Copper-Catalyzed Intramolecular Hydroalkoxylation of α-(1-Hydroxy-1-alkyl- and -aryl)methylallenoates by a 5-Endo Mode for Preparation of 2-Alkyl- and 2-Aryl-2,5-dihydrofurans

Ethyl alpha-(1-hydroxy-1-alkyl)methylallenoates and alpha-(1-hydroxy-1-aryl)methylallenoates containing not only electron-donating groups but also an electron-withdrawing group on the aryl group at the alpha-position have been shown to undergo an efficient and selective copper-catalyzed intramolecular hydroalkoxylation to give functionalized 3-ethoxycarbony1-2-alkyl- and -aryl-2,5-dihydrofurans in good to excellent yields through a 5-endo mode.