Allylic Hydroperoxide Rearrangement: β-Scission or Concerted Pathway?

Article abstract of DOI:10.1021/jo00232a004

The rearrangements of the allylic hydroperoxides derived from oleic acid have been studied.Two hydroperoxides are formed by singlet-oxygen oxidation of oleic acid trans-9-hydroperoxyoctadec-10-enoic acid (5) and trans-10-hydroperoxyoctadec-8-enoic acid (6).These hydroperoxides can be separated by reverse-phase chromatography.Rearrangement of 18O-labeled hydroperoxides (5 or 6) under a 32O2 atmosphere led to no incorporation of 16O into the rearrangement products.Similarly, rearrangement of 16O-labeled hydroperoxides (5 or 6) under a 36O2 atmosphere led to no incorporation of 18O into the rearrangement products.The hydroperoxide 5 rearranges to a mixture of 5 and trans-11-hydroperoxyoctadec-9-enoic acid and alcohols and ketones resulting from Russell termination steps.The results are discussed in terms of a concerted rearrangement of allylic peroxyl radicals proceeding through a five-membered-ring transition state.