Palladium and Brønsted Acid Co-Catalyzed Biginelli-like Multicomponent Reactions via in Situ-Generated Cyclic Enol Ether: Access to Spirofuran-hydropyrimidinones

Alkynol served as an enolizable carbonyl equivalent to react with (thio)urea and aromatic aldehydes, furnishing a variety of spirofuran-hydropyrimidinone compounds in good yields and excellent diastereoselectivities. The one-pot multicomponent reactions were realized with co-catalysis of palladium chloride and trifluoroacetic acid through a Biginelli-like tandem reaction pathway.