Xu Yan, Wenbo Zhang, Li Li, Jinxing Jiang, Yaqin Cui, Yi Luo, Yanzhi Liu, Peng Wang, Kun Yuan, Pan‐Lin Shao, Chun‐An Fan
An efficient copper-catalyzed (4+1) tandem annulation has been established for the rapid construction of 2,3-disubstituted benzofurans. This method converts terminal alkynes and 2-(tosylmethyl)phenols using a dual-base system, proceeding via the in situ formation of ortho -quinone methides and alkynyl-copper(I) species. Combined density functional theory calculations and control experiments elucidate a mechanism proceeding through 1,4-conjugate addition, intramolecular cyclization, and base-promoted aromatization. This transformation not only provides a novel and efficient route to functionalized benzofuran motifs but also enriches the chemistry of alkynes and o -quinone methides in organic synthesis.