Selenium Dioxide

23 July, 2015 / by SK / in Reactions

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General Characteristics

Selenium dioxide oxidizes allylic C-H bonds, providing an option to synthesize allylic alcohols from alkenes. Even though SeO₂ is a toxic reagent, it is used frequently since it mediates a transformation that is hard to effect by other means. The reaction conditions are mild too.

When re-oxidants such as TBHP (tert-butyl hydroperoxide) are used, SeO₂ can be reduced to substoichiometric amounts.

General References

Riley, H. L.; Morley, J. F.; Friend, N. A .C. J. Chem. Soc. 1932, 1875.
Rabjohn, N. Org. React. 1949, 5, 331.
Rabjohn, N. Org. React. 1976, 24, 261.
Bulman Page, P. C.; McCarthy, T. J. Comprehensive Organic Synthesis 1991,7, 84, 108.

Reaction Mechanism

The reaction mechanism is generally explained by the ene reaction followed by [2,3]-sigmatropic rearrangement. (Ref: J. Org. Chem. 2000, 65, 7554., Tetrahedron Lett. 2003, 44, 1099.)

Examples

The total synthesis of vinblastine.^[1]

The total synthesis of resiniferatoxin.^[2]

The total synthesis of tetrodotoxin^[3]: Under the conditions using PhSeSePh/PhIO₂/Py (the Barton modification),^[4] the substrates are oxidized all the way to enones.

The α-position of carbonyl compounds is also susceptible to oxidation by SeO₂. Various oxidation products can be synthesized depending on the conditions.

Experimental Procedure

Allylic oxidation of geranyl sulfone.^[5]

Experimental Tips
References

[1] Fukuyama,T. et al. J. Am. Chem. Soc. 2002, 124, 2137. DOI: 10.1021/ja0177049 [2] Wender, P. A. et al. J. Am. Chem. Soc. 1997, 119, 12976. DOI: 10.1021/ja972279y [3] Hinman, A.; Du Bois, J. J. Am. Chem. Soc. 2003, 125, 11510. DOI: 10.1021/ja0368305 [4] Barton, D. H. R.; Crich, D. Tetrahedron 1985, 41, 4395. doi:10.1016/S0040-4020(01)97207-2 [5] Marshall, J. A.; Andrews, R. C. J. Org. Chem. 1985, 50, 1602. DOI: 10.1021/jo00210a009