Cerium photocatalyzed dehydrogenative lactonization of 2-arylbenzoic acids

The first cerium photocatalyzed dehydrogenative lactonization of 2-arylbenzoic acids has been developed. This operationally simple protocol allows rapid access to synthetically useful coumarins on gram scale by employing CeCl 3 as a photocatalyst and O 2 as a terminal oxidant. Overall, this delivers an economical and environmentally amiable entry to diversely substituted coumarins, important structural motifs in bioactive molecules. Cerium photocatalytic dehydrogenative lactonization of 2-arylbenzoic acids yields synthetically useful benzo-3,4-coumarin derivatives in gram scale under mild reaction conditions.