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DOI: 10.1055/sos-SD-043-00126

Gilchrist, T. L.Science of Synthesis, (200843214.

Diiodoarenes in which the two iodo substituents are para to one another are potential sources of para-arynes. This has led to the successful matrix isolation and characterization of tetrafluoro-1,4-didehydrobenzene (224) from 1,2,4,5-tetrafluoro-3,6-diiodobenzene (223) (Scheme 81).[‌289‌] On irradiation of diiodobenzene 223 at 254nm in a neon matrix at 3K, iodine atoms are eliminated in a stepwise manner. A species is formed that shows IR absorption maxima at 1516, 1507, 1117, and 925cm1 and has been assigned the structure 224. A recombination reaction that regenerates the diiodobenzene 223 occurs when the matrix is warmed; broadband irradiation at 3K then produces a new species identified as the enediyne structure 225. Flash pyrolysis of 9,10-diiodoanthracene (226)[‌288‌] and matrix photolysis of 2,5-diiodothiophene (227)[‌290‌] have also been investigated for the generation of the corresponding para-arynes 9 and 228, but only products resulting from ring opening of the arynes have been detected.

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