Palladium-catalyzed synthesis of 1,3,4-alkatrien-2-yldihydrofurans from 2,3-allenylacetylacetates and propargylic carbonates and their application to synthesize polysubstituted dihydrofurylcyclopentenones

An efficient route to 1,3,4-alkatrien-2-yldihydrofurans via a highly chemo- and regioselective palladium(0)-catalyzed coupling–cyclization reaction of 2-(2′,3′-allenyl)acetylacetates with propargylic carbonates was reported. The reaction proceeded smoothly under neutral conditions, affording the O-attacked five-membered products with a 1,3,4-trienyl substituent exclusively in good to excellent yields. The products can be efficiently applied to the synthesis of polysubstituted 2-(dihydrofuryl)cyclopentenone derivatives via a catalytic Pauson–Khand reaction under ambient conditions.