Tamao-Fleming Oxidation

• General Characteristics

Organosilicon compounds containing hetero atom substituent(s) on the silicon atom are oxidized by hydrogen peroxide in the presence of a fluoride source and a weak base. The reaction is known as the Tamao-Fleming oxidation and involves the migration of alkyl groups that leads to the formation of alcohol products. The reaction proceeds under very mild conditions.

The stereochemistry of the carbon bonded to the silicon is retained.

• General References

・Tamao, K.; Akita, M.; Kumada, M.Organometallics 1983, 2, 1694. DOI: 10.1021/om50005a041
・Tamao, K.; Kakui, T.; Akita, M.; Iwahara, T.; Kanatani, R.; Yoshida, J.; Kumada, M. Tetrahedron 1983, 39, 983. doi:10.1016/S0040-4020(01)88597-5
・Fleming, I.; Henning, R.; Plaut, H. J. Chem. Soc., Chem. Commun. 1984, 29. DOI: 10.1039/C39840000029
・Fleming, I.; Henning, R.; Parker, D.C.; Plaut, H.; Sanderson, P.E.J. J. Chem. Soc., Perkin Trans. 1 1995, 317. doi:10.1039/P19950000317
・Review: Jones, G. R.; Landais, Y. Tetrahedron 1996, 52, 7599. DOI: 10.1016/S0040-4020(96)00038-5
・総説: 玉尾皓平, 有機合成化学協会誌, 1988, 46, 861.
・Tamao, K. Org. Synth. 1994, 73, 94.

• Reaction Mechanism

The reaction is thought to proceed via hypervalent silicate intermediates with retention of configuration during the alkyl migration. (J. Am. Chem. Soc. 2001, 123, 1970.)

• Examples

The Tamao-Fleming reaction is useful to synthesize anti-Markovnikov alcohols when combined with olefin hydrosilylation. The intramolecular hydrosilylation is effective to synthesize alcohols that are difficult to obtain by intermolecular hydroboration, as the two reactions show complementary stereoselectivity. It is especially useful in the synthesis of polyol compounds.^[1]

Nucleophilic hydroxymethylation^[2]: Reacting silylmethyl Grignard reagents with aldehydes, ketones, or alkyl halides followed by the Tamao-Fleming oxidation gives the corresponding hydroxymethylated products.

The 1,4-addition of silicon nucleophiles followed by the Tamao oxidation gives β-hydroxycarbonyl (aldol) compounds. Here is an example in which the tandem Michael-aldol reaction is followed by the conversion of Si into O.^[3]

• Experimental Procedure

• Experimental Tips

• References

[1] Tamao, K. et al. J. Am. Chem. Soc. 1986, 108, 6090. DOI: 10.1021/ja00279a097
[2] Tamao, K. et al. Org. Synth. 1990, 69, 96.
[3] Williams, D. J. et al. J. Org. Chem. 1999, 64, 6005. DOI: 10.1021/jo9905672

• Related Books

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[amazonjs asin=”0471196584″ locale=”US” title=”Silicon in Organic, Organometallic, and Polymer Chemistry”]

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oxidation of silanes, synthesis of alcohols