Copper/Silver-Mediated Direct ortho-Ethynylation of Unactivated (Hetero)aryl CH Bonds with Terminal Alkyne

A copper/silver‐mediated oxidative ortho‐ethynylation of unactivated aryl CH bonds with terminal alkyne has been developed. The reaction uses the removable PIP directing group and features broad substrate scope, high functional‐group tolerance, and compatibility with a wide range of heterocycles, providing an efficient synthesis of aryl alkynes. This procedure highlights the potential of copper catalysts to promote unique, synthetically enabling CH functionalization reactions that lie outside of the current scope of precious metal catalysis. A copper/silver‐mediated oxidative ortho‐ethynylation of unactivated aryl CH bonds with terminal alkyne has been developed using a removable bidentate directing group (PIP; see scheme) derived from 2‐(pyridine‐2‐yl)isopropylamine. The reaction provides an efficient synthesis of aryl alkynes with broad substrate scope, high functional‐group tolerance, and compatibility with a wide range of heterocycles.