2-Pyridone-Enhanced Mn-Catalysis for the Synthesis of ortho-Deuterated Aromatic Nitriles

We herein present a method for the synthesis of ortho-deuterated aryl nitrile using Mn(CO)5Br as catalyst with CH3OD as deuteratium source, where the structure of aryl imidates is used for interconversion with a cyanide group. This method features a broad substrate range and excellent functional group tolerance, allowing late modification of various complex molecules with good yields and deuterium incorporation. Mechanistic studies suggest that 2-pyridone is crucial to the success of this chemistry, serving as an endogenous base that enhances the rate of hydrogen isotope exchange.