Synthesis of 4‐Arylcoumarins via Palladium‐Catalyzed Arylation/Cyclization of ortho‐Hydroxylcinnamates with Diaryliodonium Salts.

The palladium-catalyzed arylation/cyclization of ortho-hydroxylcinnamate ester derivatives by using diaryliodonium(III) salts has been developed. With this method, 4-arylcoumarins were easily prepared in good to excellent yields under base-free conditions. Additionally, this protocol provided an efficient alternative for the preparation of related 4-arylated coumarin compounds which are useful in the access to 5-lipoxygenase inhibitors.