Iodine sets allenes ringing: A novel iodine‐promoted tandem cyclization reaction of but‐2‐yne‐1,4‐diol and 4‐aminobut‐2‐yn‐1‐ol derivatives leading to substituted 3,4‐diiodoheterocyclic compounds has been developed (see scheme). In this reaction, a trace amount of water is needed. Both the iodine anion and cation generated from I2 are used in the reaction. The resulting iodides can then be used in