Copper-Catalyzed Annulation-Trifluoromethyl Functionalization of Enynones

The Cu(I)-catalyzed annulation-halotrifluoromethylation and cyanotrifluoromethylation of enynones have been established, enabling multibond formations of the synthesis of quaternary carbon-centered 1-indanones in moderate to good chemical yields. The reaction of enynones with Togni's reagent and chloro- or bromotrimethylsilane afforded halo- and CF₃-containing 1-indenones. However, the addition of K₃PO₄ as a base into the catalytic system led to forming cyano-anchored (Z)-1-indanones as major stereoisomeric products. This strategy exhibits remarkable compatibility with a wide range of enynones.