Photochemical Deracemization of Chromanes and its Application to the Synthesis of Enantiopure Bioactive Compounds.

ABSTRACT: Chromanes are frequently encountered as chiral structure elements in active pharmaceutical ingredients (APIs). We have now discovered an access to enantiopure chromanes, which employs a 1:1 mixture of their enantiomers (racemate) in a photochemical deracemization reaction (21 examples, 71%-90% yield, 80%-99% ee). A chiral photocatalyst (10 mol%) acts by selective hydrogen abstraction at one chromane enantiomer and establishes a photostationary state in which the other enantiomer prevails. A thiol additive (20 mol%) was found to improve the enantioselectivity of the process. The mechanism of the reaction was investigated by experimental and quantum-chemical studies. The oxygen atom of the chromane locks the rotation around the exocyclic C─C bond to the amide by forming an intramolecular hyd

SUBMITTER: Ghosh B 

PROVIDER: S-EPMC12851019 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature