Visible Light-Driven Benzylic C(sp 3 )–H Carboxylation Enables Synthesis of 13 C-Labeled (±)-α-Amino Acids with 13 C-Formate

¹³C-labeled α-amino acids are important molecules in biological studies and drug development. Cost-effective synthesis of α-amino acids with a high level of ¹³C incorporation under mild conditions remains limited. Herein, we report the development of a benzylic C(sp³)-H carboxylation method to prepare highly ¹³C-labeled α-amino acids, i.e., arylglycines, using near-stoichiometric and user-friendly sodium ¹³C-formate. The sequential reaction pathway of in situ ¹³C-carbon dioxide (CO₂) generation followed by C-H carboxylation via 1,2-HAT was suggested by mechanistic studies.