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The Sharpless epoxidation is viable with a large range of primary and secondary alkenic alcohols. Furthermore, with the exception noted above, a given dialkyl tartrate will preferentially add to the same face independent of the substitution on the alkene.To demonstrate the synthetic utility of the Sharpless epoxidation, the Sharpless group created synthetic intermediates of various natural ...
The Kharasch–Sosnovsky reaction is a method that involves using a copper or cobalt salt as a catalyst to oxidize olefins at the allylic position, subsequently condensing a peroxy ester (e.g. tert-Butyl peroxybenzoate) or a peroxide resulting in the formation of allylic benzoates or alcohols via radical oxidation. [1]
The Jacobsen epoxidation, sometimes also referred to as Jacobsen-Katsuki epoxidation is a chemical reaction which allows enantioselective epoxidation of unfunctionalized alkyl- and aryl- substituted alkenes. [1] [2] [3] It is complementary to the Sharpless epoxidation (used to form epoxides from the double bond in allylic alcohols).
The groups of Y. Shi [23] and W. Adam [24] published another enantioselective variant of the Rubottom oxidation in 1998 using the Shi chiral ketone in the presence of oxone in a buffered system to furnish α-hydroxy ketones in high yield and high enantiomeric excess.
The epoxidation of allylic alcohols is a class of epoxidation reactions in organic chemistry. One implementation of this reaction is the Sharpless epoxidation . Early work showed that allylic alcohols give facial selectivity when using meta-chloroperoxybenzoic acid (m-CPBA) as an oxidant.
Carbonyl allylation has been employed in the synthesis of polyketide natural products and other oxygenated molecules with a contiguous array of stereocenters. For example, allylstannanation of a threose-derived aldehyde affords the macrolide antascomicin B, which structurally resembles FK506 and rapamycin, and is a potent binder of FKBP12. [12]
The Sharpless epoxidation is an example of an enantioselective process, in which an achiral allylic alcohol substrate is transformed into an optically active epoxyalcohol. In the case of chiral allylic alcohols, kinetic resolution results. Another example is Sharpless asymmetric dihydroxylation. In the example below the achiral alkene yields ...
The mechanism of copper-catalyzed allylic substitutions involves the coordination of copper to the olefin, oxidative addition and reductive elimination. Enantioselective versions of these reactions have been used in the synthesis of complex molecules, such as (R)-(-)-sporochnol and (S)-(-)-zearalenone.