Gold-Catalyzed Highly Efficient Access to 3(2H)-Furanones from 2-Oxo-3-butynoates and Related Compounds

[reaction: see text] The gold-catalyzed cyclization reactions of 2-oxo-3-butynoic esters or disubstituted-1,2-diones with a variety of nucleophiles are described, which offer an efficient and straightforward route to substituted 3(2H)-furanones under mild reaction conditions. The Au(III) catalysts are also highly effective in the hydration of these activated alkynes.