Synthesis of trifluoromethyl-group-containing cyclopentadienones by the palladium-catalyzed [2 + 2 + 1] cycloaddition of aryl- and trifluoromethyl-group substituted internal alkynes and carbon monoxide

We investigated the palladium-catalyzed [2 + 2 + 1] cycloaddition of aryl- and trifluoromethyl-group-substituted internal alkynes and carbon monoxide, and revealed that the PdBr2 effectively catalyzed the intended reaction. The PdBr2-catalyzed reaction smoothly proceeded and provided aryl- and trifluoromethyl-group-containing cyclopentadienone derivatives in up to 92% yield.