NHC–palladium-catalyzed ionic liquid-accelerated regioselective oxyarylation of alkynes with diaryl ethers

Abstract

The first NHC–palladium-catalyzed regioselective oxyarylation of oxime ether in a task-specific ionic liquid via C(sp³)–O and C(sp²)–O bond cleavage of two different types of ethers for the assembly of structurally diverse 4-arylisoxazoles is described. Both the basic ionic liquid [C₃NH₂mim]Br and NHC–Pd catalyst IPr–Pd–Im–Cl₂ played an important role in this transformation. Notably, this new approach provides a practical and straightforward route to access a broad range of privileged 4-arylisoxazole structures with good yields and excellent regioselectivities. Significantly, this catalytic system can be recycled up to eight times without significant loss of catalytic activity.