6-Exo-dig and/or 7-endo-dig iodocyclization reactions of functionalized acetylenic derivatives with ICl are disfavored in comparison with the corresponding electrophilic addition reactions providing regioselectively (E)-1-chloro-2-iodoethene derivatives. On the contrary, 6-endo-digand 5-exo-dig iodocyclizations of methyl ynoates with ICl seem to be favored in comparison with the corresponding electrophilic addition reactions.