Oxygen atom transfer dioxiranes

D. Oxygen Atom Transfer from Dioxiranes and Carbonyl Oxides. 32... 

In the past decade more efficient code and faster computers have allowed the use of electron-correlated methods of calculation and this has opened this area of theoretical chemistry to a wide range of research groups. The present sequel will be focused mainly on recent theoretical studies on a variety of oxidative processes involving oxygen atom transfer. We will include an extensive description of the very recent chemistry of peroxyni-trous acid (HO—ONO), dioxiranes, peracids and alkyl hydroperoxides. Since chemically realistic molecular systems can now be treated at an adequate level of electron-correlated... 

Dimesityldioxirane, a crystalline derivative, has been isolated by Sander and colleagues and subjected to X-ray analysis. The microwave and X-ray data both suggest that dioxiranes have an atypically long 0—0 bond in excess of 1.5 A. Those factors that determine the stability of dioxiranes are not yet completely understood but what is known today will be addressed in this review. A series of achiral, and more recently chiral oxygen atom transfer reagents, have been adapted to very selective applications in the preparation of complex epoxides and related products of oxidation. A detailed history and survey of the rather remarkable evolution of dioxirane chemistry and their numerous synthetic applications is presented in Chapter 14 of this volume by Adam and Cong-Gui Zhao. Our objective in this part of the review is to first provide a detailed theoretical description of the electronic nature of dioxiranes and then to describe the nuances of the mechanism of oxygen atom transfer to a variety of nucleophilic substrates. 

Dioxirane chemistry is well documented . Extensive kinetic, stereochemical and 0-labeling data suggested that dimethyldioxirane is the oxygen-atom transfer reagent in the Oxone-acetone system . Murray and Jeyaraman have shown that dialkyl dioxiranes can be isolated by low-temperature distillation from the reaction mixture of oxone and ketone . 

B3LYP level, 4, 34-5, 38, 40, 41, 43 CCSD level, 3, 34-5, 43 dioxirane oxygen atom transfer, 34-5 QCISD level, 3, 34-5, 43 10-Deoxoartemisinin, synthesis, 289-90 10-Deoxoartemisitene, synthesis, 289-90 Deoxyartemisinin, not antimalarial, 1280-1, 1283... 

The potential transfer of an oxygen atom from dioxiranes to a ketonic carbonyl group has been disproved (Scheme 48).81... 

Dioxirane (RR C02) compounds are relatively new in the arsenal of the synthetic chemist, however since the isolation of dimethyldioxirane by Murray and Jeyaraman in 1985,146 it has become a very important oxidant for preparative oxygen transfer chemistry.147 The dioxiranes are ideal oxidants in that they are efficient in their oxygen atom transfer, exhibit high chemio- and regio-selectivities, act catalytically, are mild towards the substrate and oxidized product, and perform under strictly neutral conditions. The compounds are prepared from peroxymonosulfate and ketones under neutral to mildly alkaline conditions (Figure 2.46). 

Dioxiranes are extremely useful reagents for the epoxidation of alkenes under neutral conditions. Since the oxygen atom transfer to the alkene regenerates the initial ketone, this epoxidation is catalytic. Dioxiranes are easily generated by the action of an oxone (potassium persulfate) on a ketone (usually acetone) either in a biphasic mixture or in a homogeneous aqueous organic solution. 

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