Dioxiranes synthesis

Murray RW, Jeyaraman R. Dioxiranes synthesis and reactions of methyldiox-iranes. J Org Chem 1985 50 2847-53. 

Burke CP, Shi Y (2006) Regio- and enantioselective epoxidation of dienes by a chiral dioxirane synthesis of optically active vinyl cis-epoxides. Angew Chem Int Ed 45 4475-... 

This synthesis is shown in Scheme 13.59. Two enantiomerically pure starting materials were brought together by a Wittig reaction in Step C. The aldol addition in Step D was diastereoselective for the anti configuration, but gave a 1 1 mixture with the 6S, 1R-diastereomer. The stereoisomers were separated after Step E-2. The macrolactonization (Step E-4) was accomplished by a mixed anhydride (see Section 3.4.1). The final epoxidation was done using 3-methyl-3-trifluoromethyl dioxirane. 

Asymmetric epoxidation of olefins is an effective approach for the synthesis of enan-tiomerically enriched epoxides. A variety of efficient methods have been developed [1, 2], including Sharpless epoxidation of allylic alcohols [3, 4], metal-catalyzed epoxidation of unfunctionalized olefins [5-10], and nucleophilic epoxidation of electron-deficient olefins [11-14], Dioxiranes and oxazirdinium salts have been proven to be effective oxidation reagents [15-21], Chiral dioxiranes [22-28] and oxaziridinium salts [19] generated in situ with Oxone from ketones and iminium salts, respectively, have been extensively investigated in numerous laboratories and have been shown to be useful toward the asymmetric epoxidation of alkenes. In these epoxidation reactions, only a catalytic amount of ketone or iminium salt is required since they are regenerated upon epoxidation of alkenes (Scheme 1). 

Section II covers the synthesis of the cyclic peroxides with medium ring size from 5 to 7. Section HI covers the synthesis of 1,2,4-trioxanes. Classification in sub-sections and sub-sub-sections is done according to the type of reaction by which the cyclic peroxide system is formed. Syntheses of dioxirans, 1,2-dioxetanes, trioxolanes (ozonides), tetrox-anes, and macrocyclic peroxides are not discussed in this review. 

Electron-rich alkenes are the more reactive jr-bond snbstrates towards epoxidation by the electrophilic dioxiranes Some typical examples of these oxidations are snm-marized in Scheme 2. Since the resnlting epoxides are nsnally hydrolytically and ther-molytically qnite labile, snch oxidations are best carried ont with isolated dioxiranes. For example, the 8,9 epoxide of the well-known aflatoxin B, postnlated as potent carcinogen in the oxidative metabolism of this natural product, escaped numerous efforts to prepare it by conventional epoxidations because of its sensitivity towards hydrolysis . The synthesis of this labile epoxide was readily accomplished by employing a solution of the isolated DMD at room temperature (equation 2), and its mutagenicity unequivocally... 

Highly diastereoselective dioxirane epoxidations have been widely employed in organic synthesis. For example, in the total synthesis of epothilone B, an important antitumor agent , the required epoxide was obtained in good yield and diastereoselectivity by DMD oxidation (equation 7) . ... 

Sulfur compounds with divalent sulfur functionalities are much more prone to dioxirane oxidation on account of their higher nucleophilicity compared to the above-presented oxygen-type nucleophiles. Examples of this type of dioxirane oxidation abound in the literature. Such a case is the oxidation of thiols, which may be quite complex and afford a complex mixture of oxidation products, e.g. sulfinic acids, sulfonic acids, disulfides, thiosulfonates and aldehydes , and is, therefore, hardly useful in synthesis. Nevertheless, the oxidation of some 9i/-purine-6-thiols in the presence of an amine nucleophile produces n >( -nucleoside analogs in useful yields (equation 19). This reaction also displays the general chemoselectivity trend that divalent sulfur functionalities are more reactive than trivalent sp -hybridized nitrogen compounds P. 

Be this as it may, the CH oxidation has become an attractive and promising preparative method in natural-product synthesis. For example, dioxiranes have been used to introduce selectively a hydroxy group at the C-25 position of steroids, a challenging task not readily achieved with other oxidants. A specific case is the TFD oxidation of brassinosteroid (equation 33) . 

Alkyl hydroperoxysilanes, preparation, 783 Alkyl hydrotrioxides, structural chemistry, 132 Alkyl iodides, dioxirane oxidation, 1158 Alkyl methyl sulfonates, alkyl hydroperoxide synthesis, 673... 

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... 

Epinephrine, chemiluminescence, 647 6-Epiplakortolide E, synthesis, 256, 257 Epithelial cells, ozone effects, 612 Epothilone B, dioxirane epoxidation synthesis, 1145... 

Hydroxyhydroperoxides, synthesis, 313-14 Hydroxylamine, dioxirane oxidation, 1151 Hydroxylation... 

T-bonds, C-H dioxirane oxygen insertion, 1138-9, 1158-63 trarw-Sabinene, synthesis, 891... 

C-H bond unreactive to insertion, 1160 dioxirane oxidation, 1156 Sulfonic acids, C-H bond unreactive to insertion, 1160 Sulfonyl endoperoxides parasiticidal activity, 1309 synthesis, 1306-9, 1332 Sulfonyl peroxides, 1001-2, 1004-7 Sulfonylperoxy radical, superoxide reactions, 1035-9 Sulfoxidation... 

Teeth whiteners, percarbamide, 623 Temperature, reaction rates, 903-12 Terminal olefins, selenide-catalyzed epoxidation, 384-5 a-Terpinene, peroxide synthesis, 706 a-Terpineol, preparation, 790 Terrorists, dialkyl peroxide explosives, 708 Tertiary amines, dioxirane oxidation, 1152 Tertiary hydroperoxides, structural characterization, 690-1... 

Thiophene, dioxirane oxidation, 1156 Thiourea, dialkyl peroxide synthesis, 706 1,4-Thioxane, oxidation, 805-6 Thiyl radicals, triplet oxygen domino reactions, 221-3, 224, 225, 226 THPO (1,2,3,4-tetrahydronaphthyl hydroperoxide), 331-2 Thromboxanes, from arachidonic hydroperoxides, 612... 

The present volume comprises 17 chapters, written by 27 authors from 11 countries, and deals with theoretical aspects and structural chemistry of peroxy compounds, with their thermochemistry, O NMR spectra and analysis, extensively with synthesis of cyclic peroxides and with the uses of peroxides in synthesis, and with peroxides in biological systems. Heterocyclic peroxides, containing silicon, germanium, sulfur and phosphorus, as well as transition metal peroxides are treated in several chapters. Special chapters deal with allylic peroxides, advances in the chemistry of dioxiranes and dioxetanes, and chemiluminescence of peroxide and with polar effects of their decomposition. A chapter on anti-malarial and anti-tumor peroxides, a hot topic in recent research of peroxides, closes the book. 

In recent years, dioxiranes have become workhorses for a variety of selective transformations in organic synthesis, from epoxidation of alkenes to the conversion of alcohols into fee corresponding ketones <99CJC308>. Dioxirane-mediated epoxidation continues to be the method of choice for complex substrates wife acid-sensitive functionality. Thus, fee dimethyl-dioxirane (DMD)-mediated epoxidation of the silylated stilbene lactam 159 has been reported as a key step in fee synthesis of protoberberines <99JOC877>. 

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