Palladium-Catalyzed Intramolecular Migratory Cycloisomerization of 3-Phenoxy Acrylic Acid Ester via C–O Bond Cleavage and C–O/C–C Bonds Formation for 2,3-Disubstituted Benzofurans Synthesis

Migratory cycloisomerization using transition metal catalyst is useful for synthesizing substituted heterocyclic compounds. We achieved palladium-catalyzed migratory cycloisomerization of 3-o-alkynylphenoxy acrylic acid ester derivatives to give 2,3-disubstituted benzofurans. Although there are several reports of benzofuran synthesis with palladium-catalyzed migratory cycloisomerization, migratory groups are limited to allyl and propargyl groups. This report is the first example of benzofuran synthesis with palladium-catalyzed cycloisomerization of C(sp2)-O bond cleavage.