3-Chloroperoxybenzoic acid

Three peroxyacids are produced commercially for the merchant market peroxyacetic acid as a 40 wt % solution in acetic acid, y -chloroperoxybenzoic acid, and magnesium monoperoxyphthalate hexahydrate. Other peroxyacids are produced for captive use, eg, peroxyformic acid generated in situ as an epoxidizing agent. 

The ratio of yy -epoxide (shown above) to ant -eipoxide is 10—25 1 with TYZORTPT catalysis, whereas vanadjdacetylacetonate is less selective and y -chloroperoxybenzoic acid gives the reverse 1 25 ratio. It is supposed that TYZOR TPT esterifies the free hydroxyl, then coordinates with the peroxide to favor yy -epoxidation (135). This procedure is related to that for enantioselective epoxidation of other allyflc alcohols in 9—95% enantiomeric excess (135). 

The nonfluonnated double bond m 3-perfluoroalkyl-l-propene is epoxidized with difficulty by ni-chloroperoxybenzoic acid [20] (equation 12)... 

Oxidation oi S-fluoro-t,3-dimethyluraciI by m-chloroperoxybenzoic acid leads to 4-hydroxy-l,3-dimethylimidazoledione m-chlorobenzoate [80] (equadon 72). 

Fluoro-2,2-dinitroethylamine is oxidized by m-chloroperoxybenzoic acid 10 the corresponding hydroxylamine, which, on further oxidation by a second equivalent of the peroxyadd or bromine, gives an oxime [85] (equation 77)... 

Conjugated 1,3-diazadienes are oxidized by m-chloroperoxybenzoic acid to I-oxa-2,4-diazoles [SS] (equation 80)... 

Oxidation of more lipophihc pentafluorophenyl sulfamimine to the corresponding sulfamyloxaziridine by m-chloroperoxybenzoic acid gives better yields in a shorter tune compared with the nonfluonnated analogue [95] (equation 87)... 

Trifluoromethanesulfinyl chloride is prepared by oxidation of trifluorometh-anesulfenyl chloride with m chloroperoxybenzoic acid in high yield [110] (equa tion 101)... 

Perfluoro(tetramethylene) sulfiUmine is easily oxidized to a sulfoximme by m-chloroperoxybenzoic acid [773] (equation 103)... 

It is possible to introduce this group selectively onto a primary alcohol in the presence of a secondary alcohol. The derivative is stable to KMn04, m-chloroperoxybenzoic acid, LiAlH4, and Cr03-Pyr. Since this derivative is similar to the p-methoxyphenyl ether, it should also be possible to remove it oxidatively. The GUM ethers are less stable than the MEM ethers in acid, but have comparable stability to the SEM ethers. It is possible to remove the GUM ether in the presence of a MEM ether. 

Alkenes are oxidized to give epoxides on treatment with a peroxyacid (RCO H), such as mefn-chloroperoxybenzoic acid. An epoxide, also called an oxirane, is a cyclic ether with an oxygen atom in a three-membered ring. For example ... 

Name the following alkenes( and predict the products of their reaction with (i) Twta-chloroperoxybenzoic acid, (ii) KMn04 in aqueous acid, and (iii) O3, followed by Zn in acetic acid ... 

In the laboratory, as we saw in Section 7.8, epoxides are prepared by treatment of an alkene with a peroxyacid (RC03H), typically m-chloroperoxybenzoic acid. 

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 m-chloroperoxybenzoic acid, for instance, gives a racemic mixture of (2R,3S) and (2S,3R) epoxides. 

Thermolysis (115°C) or irradiation of the epoxide 3, generated from bicyclo[2.2.0]hexa-2,5-diene ( Dewar benzene") with 3-chloroperoxybenzoic acid, gives a mixture of the valence tautomers oxcpin and benzene oxide together with traces of phenol.111112... 

In contrast to the attempts with 3-benzothiepins, furo[3,4-r/]thiepin is readily oxidized with 3-chloroperoxybenzoic acid to the corresponding S-oxide and S, 5-dioxide, which have been characterized by H NMR and UV spectra.71... 

Benzothiepins 13 and their 2,3-dihydro precursors 12 can be oxidized by two equivalents of 3-chloroperoxybenzoic acid to afford the sulfones 15 and 14, respectively, in moderate to good yields.2,9 83 Sulfones 15 can be prepared using two routes, the reverse order (oxidation, followed by elimination) also being possible (see Section 2.1.2.1. for a description of the elimination reactions). The preferred route must be decided for individual cases. 

Benzothiepin 1-oxides 17, stabilized by electron-withdrawing groups, are available from the 1 -benzothiepins in good yields when only one equivalent of 3-chloroperoxybenzoic acid is used. 

The resulting sulfoxides 17 can be further oxidized by a second equivalent of 3-chloroperoxybenzoic acid to afford the sulfones 18, also in good yields.14 In general, however, the direct synthesis of the sulfones with two equivalents of 3-chloroperoxybenzoic acid affords better yields. 

In the same manner, the S-monoxidized iron complex can be oxidized with a second equivalent of 3-chloroperoxybenzoic acid and subsequent irradiation to give the stable 1-benzothiepin 1,1-dioxide in 76% yield.23 (For removal of the iron ligand, see also Section 2.2.1.). 

Treatment of ethyl 2,7-di-/ert-butylthiepin-4-carboxylate (24) with 3-chloroperoxybenzoic acid at — 78 °C results in the benzene derivative 25 only, and no sulfur-oxidized products 80 however, the stable 2,7-di-ter/-butylthiepin (26) can be oxidized with 0-benzyl 00-hydrogen monoper-oxycarbonate at — 78 °C to give the corresponding S-oxide 27, which was monitored by HNMR spectroscopy at — 40°C. At —15 C, sulfoxide 27 was converted, via extrusion of sulfur monoxide, with a half-life of 5.5 hours to the benzene derivative 28.87 The oxidation reaction of 26 with excess of the monoperoxycarbonate did not proceed to the S,S-dioxide, even though the parent thiepin 1,1-dioxide is known to be stable at room temperature.15... 

There are no examples of monocyclic azepine JV-oxides however, cyclopent 7>]azcpine is readily oxidized by 3-chloroperoxybenzoic acid at room temperature to give the moderately stable, green, crystalline cyclopent[6]azepine 1-oxide (l).2 6,8-Dibromocyclopcnt[6]azcpinc, under similar conditions, fails to react. 

Benzazepines 1 are oxidized to their 7V-oxides 2 by 3-chloroperoxybenzoic acid (1 equivalent) at room temperature.78 1 78 However, at higher temperatures, and with an excess of oxidant,178 or with a stronger peracid.78 N-oxide formation is accompanied by epoxidation at C4-C5 (see Section 3.2.2.2.I.). 

Dialkyl-5//-dibenz[/>,/]azepines 6 on oxidation with 3-chloroperoxybenzoic acid undergo ring contraction to 9,10-dihydroacridinc-9-carbaldehydes 7.223 In contrast, 5,10,11-trialkyl derivatives 8 yield mixtures of the acridinyl ketones 9 and 10,11-epoxides 10. 

Reduction of the 1//-1,2-benzodiazepines 6 with lithium aluminum hydride results in the dihydro compounds 8, which are dehydrogenated to the 3H-1,2-benzodiazepines 9 by 4-phenyl-4//-l,2,4-triazole-3,5-dione.123 The products readily revert to the 1//-tautomers in the presence of sodium methoxide. 3//-1,2-Benzodiazepines react with 3-chloroperoxybenzoic acid to give mixtures of 1- and 2-oxides, 10 and 11, in which the latter predominate. Treatment of the 2-oxides 11 with nucleophiles provides 3-substituted H- 1.2-benzodiazepines 12. Selected examples are given.124... 

Oxidation of benzodiazepinone 1 with 3-chloroperoxybenzoic acid gives a mixture of the oxaziridine 2 (10%) and the benzodiazepinone 4-oxidc 3 (40%).165... 

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