hydrogen-deuterium (H-D) exchange reaction on the benzylic site proceeded in D2O in the presence of a small amount of H2 gas. The use of the Pd/C-ethylenediamine complex [Pd/C(en)] as a catalyst instead of Pd/C led to the efficient deuterium incorporation into the benzylic site of O-benzyl protective groups without hydrogenolysis. These H-D exchange reactions provide a post synthetic and D(2)-gas-free deuterium-labeling
The enantioselective functionalization of ubiquitous C(sp3)âH bonds is ideally suited for the construction of three-dimensional chiral structures. However, organic molecules often contain multiple C(sp3)âH 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(sp3)âH 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. Asymmetric synthetic photoelectrochemical transformations are underdeveloped. Now, the combination of a photocatalyst, a chiral copper catalyst and an electrode allows the enantioselective cyanation of benzylic CâH bonds without a chemical oxidant.