Copper-Catalyzed Divergent Rearrangement Reactions of Propargyl Ethers.

The transformation of readily available materials into high-value-added chemicals through rearrangement processes has always been a hot topic and a significant challenge in organic synthesis. Herein, we report a Cu-catalyzed divergent rearrangement reaction of propargyl ethers to access indenes and benzofurans via the 1,4-aryl migration-cyclization reaction and [3,3]-σ-rearrangement, respectively. Without the use of an excessive reductant and strong protic acid, the present method exhibits excellent functional group compatibility and therefore has diverse chemical transformations. Furthermore, the atom and step economical protocol, readily accessible starting materials, and mild reaction conditions give this novel method potential for applications in organic synthesis.