Nickel‐Catalyzed Acyl Group Transfer of o‐Alkynylphenol Esters Accompanied by C−O Bond Fission for Synthesis of Benzo[b]furan.

Herein, we report the nickel‐catalyzed cascade C−O bond cleavage/cyclization of ortho‐alkynylphenyl ester to construct a 3‐acylbenzo[b]furan skeleton. As a result of reaction condition screening, the Ni(0)/IAd (1,3‐Di(1‐adamantyl)imidazole‐2‐ylidene) system was found to be optimal for catalytic conversion. Interestingly, the reaction exclusively gives 3‐acylbenzo[b]furan instead of a decarbonylated product frequently observed in reactions mediated by acyl‐nickel species. The catalyst loadings could be reduced to 5–10 mol %. We demonstrated the synthesis of a variety of functionalized 3‐acylbenzofuran derivatives. We conducted stoichiometric study of nickel complexes as well as density functional theory (DFT) calculations to support a possible reaction mechanism. [ABSTRACT FROM AUTHOR]