Flexible Synthesis of Benzofuranones from ortho‐Alkynyl Phenols or Benzofurans

Abstract Benzofuranones are attractive synthetic targets in medicinal and natural products. The cycloisomerization of o ‐alkynyl phenol to benzofuran‐3(2H)‐one is reported here using gold(I) and Selectfluor. This benzofuranone can also be obtained from benzofuran without a gold catalyst. This study presents two appealing synthetic methods for benzofuran‐3(2H)‐ones that use readily available starting materials, have high chemoselectivity and operate under very mild conditions.