Construction of Benzofuran-3(2H)-one Scaffolds with a Quaternary Center via Rh/Co Relay Catalyzed C–H Functionalization/Annulation of N-Aryloxyacetamides and Propiolic Acids

An unprecedented synthesis of valuable benzofuran-3(2H)-one scaffolds with a quaternary center was developed via Rh/Co relay catalyzed C–H functionalization/annulation of N-aryloxyacetamides with propiolic acids in moderate to good yields. The reaction features the simultaneous construction of the benzofuran motif containing a C2 quaternary center and a C3 carbonyl group. The preliminary mechanism study verified that the O atom of C3 carbonyl group originates from molecular oxygen.