Abstract
Gold-catalyzed formal hetero-[4π+2π] cycloadditions of tert-butyl propiolates with carbonyl compounds proceeded efficiently to yield 4H-1,3-dioxine derivatives over a wide scope of substrates. With acetone as a promoter, gold-catalyzed cycloadditions of these propiolate derivatives with enol ethers led to the formation of atypical [4+2]-cycloadducts with skeletal rearrangement.