The Vicinal‐Diiodination of the HDDA‐Benzynes by <i>N</i> ‐Iodo‐ succinimide (NIS) Through a Radical Pathway

The 1,2-diradical reactivity of the HDDA-benzynes (thermal) has not been explored well in comparison to their ionic reactivity. Accordingly, the radical trapping reactions of these reactive intermediates are very scarce in literature. Herein, we report the iodine-radical trapping reaction of the HDDA-benzynes for the construction of structurally divergent vicinal-diiodo arenes. The N-iodosuccinimide (NIS) has been employed as the source of radical iodine under thermal heating conditions. The existence of the arene-radical intermediates and the radical mechanism has been supported by the EPR spectral analysis of the reaction mixture. Several fruitful control experiments suggested that the 4-iodination (mono-) of the HDDA-benzynes is faster than the 5-iodiniation. The process is general in terms of substituents on the diynes as well as the nature of the tethering units. To the best of our knowledge, this is the first report on the vicinal-diiodination as well as radical diiodination of HDDA-benzynes.