NIS/HFIP‐Mediated Synthesis of Indene‐Based β‐Iodoalkenyl Sulfides from Propargylic Sulfides

A tandem 1,3‐sulfur migration followed by iodocyclization reaction of propargylic sulfides in the presence of NIS in HFIP has been developed to synthesize indene‐based β‐iodoalkenyl sulfides. The choice of the reaction media is crucial to promote the reaction. The proposed mechanism involving the initial NIS activation by HFIP and favoring the sulfur migration of the starting propargylic thioether via cationic intermediates is experimentally supported. In addition, the suitability of selected indene‐based β‐iodoalkenyl sulfides as building blocks for subsequent C−C bond‐forming reactions has been demonstrated.