Ruthenium(II)‐Catalyzed Synthesis of Spirobenzofuranones by a Decarbonylative Annulation Reaction

Abstract The first decarbonylative insertion of an alkyne through C−H/C−C activation of six‐membered compounds is reported. The Ru‐catalyzed reaction of 3‐hydroxy‐2‐phenyl‐chromones with alkynes works most efficiently in the presence of the ligand PPh 3 to provide spiro‐indenebenzofuranones. Unlike previously reported metal‐catalyzed decarbonylative annulation reactions, in the present decarbonylative annulation reaction, the annulation occurs before extrusion of carbon monoxide.