Gold(I)-Catalyzed Angle Strain Controlled Strategy to Furopyran Derivatives from Propargyl Vinyl Ethers: Insight into the Regioselectivity of Cycloisomerization

A unique strategy for the regiospecific synthesis of bicyclic furopyran derivatives has been developed via a gold(I)-catalyzed propargyl-Claisen rearrangement/6-endo-trig cyclization of propargyl vinyl ethers. The introduction of angle strain into the substrates significantly altered the reaction's regioselectivity. Insight into the regioselectivity of the cycloisomerization was obtained with density functional theory calculations.