Carbon-hydrogen (C-H) bonds have long been considered unreactive and are inert to traditional chemical reagents, yet new methods for the transformation of these bonds are continually being developed(1-9). However, it is challenging to achieve such transformations in a highly selective manner, especially if the C-H bonds are unactivated(10) or not adjacent to a directing group(11-13). Catalyst-controlled site-selectivity-in which the inherent reactivities of the substrates(14) can be overcome by choosing an appropriate catalyst-is an appealing concept, and substantial effort has been made towards catalyst-controlled C-H functionalization(6,15-17), in particular methylene C-H bond functionalization. However, although several new methods have targeted these bonds in cyclic alkanes, the selectivity has been relatively poor(18-20). Here we illustrate an additional level of sophistication in catalystcontrolled C-H functionalization, whereby unactivated cyclohexane derivatives can be desymmetrized in a highly site-and stereoselective manner through donor/acceptor carbene insertion. These studies demonstrate the potential of catalyst-controlled site-selectivity to govern which C-H bond will react, which could enable new strategies for the production of fine chemicals.