Substitution hydroperoxide cyclization

B. Cyclization of Hydroperoxides through Intramolecular Nucleophilic Substitution and Addition... 

Phenyl hydroperoxide, C-O distance, 103 (y-Phenylhydroperoxides, nucleophiUc substitution cyclization, 234-5 1 -Phenyl-3-methyl-3-butene, intrazeohte photooxygenation, 874-5 Phenyl substituted alkenes, photooxidation site selectivity, 839-42... 

Dioxocin 206 (X = CH=CH) was also obtained from the hydroperoxide-substituted phenanthrene-fused oxepine 281 upon reaction with stoichiometric amount of benzaldehyde or acetone and TFA. The formation of the dioxocin goes through the elimination of MeOH and consequent intramolecular cyclization of the oxygen on the stabilized carbocation (Scheme 55) <1998J(P1)3053>. 

Synthetic methods for preparation of 1,2,4,5-tetroxanes have been reviewed recently <2001COR601, 2002RMC113>. The most general method involves acid-catalyzed addition of hydrogen peroxide to carbonyl compounds and subsequent cyclization of the hydroperoxide intermediates. The direct synthesis is carried out normally in the presence of either sulfuric, perchloric, or methanesulfonic acids and affords symmetrically substituted tetroxanes (Equation 26). In many cases, for example, where the carbonyl compound is unsubstituted in the a-position, tetroxanes are contaminated with hexaoxonanes and open-chain hydroperoxides. Selective removal of the more reactive hydroperoxides can be achieved with dimethyl sulfide or potassium iodide. Recrystallization usually removes residual hexaoxonanes but, failing that, heating the mixture with perchloric acid in acetic acid can convert hexaoxonanes to tetroxanes or convert the thermodynamically less stable hexaoxonanes to more water-soluble lactones, which may facilitate the purification process <2002RMC113>. 

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