Sharpless epoxidationNamed afterKarl Barry SharplessReaction typeRing forming reactionIdentifiersOrganic Chemistry Portalsharpless-epoxidationRSC ontology IDRXNO:0000141
The Sharpless epoxidation reaction is an enantioselective chemical reaction to prepare 2,3-epoxyalcohols from primary and secondary allylic alcohols.[1][2]
The stereochemistry of the resulting epoxide is determined by the diastereomer of the chiral tartrate diester (usually diethyl tartrate or diisopropyl tartrate) employed in the reaction. The oxidizing agent is tert-butyl hydroperoxide. 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]
The success of the Sharpless epoxidation can be attributed to five major aspects. First, epoxides can be easily converted into diols, aminoalcohols, and ethers, so formation of chiral epoxides is important in the synthesis of natural products. Second, substrate scope is large, includin many primary and secondary allylic alcohols. Third, the products of the Sharpless epoxidation frequently have enantiomeric excessesabove 90%. Fourth, the products of the Sharpless epoxidation are predictable. Finally, the reactants for the Sharpless epoxidation are commercially available and relatively inexpensive.[4]
K. Barry Sharpless shared the 2001 Nobel Prize in Chemistry for his work on asymmetric oxidations. The prize was shared with William S. Knowles and Ryōji Noyori.
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