Singlet oxygen from triphenyl phosphite ozonide

While the reaction of singlet oxygen with silyl enol ethers was governed by competing prototropic and silatropic ene processes (see Section 2.3.2.1.3.ii), the interaction with dienol ethers displays a different mode of reactivity. Singlet oxygen generated from triphenyl phosphite ozonide at low temperature... 

NaOCl (Clorox) and 30% H2 02 reacts with (1) at -5 to -15° to form the endo-peroxide (2) in 37% yield. This substance readily rearranges at 45° to trans-benzene trioxide (3). Singlet oxygen generated from triphenyl phosphite ozonide (3, 323-324) reacts with (1) to form (2), but purification by subUma-tion results in conversion to (3). This trioxide also results from photolysis of (2) (27% yield). 

Values for Polymer and Model Compounds. 1,4-Polyisoprene and 1,4-polybutadiene are so sufficiently reactive toward singlet oxygen that we can conveniently obtain / -values by three methods (a) from oxygen-uptake rates by photosensitized oxidation at different polymer concentrations (b) by the initial disappearance rate of rubrene on photooxygenation of solutions with and without polymer (or model olefin) and (c) for 1,4-polyisoprene, by the amount of rubrene consumed upon addition of aliquots of triphenyl phosphite ozonide in the presence and absence of olefin or polymer. The treatment of data from methods (b) and (c) was modified to give /3-values directly from the following equations ... 

AUylic hydroperoxides. The product ratios of the allylic hydroperoxides obtained on oxidation of alkenes with singlet oxygen differ significantly from those obtained by base-catalyzed isomerization of /3-halo hydroperoxides, which involves perepoxide intermediates. A third mechanism must be operating in the reaction of triphenyl phosphite ozonide (3, 323-324 4, 559). This last reaction presumably proceeds by an ionic mechanism, since singlet oxygen is not formed at — 70° from the ozonide. ... 

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