Electron-poor alkenes dioxirane epoxidation

The epoxidation of electron-poor alkenes (Scheme 4) is more cumbersome, such that usually an excess of the dioxirane is required, prolonged reaction times (up to several days) and elevated temperatures (up to 60 °C), to achieve good conversions alternatively, the more reactive TFD may be employed . Again, the epoxide products of these substrates are hydrolytically more robust, so that the in-situ mode is a good choice for these substrates. It must be stressed that the dioxirane epoxidation of electron-poor alkenes offers an effective... 

The oxidation of organic substances by cyclic peroxides has been intensively studied over the last decades , from both the synthetic and mechanistic points of view. The earliest mechanistic studies have been carried out with cyclic peroxides such as phthaloyl peroxide , and more recently with a-methylene S-peroxy lactones and 1,2-dioxetanes . During the last 20 years, the dioxiranes (remarkable three-membered-ring cyclic peroxides) have acquired invaluable importance as powerful and mild oxidants, especially the epoxidation of electron-rich as well as electron-poor alkenes, heteroatom oxidation and CH insertions into alkanes (cf. the chapter by Adam and Zhao in this volume). The broad scope and general applicability of dioxiranes has rendered them as indispensable oxidizing agents in synthetic chemistry this is amply manifested by their intensive use, most prominently in the oxyfunctionalization of olefinic substrates. 

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