The redox-neutral approach to C-H functionalization.

The direct functionalization of C-H bonds is an attractive strategy in organic synthesis. Although several advances have been made in this area, the selective activation of inert sp(3) C-H bonds remains a daunting challenge. Recently, a new type of sp(3) C-H activation mode through internal hydride transfer has demonstrated the potential to activate remote sp(3) C-H linkages in an atom-economic manner. This Minireview attempts to classify recent advances in this area including the transition to non-activated sp(3) C-H bonds and asymmetric hydride transfers.