Synthesis of Polysubstituted Furans by a Sonogashira-Cyclization Route

Significance

Reported is a two-step synthesis of furans, starting by a Sonogashira coupling of (Z)-3-iodoalk-2-en-1-ols with 2-alkynols. The resulting isolated alkyn-ene diols are treated with a mixture of catalytic Au(PPh₃)Cl/AgOTf to afford the polysubstituted 2-(1-alkenyl)-furans in moderate to good yields over two steps. The studied substrate scope comprised only of alkyl/aryl substituents on both starting components. Secondary alkyn-2-ols gave mixtures (1:1) of the E- and Z-isomers and primary alkyn-1-ols afforded only low yields (˜20%) of products.