The AgSbF-catalyzed cyclization of 2-diazo-3,5-dioxo-6-ynoates (ynones, ynamide) in alcoholic solvents affords γ-pyrones, whereas the AgOAc-catalyzed cyclization in 1,2-dichloroethane (DCE) produces 3(2H)-furanones. The cyclization reactions proceeded cleanly under mild reaction conditions, and the desired γ-pyrones or 3(2H)-furanones were obtained in excellent yield. It was observed for the first time that both the catalyst and solvent play key roles in the selective formation. This unique method for the reversal of regioselectivity proved to be highly efficient except for substrates with aliphatic and MeSi groups at the triple bond position.

No abstract

No abstract

A silver(i)-catalyzed tandem cyclization/cross-coupling reaction of enynones with iodonium ylides to construct carbon–carbon double bonds has been developed.