Initially, the coordination of the carboxylate oxygen atom of 1
to the electrophilic Rh(III) center and subsequent ortho C−H
rhodation afford the rhodacycle A. A subsequent reaction with
the in situ formed alkyne radical leads to the Rh(IV) complex
B, which then undergoes reductive elimination to give the
alkynylated product C.11 A subsequent metal-catalyzed
cyclization gives the desired product 3 or 5. The released
Rh(II) species is oxidized by silver(I) to regenerate the Rh(III)
species to accomplish the catalytic cycle.