Phenyl bridging in ring-substituted cumyloxyl radicals. A product and time-resolved kinetic study.

The reactivity of cumyloxyl radicals bearing cyclopropyl and 2,2-diphenylcyclopropyl groups in the para position has been investigated. Depending on radical structure, products deriving from C-C beta-scission and/or cyclopropyl ring-opening are observed, supporting the hypothesis that cumyloxyl (and, more generally, arylcarbinyloxyl) radicals exist in equilibrium with 1-oxaspiro[2,5]octadienyl radicals, in full agreement with the previously proposed mechanism for the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals.