Palladium-catalyzed intramolecular hydroarylation of 4-benzofuranyl alkynoates. Approach to angelicin derivatives.

Intramolecular hydroarylation of 4-benzofuranyl alkynoates using Pd(OAc)(2) as catalyst took place selectively and efficiently, giving angular furocoumarin derivatives in high yields. The parent angelicin was obtained in 80% yield by this method. The starting 4-benzofuranyl alkynoates were easily accessible from readily available 4-hydroxybenzofurans and alkynoic acids.