ORGN 674 |
| 4-Iodo-1,1,2,2-9,9,10,10-octafluoro[2 2]paracyclophane (IAF4) was treated with potassium t-butoxide in butyl ether to generate 4,5-dehydo-1,1,2,2,9,9,10,10- octafluoro[2 2]paracyclophane (AF4-yne), which underwent facile reactions with benzene, naphthalene, etc. to give high yields of Diels-Alder adducts. No t-butoxide addition product was observed. Analogously, 4,15-diiodo-AF4 gave the corresponding bis-Diels-Alder adducts, also in high yields. Same results were obtained when the same arynes were generated via the Cadogan method, AF4-(N-nitroso)-4-acetamide. However, curiously, only the latter method of generation of the aryne allows Ene- reactions to proceed when the substrates are olefins, whereas using the t-butoxide method leads to reduction of IAF4 to AF4. The mechanism of this unusual Ene reaction selectivity has been studied, using deuterated reactants or solvents to distinguish between ionic or radical pathways. When 4-nitro AF4 was treated with KOBut and DOBut (1:1) in butyl ether at room temperature as a control reaction to determine D-exchange rate, unexpectedly, no deuterium exchange was observed, but instead a new product was obtained quantitatively. The nature of this product and the mechanism of this reaction will be discussed, as will the overall mechanistic aspects of this series of reactions.
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Physical Organic Chemistry: Calculations, Mechanisms, Photochemistry, and High-Energy Species
1:00 PM-5:00 PM, Wednesday, 16 March 2005 Convention Center -- Room 11A, Oral
Division of Organic Chemistry |