Siddique Khan
Indian Institute of Technology Madras, India
Title: The vicinal-diiodination of the HDDA-benzynes by N-Iodo- succinimide
Biography
Biography: Siddique Khan
Abstract
The HDDA reaction forms polycyclic benzyne intermediates via [4+2] cycloaddition between tethered alkyne and 1,3-diyne, yielding complex benzenoid products after trapping reactions.1,2 We devised and developed a versatile method for crafting dihaloarenes by trapping HDDA benzynes using N-halosuccinimides respectively. Here, the iodine- radical trapping reaction of the HDDA-benzynes for the construction of structurally divergent vicinal-diiodo arenes has been discovered and developed. Under thermal conditions, the N-iodosuccinimide was employed as the source of iodine radicals. EPR spectral analysis of the reaction mixture helped us to prove the existence of the radical intermediates and supported the proposed radical mechanism. A series of fruitful control experiments suggested that the 4-iodination (mono-) of the HDDA-benzynes is faster than the 5-iodiniation for both tetraynes as well as triynes. The iodine radical trapping reaction of the HDDA- benzynes was found to be faster than many of the intermolecular trapping reactions. The process is very broad in terms of the nature of the tethering units and substituents on the diynes. To the best of our knowledge, this is only the third report on the 1,2-diradical reactivity of the HDDA-benzynes and first one with experimental support for the radical mechanism.4 This presentation unveils our effort towards HDDA arynes using halogen based reagents.