Tetraethylammonium Periodate


[5492-69-3]  · C8H20INO4  · Tetraethylammonium Periodate  · (MW 321.19)

(oxidizing agent used for generating nitroso compounds from hydroxamic acids,1 N-hydroxycarbamic esters,2 and N-hydroxyureas3)

Physical Data: mp 176-177 °C.

Solubility: sol H2O, MeCO2H, acetone, pyridine, CH2Cl2; slightly sol alcohol; insol ethyl acetate, Et2O, benzene.

Preparative Methods: a solution of periodic acid (H5IO6) (7.72 g, 0.034 mol) in water (20 mL) was added slowly to a cooled solution of 25% tetraethylammonium hydroxide (20 mL, 0.034 mol). The resulting solution was evaporated under reduced pressure, the solid residue was extracted with hot t-butyl alcohol, and the product was precipitated by addition of diisopropyl ether. Recrystallization from t-butyl alcohol yielded a white solid (8.5 g, 82%).4a Caution: a safety shield should be used since any excess H5IO6 present may explode violently during concentration of the aqueous solution and extraction of the crude salt.4b

Handling, Storage, and Precautions: the reagent is stable and is best stored in a desiccator in the dark.

Oxidizing Agent.

Tetraethylammonium periodate has similar oxidizing properties to Sodium Periodate but has the advantage that reactions can be conducted in nonaqueous media and its greater solubility in water may be useful in cases where the use of relatively less soluble periodate salts is problematic.4 Tetraethylammonium periodate has been used mainly for the oxidation of derivatives of hydroxylamines to yield nitroso compounds. It has been reported4 that stable nitroso compounds have been obtained from the oxidation of N-t-alkylhydroxylamines. Tetraethylammonium periodate was found to be a mild oxidant for the selective oxidation of hydroxamic acids,1 N-hydroxycarbamic esters,2 and N-hydroxy ureas3 in the presence of conjugated dienes (eqs 1-3). The highly reactive nitroso intermediates that were formed readily undergo Diels-Alder cycloaddition to the dienes to give synthetically useful cycloadducts. Further, it was demonstrated5 that cycloadducts of type (1) serve as a good source of highly reactive, transient nitroso species; they undergo facile retro-Diels-Alder reactions on heating to regenerate the nitroso intermediate and 9,10-dimethylanthracene. This method for the regeneration of the nitroso compound has been exploited in inter- and intramolecular nitroso-ene reactions.5

The generation of nitroso intermediates and trapping of these species by conjugated dienes has found application in natural product synthesis.6,7 For example, in the stereospecific synthesis of tabtoxin,6 the key stereochemical defining step involved the cycloaddition of benzyl nitrosoformate, generated in situ by Et4NIO4 oxidation of benzyl N-hydroxycarbamate, with ethyl 1,3-cyclohexadienecarboxylate (eq 4).

1. (a) Kirby, G. W.; Sweeny, J. G. JCS(P1) 1981, 3250. (b) Corrie, J. E. T.; Kirby, G. W.; Mackinnon, J. W. M. JCS(P1) 1985, 883.
2. Kirby, G. W.; McGuigan, H.; Mackinnon, J. W. M.; McLean, D.; Sharma, R. P. JCS(P1) 1985, 1437.
3. Christie, C. C.; Kirby, G. W.; McGuigan, H.; Mackinnon, J. W. M. JCS(P1) 1985, 2469.
4. (a) Qureshi, A. K.; Sklarz, B. JCS(C) 1966, 412. (b) Rowe, J. E.; Ward, A. D. AJC 1968, 21, 2761.
5. (a) Kirby, G. W.; McGuigan, H.; McLean, D. JCS(P1) 1985, 1961. (b) Keck, G. E.; Webb, R. R.; Yates, J. B. T 1981, 37, 4007.
6. Baldwin, J. E.; Bailey, P. D.; Gallacher, G.; Singleton, K. A.; Wallace, P. M. CC 1983, 1049.
7. (a) Miller, A.; Paterson, T. McC.; Procter, G. SL 1989, 1, 32. (b) Morley, A. D.; Hollinshead, D. M.; Procter, G. TL 1990, 31, 1047.

Andrew G. Wee & Jason Slobodian

University of Regina, Saskatchewan, Canada

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