Cooling the reaction to room temperature and switching solvents to dichloromethane suppressed the deleterious formation of side products and smoothly afforded the iodinated product 2a in 79% yield. We characterized the thermal stability of 2a by differential scanning calorimetry (DSC) due to a recent report on the instability of related compounds (See Supporting Information). The diphenylamide analog 1b was selected as a model substrate with a chromophore to aid reaction monitoring for optimization. When 1b was treated with 0.5 equiv DIH and irradiated for four hours, 2b was observed to form with 72% conversion. With additional DIH, the conversion increased to >90% (Table , Entries 2, 3).