Iron(III) Acetylacetonate-Hydrogen Peroxide1


[14024-18-1]  · C15H21FeO6  · Iron(III) Acetylacetonate-Hydrogen Peroxide  · (MW 353.21) (H2O2)

[7722-84-1]  · H2O2  · Iron(III) Acetylacetonate-Hydrogen Peroxide  · (MW 34.02)

(b-epoxidation of cholesterol derivatives;2 trans-epoxidation of alkenes3)

Alternate Name: tris(acetylacetonate)iron(III)-hydrogen peroxide.

Physical Data: Fe(acac)3: mp 184 °C, d 1.33 g cm-3.

Solubility: slightly sol cold and hot water; sol alcohol, acetone, benzene, chloroform.

Form Supplied in: dark red powder; widely available.

Preparative Method: reagent combination is generated in situ, via dropwise addition of 30% Hydrogen Peroxide (49 mmol) to a stirred solution of Tris(acetylacetonato)iron(III) (2.7 mmol), and substrate (0.26 mmol) in acetonitrile.2,3

Handling, Storage, and Precautions: use in a fume hood. Fe(acac)3 causes severe eye irritation and may cause skin irritation. Toxic fumes of carbon monoxide and carbon dioxide are generated on decomposition. It is incompatible with strong oxidizing agents; thus the H2O2 has to be used in excess because it is decomposed by FeIII ion.4 Reactions should be worked up by decomposition of excess H2O2 with saturated aqueous sodium sulfite and then extraction of product with ether. See also Hydrogen Peroxide.

b-Epoxidation of Cholesterol Derivatives.2

Steroidal alkenes are stereoselectively epoxidized from the b-face with Fe(acac)3-H2O2 (eq 1), via a radical process.5 In contrast, organic peracids (m-Chloroperbenzoic Acid) yield the a-epoxide via attack from the least hindered face.6 Cholest-4-en-3b-ol yields b-epoxidation with Fe(acac)3 and organic peracids, but this is due to hydroxyl coordination. Other cholest-4-ene derivatives yield b-epoxidation with Fe(acac)3 and a-epoxidation with organic peracids (eq 2).2 Low yields of epoxide with some substrates are usually caused by formation of the allylic oxidation product, and indeed use of Fe(acac)3-t-Butyl Hydroperoxide or other transition metal acac salts yield predominantly allylic oxidation.5a

trans-Epoxidation of Alkenes.3

trans-Epoxide is obtained selectively in the Fe(acac)3.H2O2 mediated oxidation of both cis and trans alkenes (eq 3).3 This contrasts with m-CPBA oxidation in which alkene geometry is conserved.7

1. Meunier, B. BSF(2) 1983, 345 (CA 1984, 101, 89 882p).
2. Tohma, M.; Tomita, T.; Kimura, M. TL 1973, 44, 4359.
3. Yamamoto, T.; Kimura, M. CC 1977, 948.
4. Yamamoto, H.; Takei, H.; Yamamoto, T.; Kimura, M. CPB 1979, 27, 789.
5. (a) Kimura, M.; Muto, T. CPB 1981, 29, 35. (b) Kimura, M.; Muto, T. CPB 1981, 29, 1862.
6. Kirk, D. N.; Hartshorn, M. P. Steroid Reaction Mechanisms; Elsevier: New York, 1968; p 71.
7. Berti, G.; Top. Stereochem. 1973, 7, 93.

Andrew D. White

Parke-Davis Pharmaceutical Research, Ann Arbor, MI, USA

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