Photoelectrochemical asymmetric catalysis enables site- and enantioselective cyanation of benzylic C–H bonds

The enantioselective functionalization of ubiquitous C( sp 3 )–H bonds is ideally suited for the construction of three-dimensional chiral structures. However, organic molecules often contain multiple C( sp 3 )–H bonds with a similar energy and steric environment, rendering the simultaneous control of site-, chemo- and stereoselectivity extremely challenging. Here we show the merger of molecular photoelectrochemistry with asymmetric catalysis for the highly site- and enantioselective cyanation of benzylic C( sp 3 )–H bonds. This example of photoelectrochemical asymmetric catalysis requires no chemical oxidant and exhibits an exceptional level of site selectivity and functional group tolerance, enabling not only the efficient conversion of feedstock chemicals but also the late-stage functionalization of complex bioactive molecules and natural products, including ones with multiple benzylic sites.