Gold-Catalyzed Controllable C2-Functionalization of Benzofurans with Aryl Diazoesters.

A ligand-controlled gold-catalyzed chemoselective C2-functionalization of benzofuran substrates with aryl diazoesters has been developed. The use of IPrAu(PhCN)BArF provides unprecedented dearomatization products bearing a newly formed carbon-carbon double bond at the C2 position of benzofurans. In contrast, the C2-alkylation products have been isolated as the major products for phosphite gold catalysis.