Pd-Catalyzed Annulation of β-Iodovinyl Sulfones with 2-Halophenols: A General Route for the Synthesis of 3-Sulfonyl Benzofuran Derivatives

The palladium-catalyzed annulation between beta-iodovinyl sulfones and 2-halophenols or 1-bromo-2-naphthol or 2-bromo-3-pyridinol is presented. The annulation process involving oxa-Michael addition-elimination and intramolecular Heck reaction leading to form 2,3-disubstituted benzofurans (aryl benzofuryl sulfones) in good to high yields. The regioselective tandem construction of C-O and C-C bonds has been achieved with a variety of substitution patterns. Moreover, the tandem process is reliable at gram-scale reactions and a plausible mechanism is also proposed.