Interrupting Base-Mediated Benzofuran Ring Transformation with Michael Acceptors

A simple two-stage approach for the synthesis of 3-(2-arylbenzofuran-3-yl)­propanoates and propanamides has been developed employing simple acrylates and acrylamides and readily available 3-aroylbenzofurans. The key step of this process involves a base-mediated ring opening of the 3-aroylbenzofurans and subsequent Michael addition of the resulting 1,3-dicarbonyl intermediate with acrylate/acrylamide, followed by the deformylation in one-pot. The resulting products undergo an acid-mediated dehydrative cyclization to arrive at these targets.