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.