Rhodium(III)-Catalyzed Dearomatizing (3 + 2) Annulation of 2‑Alkenylphenols and Alkynes

Appropriately substituted 2-alkenyl­phenols undergo a mild formal [3C+2C] cyclo­addition with alkynes when treated with a Rh­(III) catalyst and an oxidant. The reaction, which involves the cleavage of the terminal C–H bond of the alkenyl moiety and the dearomatization of the phenol ring, provides a versatile and efficient approach to highly appealing spiro­cyclic skeletons and occurs with high selectivity.