| Abstract
| - The electronic character of peroxyformic acid and dioxirane has been clarified by the analysis ofdonor−acceptor interactions in 16 transition states (TS) for the epoxidation of olefins. Is has beenshown that the olefins are attacked by peroxyformic acid (PFA) in an electrophilic way. A relationof the electronic character to reactivity has been found: the more electrophilic the attack on theCC bond is, the faster the reaction. In contrast, dioxirane (DO) has been identified as both anelectrophilic and nucleophilic oxidant, depending on the substituents at the CC double bond. Thesubstrates with electron-withdrawing groups are attacked by DO in a nucleophilic way. Thesereactions have comparably low activation barriers. For instance, the acrylonitrile epoxidation withdioxirane is significantly faster than the corresponding reaction with PFA and proceeds via atransition state with a smaller extent of reaction and a larger extent of asymmetry.
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