Palladium-catalyzed ionic liquids-mediated cascade carbonylative alkynylation of diaryl ethers with alkynes

Abstract

An NHC-palladium-catalyzed ionic liquid-mediated cascade carbonylative alkynylation of diaryl ethers with alkynes in basic “task-specific” ionic liquid for the assembly of structurally diverse alkynones is presented. In the presence of 1 ​mol% of IPr^Ph2-Pd-Cin-Cl as the catalyst, ionic liquid [Aemim]BF₄ as the solvent and the base, a wide array of terminal alkynes and diaryl ethers could be excellently tolerated. It is particularly noteworthy that both NHC-palladium catalyst and basic “task-specific” ionic liquid play a crucial role in this catalytic system. This cascade carbonylative alkynylation features good yields (up to 92%), good functional group compatibility (33 examples), excellent regioselectivity, and a green synthetic process. Of note, the robustness and potential of this protocol have also been successfully demonstrated by the valorization of polyphenylene oxide wastes, gram scale experiment and the recycling experiment (7 times).