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

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]BF 4 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). A palladium-catalyzed cascade carbonylative alkynylation of diaryl ethers with alkynes in “task-specific” ionic liquid was accomplished. Amino-functionalized ionic liquid [Aemim]BF 4 plays multiple crucial roles in this catalytic system, which not only acts as an environmentally friendly solvent, but also provides the basic environment, as well as activate palladium intermediate via hydrogen bond.