<i>syn</i>-Fluoro- and -Oxy-trifluoromethylation of Arylacetylenes

One-step concurrent fluoro-trifluoromethylation across the triple bond of arylacetylenes in a <i>syn</i> mode is enabled by the collaboration of (phen)­Cu<sup>III</sup>(CF<sub>3</sub>)<sub>3</sub> and CsF that produces chemo-, regio-, and stereoselectively (Z)-α-fluoro-β-CF<sub>3</sub> styrenes. This method can be extended to achieve <i>syn</i>-oxy-trifluoromethylation and <i>syn</i>-aryl-trifluoromethylation of alkynes using phenoxides, alkoxides, or phenylboronic acid in place of CsF. It opens up new opportunities for preparing various functionalized trifluoromethylated <i>Z</i>-alkenes and demonstrates the potential of Cu­(III)–CF<sub>3</sub> complexes in organic synthesis.