Palladium-Mediated Intramolecular Carbonylative Annulation of o-Alkynylphenols To Synthesize Benzo[b]furo[3,4-d]furan-1-ones

[reaction in text] The carbonylative annulation of o-alkynylphenols mediated by PdCl(2)(PPh(3))(2) and dppp in the presence of CsOAc at 55 degrees C in acetonitrile under a balloon pressure of CO generates functionalized benzo[b]furo[3,4-d]furan-1-ones in good yields. This novel synthetic approach provides a highly efficient method for diversification of the benzofuran scaffold for combinatorial synthesis.