Copper-Catalyzed (3+2) Annulation of 5-Ethynyloxazolidine-2,4-diones with Benzoylacetonitriles: Synthesis of Dihydrofuran Derivatives

The copper-catalyzed (3+2) annulation of 5-ethynyloxazolidine-2,4-diones with acylacetonitriles worked well under mild reaction conditions to afford biologically important 2,3-dihydrofuran derivatives having an amide moiety in moderate to high yields. A wide scope of easily accessible 5-ethynyloxazolidine-2,4-diones and acylacetonitriles were tolerated. The successful scale-up reaction demonstrated that the reaction is a useful method for the synthesis of 2,3-dihydrofuran derivatives.