C–H bonds

The area of direct asymmetric functionalization of inert C–H bonds has attracted considerable attention in recent years. To realize this type of challenging but promising transformations, a lot of strategies have emerged including asymmetric C–H bond insertion by metal carbenoids or analogs, cross dehydrogenative coupling, [1,5]-hydride transfer, C–H bond functionalization involving a transient metal–carbon species and other miscellaneous methods. This review is intended to summarize and discuss the most recent developments (contributions mainly after 2009) within this area.