Photochemical Deracemization of N ‐Carboxyanhydrides En Route to Chiral α‐Amino Acid Derivatives

Readily accessible, racemic N ‐carboxyanhydrides (NCAs) of α‐amino acids underwent a deracemization reaction upon irradiation at λ=366 nm in the presence of a chiral benzophenone catalyst. The enantioenriched NCAs (up to 98 % ee ) serve as activated α‐amino acid surrogates and, due to their instability, they were directly converted into consecutive products. N ‐Protected α‐amino acid esters were obtained after reaction with MeOH and N ‐benzoylation (14 examples, 70 %‐ quant ., 82–96 % ee ). Other consecutive reactions included amide (ten examples, 65 %‐ quant ., 90–98 % ee ) and peptide (three examples, 75–89 %, d. r.=97/3 to 94/6) bond formation. Limitations of the method relate for some NCAs to issues with solubility, photooxidation, and high configurational lability.