Racemic compounds Sharpless epoxidation

Kinetic resolution is the achievement of partial or complete resolution by viitue of unequal rates of reaction of the enantiomers in a racemate with a chiral catalyst [5]. The method usually forms two products one enantiomer does not react with the chiral catalyst or else it reacts very slowly whilst the other enantiomer reacts with the aid of the chiral catalyst to form a new product which may or may not be chiral. As a result two different compounds now make up the mixture and can be separated by conventional chromatographic techniques. One of the most widely applied examples of this technique is the Sharpless Kinetic Resolution. This asymmetric epoxidation of ally lie alcohols was reported by Sharpless in 1980 catalysed by a titanium (IV) tartrate complex in the presence of a hydroperoxide [6] and has been employed in a number of kinetic resolutions [7]. This reaction shows remarkable... 

Oxiranecarboxylic acids 41 (glycidic acids) can be converted into a,P epoxy diazomethyl ketones 42 via mixed anhydrides. It was found that photolysis of these compounds in the presence of alcohols gave yhyunsaturated esters 44. It is thought that nucleophilic attack of the alcohol on the ketene 43 results in epoxide ring opening. The E olefin isomer is predominately formed, although small quantities of Z esters are also isolated (< 10%). Conveniently non-racemic, chiral substrates are readily prepared via Sharpless asymmetric epoxidation of allylic alcohol 39, followed by... 

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