Gold-Catalyzed Cyclization of (Z)-2-En-4-yn-1-ols:  Highly Efficient Synthesis of Fully Substituted Dihydrofurans and Furans

[reaction: see text] The gold-catalyzed cyclization of (Z)-enynols offers an efficient and straightforward route to stereodefined (Z)-5-ylidene-2,5-dihydrofurans and fully substituted furans under extremely mild reaction conditions. Importantly, the results indicated that both the oxyauration and the proto-demetalation steps are highly stereoselective.