Direct Decarboxylative Giese Addition of Unprotected Amino Acids: A Cascade Access to γ-Lactams

Unprotected amino acids were developed as precursors of α-aminoalkyl radicals under visible-light photoredox catalysis. Single-electron oxidation of deprotonated amino acids followed by decarboxylation generated α-amino radicals, which participated in intermolecular Giese-type additions to electron-deficient alkenes. The reaction proceeds without protection of the amino group and provides direct access to secondary and tertiary amine frameworks. The free amino functionality also enables a cascade process in which the initially formed adduct undergoes intramolecular cyclization to afford γ-lactam products. Electrochemical analysis and control experiments support a mechanism involving base-assisted oxidation of the amino acid and subsequent radical generation. This study establishes an efficient strategy for the generation and utilization of α-aminoalkyl radicals from readily available amino acids and demonstrates their utility in C–C bond formation.