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Sharpless epoxidation
Introduction
The Sharpless epoxidation reaction is an enantioselective chemical reaction to prepare 2,3-epoxyalcohols from primary and secondary allylic alcohols.[1][2] 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 3Å molecular sieves (3Å MS) is necessary.[3]
Several reviews have been published.[4][5][6][7]
Epoxides can be easily converted into dialcohols, aminoalcohols or ethers, so formation of chiral epoxides is a very important step in the synthesis of natural products. K. Barry Sharpless shared the Nobel prize in 2001 for his work on asymmetric oxidations. The prize was shared with William S. Knowles and Ryoji Noyori.
Reaction mechanism
Reaction mechanism
The Sharpless group has investigated both the reaction kinetics[8] and the structure of the catalyst[9].
References
References
- ↑ 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). (Article)
- ↑ 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)
- ↑ 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)
- ↑ Woodard, S. S.; Finn, M. G.; Sharpless, K. B. J. Am. Chem. Soc. 1991, 113, 106-113. (doi:10.1021/ja00001a018)
- ↑ Finn, M. G.; Sharpless, K. B. J. Am. Chem. Soc. 1991, 113, 113-126. (doi:10.1021/ja00001a019)