Oxidative cleavage with singlet oxygen

Selective oxidation. 5-Hydroperoxy 1,3-dienes, after protection as peroxy-acetals, undergo selective cleavage at the remote double bond. The hydroperoxides themselves are available from ene reaction of skipped dienes with singlet oxygen. 

Pr OH. Hydroperoxyindolines have been trapped by reduction with KBH4. In the photo-oxidation of aqueous indole-3-acetic acid and of its methyl ester using various sensitizers at different pHs, cleavage by singlet oxygen appears to compete with hydroperoxidation of the CH2 group. The mechanism of photo-oxidation of bacteriochlorophyll C derivatives has also been examined. ... 

The sensitized photo-oxidation of gurjunene (138) to form the epoxide (140), among other products, provides the first example of cyclopropane ring cleavage by singlet oxygen. The isolation of (140) is consistent with the... 

Toutchkine, A. and Clennan, E.L. (2000). A new mechanism for oxidative C-S bond cleavage during reactions of singlet oxygen with organic sulfides electronically dictated reaction selectivity in the persulfoxide intermediate. J. Am. Chem. Soc. 122, 1834-1835... 

The reaction mechanism for the aerobic oxidation of the pz to seco-pz can be attributed to a formal 2 + 2 cycloaddition of singlet oxygen to one of the pyrrole rings, followed by cleavage (retro 2 + 2) of the dioxetane intermediate to produce the corresponding seco-pz (160). This mechanism is shown in Scheme 29 for an unsymmetrical bis(dimethylamino)pz. Further photophysical studies show that the full reaction mechanism of the photoperoxidation involves attack on the reactant by singlet oxygen that has been sensitized by the triplet state of the product, 159. As a consequence, the kinetics of the process is shown to be autocatalytic where the reactant is removed at a rate that increases with the amount of product formed. 

Although these substrates are both inert to singlet oxygen, olefin oxidative cleavage was observed with superoxide. Furthermore, an oxidative equilibration of the olefin radical cations... 

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