| Abstract
| - We have studied oxidation reactions using a synthetic heme−thiolate (SR complex) in order toascertain the contributions of multiple intermediates derived from heme−thiolate to the oxygen atom transferreaction to substrate. First, degradation of peroxyphenylacetic acid (PPAA) was examined in the presenceof various substrates. The O−O bond cleavage mode of PPAA was clearly dependent on the reactivity ofthe substrate, and an easily oxidizable substrate enhanced heterolytic O−O bond cleavage. Second,competitive oxidations of cyclooctane and cyclooctene were carried out with various peroxybenzoic acidscontaining a series of substituents at the para-position as an oxygen source. The ratios of alkanehydroxylation rate/alkene epoxidation rate were dependent on the nature of the para-substituent of theoxidant. We conclude that substrate and oxidant interact with each other during the oxygen atom transferreaction, that is, oxidation reaction occurs before O−O bond cleavage, even in the reaction catalyzed byheme−thiolate, which is considered to promote O−O bond cleavage. The results of an 18O-incorporationstudy that is frequently performed to determine the active intermediates derived from iron porphyrins wereconsistent with this conclusion.
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