Chemoselective direct deuterodecarboxylation of free aliphatic carboxylic acids enabled by deuteron-coupled electron transfer

Decarboxylative deuteration of activated precursors (e.g., α-amino acids) is an effective method for installing deuterium atoms at activated positions; however, direct usage of unactivated aliphatic carboxylic acids remains a long-standing challenge for the construction of C(sp3)–D bonds at non-activated positions. Herein, we report a general and efficient photoinduced direct deuterodecarboxylation of free aliphatic carboxylic acids via synergistic acridine and thiophenol catalyst systems with D2O as the cost-effective deuterium source, achieving precise installation of a deuterium atom at non-activated positions. The present methodology features broad functional group tolerance and displays high chemoselectivity, enabling the late-stage deuteration of natural products and pharmaceuticals, with high levels of D-incorporation (up to 90 examples, up to 99% D). Moreover, a 50 mmol scale-up reaction in the continuous flow process has been demonstrated without loss of D-incorporation and greatly improves the production efficiency with a shortened reaction time from 12 h to 15 min.