Aromatic Deformylative Deuteration Enabled by Cobalt–Photocatalysis at Ambient Temperature

Aryl aldehydes are among the most readily accessible bulk chemicals. Deformylative deuteration provides access to value-added deuterium-labeled molecules; however, this transformation is largely unexplored and current methods usually require noble metal catalysts and high temperatures. Herein, we report an ambient-temperature deformylative deuteration of aryl aldehydes with D₂O as a deuterium source. The reaction is facilitated with a dual-catalytic system by combining light-induced hydrogen atom abstraction with cobalt-mediated decarbonylation and deuterolysis. Importantly, the protocol is featured by high deuteration efficiency, site-specificity, and broad functional group compatibility, extending its applicability to complex pharmaceutical small molecules.