Gold-catalyzed Selective Oxidation Of 4-oxahepta-1,6-diynes To 2H-pyran-3(6H)-ones And Chromen-3(4H)-ones Via β-gold Vinyl Cation Intermediates

α-Oxo gold carbenes generated in situ via the gold-catalyzed selective oxidation of 4-oxahepta-1,6-diynes were effectively trapped by internal alkynes, resulting in the formation of 2H-pyran-3(6H)-ones, 3, and chromen-3(4H)-ones, 4, upon facile trapping the vinyl cation intermediates.