The ene-type reaction resulted in a very high calculated energy profile, whereas the nucleophilic attack via TS2 (15.0 kcal/mol) led to intermediate III. Then, intermediate IV and fluorocarbonothioate derivative 7b form via TS3 (8.9 kcal/mol). 7b is easily hydrolyzed in presence of trace amount of water to yield 7a, which was experimentally observed. Next, the sulfur anion attacks the ipso-carbon of the iodine in a Smiles-type rearrangement via TS4 (18.0 kcal/mol), to yield the desired product 3a. The energy profile was also calculated without the potassium cation, which resulted in a considerably higher energy profile. This indicates that the potassium cation plays a key role in the mechanism by stabilizing the ionic intermediate and the fluoride. Such influence has been previously reported in reactions involving hypervalent iodine reagents. Scheme 4. Mechanistic studies. Reaction conditions i) DMF, 40 °C, 12 h, ii) MeI, DMF, rt, 2 h. NMR yields are reported using 1,3,5-trimethoxybenzene.