Selective Synthesis of C4-Functionalized Benzofurans by Rhodium-Catalyzed Vinylene Transfer: Computational Study on the Cyclopentadienyl Ligand

Benzofuran is a privileged structure in many bioactive
compounds;
however, the controlled synthesis of C2,C3-nonsubstituted benzofurans
has been scarce. In particular, cumbersome multistep processes are
inevitable for the most inaccessible C4-substituted isomers. Herein,
we report a Rh-catalyzed direct vinylene annulation of readily available m-salicylic acid derivatives with vinylene carbonate to
achieve selective construction of C4-substituted benzofurans. The
Weinreb amide directing group facilitated the following product derivatization.
The reaction mechanism was investigated by DFT calculations.