Au‐Ag Bimetallic Catalysis Providing 3‐Alkynyl Benzofurans from Phenols via Tandem C‐H Alkynylation/Oxy‐Alkynylation

The development of new methodologies enabling a facile access to valuable heterocyclic frameworks still is an important subject of research. In this context, we describe a dual catalytic cycle merging C-H alkynylation of phenols and oxy-alkynylation of the newly introduced triple bond by using a unique redox property and the carbophilic π acidity of gold. Mechanistic studies support the participation of a bimetallic gold-silver species. The one pot protocol offers a direct, simple and regio-specific approach to 3-alkynyl benzofurans from readily available phenols. A broad range of substrates, including heterocycles, is transferred with excellent functional group tolerance. Thus this methodology can be used for the late stage incorporation of benzofurans.