Synergistic Dual Activation Catalysis by Saccharin‐Based Ionic Liquids for Diastereoselective Synthesis of Ferrocene‐Appended Furopyranones, Furochromenones, and Benzofuranones

ABSTRACT A practical and straightforward strategy for the synthesis of ferrocene appended furopyranone, furochromenone, and benzofuranone via a metal‐free annulation reaction of imidazolium ylide with enone mediated by saccharin‐based ionic liquid has been reported. The mechanistic studies show an approach through synergistic dual activation of enone and imidazolium ylide via cation and anion of ionic liquid, respectively. This operationally simple protocol offers an easy and rapid access to a library of ferrocene appended furopyranone, furochromenone, and benzofuranone in moderate to good yields through the involvement of a six‐membered transition state.