| Résumé | Photochemically generated tert-butoxyls abstract an allylic hydrogen atom from hexamethyl(Dewar benzene). The resultant allylic radical [g = 2.00264, aH(2 H) = 12.40 G, aH(3 H) = 15.48 G] can be observed from 150 to 375 K. The same radical is formed by hydrogen abstraction from hexamethylprismane even at 140 K. In this case it is presumed to arise by two successive cyclopropylcarbinyl ring-opening rearrangements. Hydrogen abstraction from 1,2,4,5,6-pentamethyl-3-methylenetricyclo[3.1.0.02,6]hexane (the hexamethylbenzvalene isomer) also gave an allylic radical [g = 2.00259, aH(2 H) = 10.28 G, aH(3 H) = 16.98 G] which could be observed from 150 to 225 K. At higher temperatures this radical probably undergoes a rearrangement to a substituted cyclopropyl radical. The latter could not be detected, probably because of its high reactivity. © 1981 American Chemical Society. |
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