Visible-Light Photoredox-Catalyzed Decarboxylation of α-Oxo Carboxylic Acids to C1-Deuterated Aldehydes and Aldehydes

The synthesis of high-value-added C1-deuterated aldehydes would improve the availability of deuterated lead compounds for deuterium-labeled drug discovery. Herein, we develop a metal-free synthesis of C1-deuterated aldehydes with D₂O from α-oxo carboxylic acids at ambient temperature. Via visible-light photoredox-catalyzed decarboxylation, stoichiometric reductants and oxidants were avoided. Various functional groups were tolerated and resulted in C1-deuterium aldehydes in up to 92% yield and 91-97% D incorporation under mild conditions. This method is also applied to the synthesis of various aldehydes. Primary mechanistic studies indicate that the catalytic pathway occurs via a reductive quenching pathway followed by hydrogen atom transfer.