Substituted Dihydroisoquinolinones by Iodide-Promoted Cyclocarbonylation of Aromatic α‑Amino Acids

Imidazolidinone derivatives of a range of aromatic α-amino acids, on treatment with phosgene and potassium iodide, undergo a mild Bischler–Napieralski-style cyclocarbonylation reaction that generates a tricyclic lactam by insertion of a CO group between amino acid nitrogen and the ortho position of the aryl substituent. Regio- and diastereoselective functionalization of the lactam generates a library of substituted dihydroisoquinolinones and their congeners in enantioenriched form.