Copper-Catalyzed\nRegioselective Annulation of β‑Keto\nEsters and Propargyl Acetates: Access to Polysubstituted Furans

A copper-catalyzed regioselective annulation reaction,\nconducted\nwithout ligands or oxidants, has been developed for the preparation\nof multisubstituted furans from the readily available starting materials,\nβ-keto esters and propargyl acetates. This process accommodates\na wide range of functional groups, resulting in furan skeletons with\ndiverse substitution patterns. The method’s potential synthetic\nutility is highlighted by its applicability in gram-scale preparations\nand late-stage modifications of natural products.