Oxone, Potassium peroxomonosulfate
The composition of the oxidizing agent Oxone® is 2KHSO5.KHSO4.K2SO4. The active component potassium monopersulfate (KHSO5, potassium peroxomonosulfate) is a salt from the Caro´s acid H2SO5.
The use of Oxone has increased rapidly. Reasons for this are the stability, the simple handling, the non-toxic nature, the versatility of the reagent and the low costs.
B. R. Travis, M. Sivakumar, G. O. Hollist, B. Borhan, Org. Lett., 2003, 5, 1031-1034. DOI
As long as Oxone is stored under dry and cool conditions, it loses about 1% activity per month under release of oxygen and heat. Decomposition to SO2 and SO3 takes place under the influence of heat (starting at 300°C).
Acidic, aqueous solutions of the pure reagent in distilled water are relatively stable. The stability reaches a minimum at pH 9, where the mono anion (HSO5-) has the same concentration as the dianion (SO52-). Iron, cobalt, nickel, copper, manganese and further transition metals can catalyze the decay of Oxone in solution.
The following secondary reactions should be avoided: Halides can be oxidized to halogens (e.g. chloride to chlorine), cyanides react with Oxone under release of hydrogen cyanide, "heavy" transition metals (Cu, Mn, Co, Ni) and their salts lead to the decomposition of Oxone under release of oxygen.
Highly efficient, mild, and simple protocols allow the oxidation of aldehydes to carboxylic acids and esters utilizing Oxone as the sole oxidant. These reactions may prove to be valuable alternatives to traditional metal-mediated oxidations.
B. R. Travis, M. Sivakumar, G. O. Hollist, B. Borhan, Org. Lett., 2003, 5, 1031-1034.
2-Iodoxybenzenesulfonic acid, which can be generated in situ from 2-iodobenzenesulfonic acid sodium salt, is a much more active catalyst than modified IBXs for the oxidation of alcohols with Oxone. Highly efficient and selective methods for the oxidation of alcohols to carbonyl compounds such as aldehydes, carboxylic acids, and ketones were established.
M. Uyanik, M. Akakura, K. Ishihara, J. Am. Chem. Soc., 2009, 131, 251-262.
A novel, metal-free oxidation system for the catalytic synthesis of aldehydes and ketones using TEMPO and a quarternary ammonium salt as catalysts and Oxone as oxidant proved especially successful for the synthesis of ketones. The mild conditions tolerate even sensitive silyl protective groups which can otherwise be cleaved in the presence of Oxone.
C. Bolm, A. S. Magnus, J. P. Hildebrand, Org. Lett., 2000, 2, 1173-1175.
Catalytic use of o-iodoxybenzoic acid (IBX) in the presence of Oxone as a co-oxidant is demonstrated for the oxidation of primary and secondary alcohols. In addition, the in situ oxidation of 2-iodosobenzoic acid (IBA) and even commercially available 2-iodobenzoic acid (2IBAcid) by Oxone to IBX allows the use of these less hazardous reagents, in place of potentially explosive IBX, as catalytic oxidants.
A. P. Thottumkara, M. S. Bowsher, T. K. Vinod, Org. Lett., 2005, 7, 2933-2936.
The presence of KBr enabled a direct benzylic oxidation of alkylarenes via C-H bond abstraction using oxone as oxidant under mild conditions. This reaction proceeded with excellent selectivity by thermal oxidation or photooxidation to provide a broad range of aryl ketones in high yields.
K. Moriyama, M. Takemura, H. Togo, Org. Lett., 2012, 14, 2414-2417.
Oxidation of alkyl aryl ketones in the presence of Oxone, trifluoroacetic anhydride and a catalytic amount of iodobenzene affords α-hydroxyalkyl aryl ketones in good yield. This method provides an effective and economical entry for the α-hydroxylation of ketones.
C. Chen, X. Feng, G. Zhang, Q. Zhao, G. Huang, Synthesis, 2008, 3205-3208.
Specific oxidation protocols have been developed for the cleavage of styrenes, aliphatic olefins, and terminal aliphatic olefins to carbonyl compounds with ruthenium trichloride as catalyst. Olefins that are not fully substituted are converted to aldehydes rather than carboxylic acids.
D. Yang, C. Zhang, J. Org. Chem., 2001, 66, 4814-4818.
The OsO4-catalyzed direct oxidation of olefins via the carbon-carbon cleavage of an osmate ester by the action of oxone allows the preparation of ketones or carboxylic acids in high yields. This method should be applicable as an alternative to ozonolysis.
B. R. Travis, R. S. Narayan, B. Borhan, J. Am. Chem. Soc., 2002, 124, 3824-3825.
A new mild RuO4-catalyzed ketohydroxylation of olefins is reported. α-Hydroxy ketones were obtained with high regioselectivity and in good to excellent yields.
B. Plietker, J. Org. Chem., 2003, 68, 7123-7125.
Transformation of epoxides to β-alkoxy alcohols, acetonides, and α-alkoxy ketones is achieved by using molybdenum(VI) dichloride dioxide (MoO2Cl2) as a catalyst. Alcohol, aldehyde, oxime, tosyl, and tert-butyldimethylsilyl functional groups are tolerated during the methanolysis and acetonidation of the functionalized epoxides.
K. Jeyakumar, D. K. Chand, Synthesis, 2008, 807-819.
Grubbs' 2nd generation metathesis catalyst can be used in tandem olefin metathesis/oxidation protocols. These ruthenium-catalyzed processes provide access to cis-diols or α-hydroxy ketones from simple olefinic starting materials.
A. A. Scholte, M. H. An, M. L. Snapper, Org. Lett., 2006, 8, 4759-4762.
A mild and convenient oxidative Nef reaction using Oxone is described. Following this procedure primary and secondary nitroalkanes generates carboxylic acids and ketones, respectively, both in good yields.
P. Ceccherelli, M. Curini, M. C. Marcotullino, F. Epifano, O. Rosati, Synth. Commun., 1998, 28, 3057-3064.
The use of Oxone allows the conversion of various aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates into the corresponding oxidized products in excellent yields. This method tolerates a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific.
G. A. Molander, L. N. Cavalcanti, J. Org. Chem., 2011, 76, 623-630.
A two-step sequence of asymmetric dihydroxylation and regioselective monooxidation gave enantiopure α-hydroxy ketones (acyloins). The combination of RuCl3/Oxone/NaHCO3 was used in the first catalytic regioselective oxidation of vic-diols to α-ketols.
B. Plietker, Org. Lett., 2004, 6, 289-291.
An efficient method for the oxidative cleavage of internal and terminal alkynes to carboxylic acids using a combination of RuO2/Oxone/NaHCO3 in a CH3CN/H2O/EtOAc solvent system is described. Various alkynes, regardless of their electron density, were oxidized to carboxylic acids in excellent yield.
D. Yang, F. Chen, Z.-M. Dong, D.-W. Zhang, J. Org. Chem., 2004, 69, 209-212.
A simple, efficient and mild method for the selective bromination of activated aromatic compounds using ammonium bromide as the source of bromine and Oxone as the oxidant in methanol or water as solvent proceeds at ambient temperature in good yields without a catalyst.
M. A. Kumar, C. N. Rohitha, S. J. Kulkarni, N. Narender, Synthesis, 2010, 1629-1632.
Hofmann rearrangement of carboxamides to carbamates using Oxone as an oxidant can be efficiently catalyzed by iodobenzene via hypervalent iodine species generated in situ in the presence of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) in aqueous methanol solutions. Under these conditions, Hofmann rearrangement of various carboxamides affords corresponding carbamates in high yields.
A. Yoshimura, K. R. Middleton, M. W. Luedtke, C. Zhu, V. V. Zhdankin, J. Org. Chem., 2012, 77, 11399-11404.
Alkylcarboxamides can be converted to the respective alkylcarbamates by Hofmann rearrangement using hypervalent iodine species generated in situ from PhI and Oxone in methanol. In addition, substituted benzamides can be converted to the respective quinone derivatives by treatment with Oxone and iodobenzene in aqueous acetonitrile.
A. A. Zagulyaeva, C. T. Banek, M. S. Yusubov, V. V. Zhdankin, Org. Lett., 2010, 12, 4644-4647.
Iodocyclization of unsaturated tosylamides promoted by Oxone oxidation of KI afforded, in good yields, N-tosyl iodopyrrolidines and piperidines.
M. C. Marcotullio, V. Campagna, S. Sternativo, F. Costantino, M. Curini, Synthesis, 2006, 2760-2766.
The oxidative intramolecular bromo-amination of various N-alkenyl sulfonamides and N-alkenoxyl sulfonamides via umpolung of alkali metal bromides occurred exo-selectively to generate pyrrolidines and isoxazolidines in high yields with good diastereoselectivities. This method provided the desired products with a low amount of organic waste.
K. Moriyama, Y. Izumisawa, H. Togo, J. Org. Chem., 2011, 76, 7249-7255.
A general, efficient and metal-free protocol for the direct oxidation of secondary amines to nitrones tolerates other functional groups or existing stereogenic centers using Oxone in a biphasic basic medium as the sole oxidant.
C. Gella, È. Ferrer, R. Alibés, F. Busqué, P. de March, M. Figueredo, J. Font, J. Org. Chem., 2009, 74, 6365-6367.
Addition of oxone to a mixture of a 1,2-phenylenediamine and an aldehyde in wet DMF results in rapid formation of benzimidazoles under very mild conditions. Products are isolated in high purity in most cases by simple aqueous precipitation. The reaction is applicable to a wide range of substrates but does not allow the conversion of aldehydes that are sensitive to oxone under acidic reaction conditions.
P. L. Beaulieu, B. Haché, E. von Moos, Synthesis, 2003, 1683-1692.
A Cu(II)-catalyzed acylation of acyloins with a thiol ester present in Wittig reagents under neutral conditions through a push-pull mechanism enables a one-pot lactonization to yield butenolides. The synthetic utility of this method for the synthesis of natural products is shown.
K. Matuso, M. Shindo, Org. Lett., 2010, 12, 5346-5349.
α-Bromo- or α-chloro-α,β-unsaturated carbonyl compounds were prepared in good yields by addition of hydrobromic acid or hydrochloric acid to α,β-unsaturated carbonyl compounds in the presence of Oxone in CH2Cl2 followed by treatment of the resulting dihalides with Et3N.
K.-M. Kim, I.-H. Park, Synthesis, 2004, 2641-2644.
The use of oxone in trifluoroacetic acid enables a general and convenient synthesis of [bis(trifluoroacetoxy)iodo]arenes at room temperature. The oxidation of perfluoroalkyl iodides gives [bis(trifluoroacetoxy)iodo]perfluoroalkanes, that can be converted to stable [hydroxy(tosyloxy)iodo]perfluoroalkanes.
A. A. Zagulyaeva, M. S. Yusubov, V. V. Zhdankin, J. Org. Chem., 2010, 75, 2119-2122.
An oxidative desulfurization approach enables the construction of oxadiazole and thiadiazole heterocycles in the presence of iodobenzene and Oxone. The use of iodobenzene and the inexpensive readily available oxidant Oxone makes the reaction system simple and versatile for desulfurization.
K. N. Patel, N. C. Jadhav, P. B. Jagadhane, V. N. Telvekar, Synlett, 2012, 23, 1970-1972.