Alkanes dioxirane oxyfunctionalization

Direct insertion into an X—H a bond constitutes the highlight of dioxirane chemistry . Besides the insertion of a dioxirane oxygen atom into an alkane acH bond, for practical purposes a most valuable oxyfunctionalization, also the more facile insertion into the asiH bond is known, a convenient and chemoselective method of preparing silanols. 

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. 

A new approach to the oxyfunctionalization of alkanes with isolated dioxiranes has been reviewed. Dioxiranes achieve oxidation of alkanes with high selectivity for both... 

The unusual reactivity of dioxiranes is impressively exhibited in their ability to insert into C — H bonds (Scheme 7) [28]. Thus, tertiary alkanes are oxidized to their respective alcohols [29]. In the example shown, the insertion took place with complete retention of configuration at the chirality center. 1,3-Dicarbonyl derivatives [30] are hydroxylated with high efficiency, but more than likely the intermediary enol is being oxyfunctionalized. Secondary alcohols are transformed into ketones, a specific example is the oxidation of the epoxy alcohol in the rosette [31], In an attempt to epoxidize the hydroxy acrylic ester [22], the epoxy 1,3-dicarbonyl product was obtained, although in low yield in accord with its rather reluctant nature towards oxidation. 

Direct Functionalization of C-H Bonds by Dimethyl-dioxirane. The efficient oxyfunctionalization of simple, unactivated C-H bonds of alkanes under extremely mild conditions undoubtedly is one of the major highlights of dioxirane chemistry. ... 

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