Introduction
meta-Chloroperoxybenzoic acid (m-CPBA) is a white crystalline powder with a melting point of 90 °С. In pure form, it can be detonated by shock or by sparks, and therefore it is stored as a mixture containing less than 72% m-CPBA (containing water and meta-chlorobenzoic acid). It is soluble in dichloromethane, chloroform, ethyl acetate, alcohol, and insoluble in hexanes, carbon tetrachloride, and water. m-СРВА is obtained by the reaction of m-chlorobenzoyl chloride with a basic solution of hydrogen peroxide in the presence of MgSO4
.7H2O. m-CPBA is used as oxidizing agent in Baeyer–Villiger oxidations[1] and in the synthesis of epoxides,[2], oxaziridines,[3] α-disulfines, [4] sulfoxides and sulfones,[5] N-oxides,[6] and ketones.[7]
Table 1 Use of m-CPBA
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(A) Troisi and co-workers developed a new synthetic pathway to sulfonamidic azobenzene derivatives 2 based on the oxidation of 2,3-dihydrobenzothiadiazines 1 with m-CPBA. It was shown that high yields were achieved when three equivalents of the peroxyacid were used.[8]
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(B) Recently, Kitamura et al. found that oxidative fluorination of 1,3-dicarbonyl compounds 3 with hydrofluoric acid is efficiently performed with the use of stoichiometric amounts of m-CPBA. It is worth noting that a catalytic amount of iodoarene is needed for the reaction to proceed.[9]
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(C) Bovenkerk and Esser showed that the oxidation of different benzo[c]furans 5 with m-CPBA afforded diketones 6, that were used as precursors for 2-aniline-substituted isoindoles.[10]
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(D) Nitroso esters 8, which are attractive monomers for synthesis of different polymers with high molecular weight and regular monomer sequence, were obtained by the reaction of 4,4-dimethyl-2-oxazolines 7 with two equivalents of m-CPBA. Monomers with a similar structure may be obtained when 4,4-dimethyl dihydro-1,3-oxazines are used as starting materials.[11]
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(E) The double oxylactonization of 9 in the presence of m-CPBA and dimethyl 2,2′-((2-iodo-1,3-phenylene)bis(oxy))(2S,2′S)-dipropionate as a catalyst was a key step in total synthesis of a monocerin derivative 10, a potentially biologically active compound. The stereochemistry is controlled by an iodoarene catalyst.[12]
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(F) Rodríguez and Moran studied an interesting oxidative rearrangement of tertiary propargylic alcohols 11 to enoic acids 12 in the presence of m-CPBA. They suggested that the reaction proceeds by hydrogen-bond directed alkyne epoxidation followed by 1,2-aryl migration.[13]
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