Electrochemical selective deuterium labelling of N-heteroarenes

Hydrogen-deuterium exchange (HIE) reaction is the most direct way to achieve the deuterium labeling as there is no need for extra pre-functionalization. Herein, we report an electrochemical selective deuterium labelling of N-heteroarenes using D2O. The formation of aromatic radicals has been directly identified by using the time-resolved electron paramagnetic resonance (EPR) technique under electrochemical conditions. Mechanistic studies revealed that the hydrogen/deuterium (H/D) exchange involved continuous redox of N-heteroarenes under paired electrolysis and the selectivity of deuteration was established by DFT calculations. This electrochemical synthesis method offers a promising avenue for deuterium incorporation at specific sites of aromatic compounds.