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.