Zirconium-Catalyzed Synthesis of 6-(Trifluoromethyl)-2-pyran-2-ones via C-C Bond Cleavage.

A strategy for the annulation reaction of alkynones with ethyl 4,4,4-trifluoro-3-oxobutanoate through C-C bond cleavage is described. The zirconium-catalyzed transformation provides access to a wide range of structurally diverse 6-(trifluoromethyl)-2-pyran-2-ones in moderate to good yields, utilizing NaCO as a base. Further transformations into trifluoromethylated arene derivatives have been demonstrated as well. Furthermore, plausible reaction pathways are proposed by conducting various control experiments and isolating a β-diketone intermediate (X-ray) containing an intramolecular hydrogen bond.