I₂/CF₃CO₂Ag-mediated iodolactonization of various allenoic acids to access versatile 6-to 9-membered ring vinylic iodolactones

Medium-sized lactones are important structural units, but their synthesis remains a great challenge. Herein, we report I-2/CF3CO2Ag-mediated iodolactonization of allenoic acids to synthesize various 6- to 9-membered ring vinylic iodolactones in 16-89% yield. This protocol not only develops a new cyclization strategy of allenoic acids, but also provides highly functionalized medium-sized lactones containing alkene and halogen groups.