W-Chloroperoxybenzoic acid

The same result can be achieved in one step with w-chloroperoxybenzoic acid and water. Overall anti addition can also be achieved by the method of Prevost. In... 

However, reaction of 1,2,3-benzothiadiazole 3 with 30% hydrogen peroxide in a mixture of acetic acid and methanol for 45 days afforded product 37 (Equation 7) in 60% yield <1990CJC1950>. Oxidation of 1,2,3-benzothiadiazole 3 with a variety of other oxidizing agents (w-chloroperoxybenzoic acid, 30% hydrogen peroxide, hydrogen peroxide in methylene chloride-acetic acid mixtures, etc.) was unsuccessful. 

Substituted 1,2,3-triazoles are oxidized by w-chloroperoxybenzoic acid at the more basic N(3) to give the corresponding triazole A -oxides. The yield is lower if an electron-withdrawing substituent is present at the C(4) or C(5) position <87ACS(B)724>. 2-Alkyl-1,2,3-triazole-1-oxides are produced from the oxidative cyclization of alkyl hydrazono oximes <86ACS(B)262> see Section 4.01.8.1. 

Oxidation of thiazine sulfur to give 5, Wdioxides has been performed successfully on substituted 1,4-thiazines <1999TL6439> and 3-acetyloxyphenothiazine <1987JOC4000> using w-chloroperoxybenzoic acid (MCPBA). Another oxidant is hydrogen peroxide, which was used to carry out the same transformation on a 4//-benzothiazine... 

Oxidation of a methylenecycloproparene gives products of exocyclic double bond cleavage140. Epoxidation has been performed with /w-chloroperoxybenzoic acid and 2-hydroxyethanones result (equation 37). The choice of reagent ensured that oxaspiropen-... 

Photolytic ring expansion of a spirooxaziridine intermediate was central to the ring expansion of the cyclohexanone 324 to 326 (e.g., R = Bn) after initial imine formation from reaction of 324 with 325 the oxaziridine was then generated by oxidation of the imine with w-chloroperoxybenzoic acid (Scheme 41) <1997JOG654>. 

Condensed dithiatriazepine 160 was rapidly and cleanly converted into dithiazolc-.Y-oxide 150 by oxidation with w-chloroperoxybenzoic acid (MCPBA) in dichloromethane at room temperature (Equation 45) <1998CC1207>. 

Oxidation of similarly substituted 3,6-dihydro-27/-selenines 91 with w-chloroperoxybenzoic acid affords the corresponding selenopyrans 92 as well as its 3-chlorobenzoic acid addition product (Equation 38) <1993CC577>. This reaction and that mentioned in Scheme 4 presumably proceed through initial oxidation at selenium followed by a Pummerer-type a-oxidation. Typical yields of the selenopyrans were relatively modest. The effect of base on this reaction was investigated however, it was not clear whether added base was really helpful in improving yields in the reaction. 

Problem 14.24 (a) Give the structural formula of the epoxide formed when w-chloroperoxybenzoic acid reacts with (i) cw-2-butene and (ii) tra 5-2-butene. (The epoxides are stereoisomers.) (b) What can you say about the stereochemistry of the epoxidation (c) Why is a carbocation not an intermediate ... 

The scope of peroxytrifluoroacetic acid oxidations resembles that of peroxyacetic acid and other peracids, although sometimes the outcome may be different [285]. The advantage of peroxytrifluoroacetic acid is that it reacts faster than the other peroxy acids peroxyacetic acid, peroxyben-zoic acid, w-chloroperoxybenzoic acid [286], and peroxyformic acid [285]. 

Whenever a chiral product is formed by reaction between achiral reagents, the product is racemic that is, both enantiomers of the product are formed in equal amounts. The epoxidation reaction of geraniol with w-chloroperoxybenzoic acid, for instance, gives a racemic mixture of (2R,3S) and (2S,3R) epoxides. 

Other reagents have been employed to oxidize aromatic aldehydes to arylformates these include peroxyacetic acid, peroxybenzoic acid , w-chloroperoxybenzoic acid (MCPBA) and organoperoxyseleninic acid. Sodium perborate and sodium carbonate have also been shown to be versatile activating reagents of hydrogen peroxide for similar transformations . 

Peroxy acids react with alkenes to give oxiranes. In the Prileschajew reaction, peroxybenzoic acid, w-chloroperoxybenzoic acid or monoperoxyphthalic acid is used. In weakly polar solvents, the reaction occurs in a concerted manner [5] ... 

Oxepan and other oxygen- or nitrogen-containing saturated heterocycles can be prepared in high yield by the dehydrative coupling of aamino-alcohols, using diethyl azodicarboxylate and triphenylphosphine. The synthetically useful oxepin-2,7-diones (muconic acid anhydrides) can be conveniently prepared by the oxidation of ortho-henzoquinones with w-chloroperoxybenzoic acid. °... 

The oxidation of thiadiazine 146 (R = Cl) with w-chloroperoxybenzoic acid or with dinitrogen tetroxide was unsuccessful, neither sulfoxide nor starting material being recovered. However, oxidation of the 3,5-dimorpholinothiadiazine 146 (R = 1-morpholino) with either oxidant gave excellent yields of sulfoxide 147 (Equation 18) <2000J(P1)1081>. 

More recently, Merritt and Olofsson reported a convenient modified procedure for the synthesis of phenylbenziodoxole 147 by a one-pot reaction of 2-iodobenzoic acid with w-chloroperoxybenzoic acid, triflu-oromethanesulfonic acid (TfOH) and benzene followed by addition of aqueous ammonia (Scheme 2.50) [284],... 

The most general reagents for conversion of simple alkenes to epoxides are peroxycarboxylic acids. w-Chloroperoxybenzoic acid (MCPBA) is a particularly convenient reagent, but it is not commercially available at the present time. The magnesium salt of monoperoxyphthalic acid has been recommended as a replacement. Potassium hydrogen peroxysulfate, which is sold commercially as oxone, is a convenient reagent for epoxidations that can be done in aqueous methanol. Peroxyacetic acid, peroxybenzoic acid, and peroxytrifluoroacetic acid have also been used frequently for epoxidation. All of the peroxycarboxylic acids are potentially hazardous materials and require appropriate precautions. 

Epoxidationof conjugated polyenes formed by thermal degradation of poly (vinyl chloride) (PVC) was carried out in cyclohexanone and tetrahydrofuran solution with w-chloroperoxybenzoic acid (mCPBA). PVC was thermally degraded in the solid state under continuous nitrogen flow at 200 °C for 30 min leading to 0.6 mol% double bonds in the polymer chain as determined from the UV-visible spectrum of... 

The amount of w-chloroperoxybenzoic acid consumed by a known weight of the sample can be used to calculate the concentration of antioxidant present. 

Syntheses of diastereoisomeric cyclic epoxyalcohols have been described, thus oxidation of the cyclohexenol (16) with p-nitroperoxybenzoic acid was stereoselective, whereas reduction of the corresponding epoxyketone gave the stereoisomer. In related work, a stereoselective synthesis of /rfl j-2,3-epoxycyclo-hexanol (19) was achieved in high yield by oxidizing the trimethylsilyl ether (18) with w-chloroperoxybenzoic acid, whereas the cw-isomer (17) had been obtained in 91 % yield by the oxidation of cyclohex-2-en-l-ol with the same oxidant. ... 

Conditions have been described for the selective oxidation of (Z,Z)cyclo-octa-2,4-dienol (21) to 9-oxabicyclo[3,3,l]non-3-ene-exo-2-oI (20) and a/i/i-2,3-epoxy-cyclo-oct-4-enol (22). With w-chloroperoxybenzoic acid at 0 °C, 91 % of (22) was obtained, but when t-butylhydroperoxide was used in the presence of vanadyl acetoacetonate, the other double bond was oxidized, and the oxiran was opened... 

A convenient high yield synthesis of 3-iodo-3-methylcephams (373) and 3-alkoxy-3-methylcephams is by reaction of the thiazoline azetidinone (372) with iodine or sulphenyi halides. Cooper first reported that (374), a degradation product of penicillin, gave a mixture of penicillin sulphoxide (376) and desacet-oxycephalosporin sulphoxide (377) when treated with /w-chloroperoxybenzoic acid in the presence of TFA, and this transformation was used in Kishi s biogenetic-type synthesis of penam and cephem derivatives- The results are not always... 

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