- Sharpless epoxidation
The Sharpless epoxidation reaction is an enantioselective
chemical reaction to prepare 2,3-epoxyalcohols from primary and secondary allylic alcohols. [Katsuki, T.; Sharpless, K. B. "J. Am. Chem. Soc. " 1980, "102", 5974. (DOI|10.1021/ja00538a077)] [Hill, J. G.; Sharpless, K. B.; Exon, C. M.; Regenye, R. "Org. Syn. ", Coll. Vol. 7, p.461 (1990); Vol. 63, p.66 (1985). ( [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv7p0461 Article] )] This reaction gives good yields and enantioselectivities over a broad range of substrates.The oxidizing agent is t-butylperoxide. Enantioselectivity is achieved by a catalyst formed from titanium tetra(isopropoxide) and
diethyl tartrate . Only 5-10 mol% of the catalyst in the presence of 3Åmolecular sieve s (3Å MS) is necessary. [Gao, Y.; Hanson, R. M.; Klunder, J. M.; Ko, S. Y.; Masamune, H.; Sharpless, K. B. "J. Am. Chem. Soc. " 1987, "109", 5765-5780. (DOI|10.1021/ja00253a032)]Several reviews have been published. [Johnson, R. A.; Sharpless, K. B. "Comp. Org. Syn." 1991, "7", 389-436. (Review)] [Hüft, E. "Top. Curr. Chem." 1993, "164", 63-77. (Review)] [Katsuki, T.; Martin, V. S. "Org. React." 1996, "48", 1-300. (Review)] [Pfenninger, A. "Synthesis" 1986, 89-116. (Review)]
Epoxides can be easily converted into dialcohols, aminoalcohols or
ether s, so formation of chiral epoxides is a very important step in the synthesis of natural products.K. Barry Sharpless shared theNobel prize in 2001 for his work on asymmetric oxidations.The prize was shared withWilliam S. Knowles andRyoji Noyori .Reaction mechanism
The Sharpless group has investigated both the reaction kinetics [Woodard, S. S.; Finn, M. G.; Sharpless, K. B. "
J. Am. Chem. Soc. " 1991, "113", 106-113. (DOI|10.1021/ja00001a018)] and the structure of the catalyst [Finn, M. G.; Sharpless, K. B. "J. Am. Chem. Soc. " 1991, "113", 113-126. (DOI|10.1021/ja00001a019)] .ee also
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Asymmetric catalytic oxidation References
External links
* [http://www.chem.harvard.edu/groups/myers/handouts/16_Sharpless_Asymmetric_E.pdf Sharpless Asymmetric Epoxidation Reaction]
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