Conversion to epoxides

Alkene conversion to epoxide (%) Epoxide selectivity (%) Epoxide conversion (%) Cyclic carbonate selectivity (%)... 

When the oxidation was carried out at ambient temperature, negligible conversion to epoxide was observed this is believed to be due to the instability of Oxone in the basic medium at this temperature [23]. 

Overall, the differences in enantiomeric excess between the two solvent systems were generally not as vast as those observed in reactions with 1-phenylcyclohexene. However, the conversions to epoxide differed significantly all the experiments recorded in dichloromethane required longer reaction times, and in some cases still did not reach the level of conversion observed using the dichloromethane/ acetonitrile system. 

The highest ee (50%) was obtained when the reaction was carried out at —78 °C (entry 18). Under these conditions (using 10 mol% of catalyst), the conversion to epoxide is rather low (15%). Surprisingly, the p-methoxyaryl catalyst (37) is not as selective as it is under the aqueous conditions, the best ee being only 29% (45% ee in the original aqueous conditions). 

A number of variations on the procedure exist and have been reviewed by Privett [737]. For example, the positions of double bonds in monoenes containing both cis- and fr"ans-isomers, can be determined by conversion to epoxides, of which the configurational isomers are readily separable, and cleavage of these with periodic acid [245]. Similarly, partial oxymercuration of the double bonds followed by mass spectrometric identification of the products has been applied to the analysis of polyunsaturated fatty acids [719],... 

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