Epoxides and Oxaziridines

3-Epoxycyclohexanone of 20% ee was first prepared in 1980 by an enantioselecti-ve epoxidation of 2-cyclohexenone. However, enantiomerically pure 3-methyl- (34), 

5-dimethyl- (35) and 3,5,5-trimethyl-2,3-epoxycyclohexanone (36) can easily be prepared in 18, 30 and 35% yields, respectively, by inclusion complexahon of their racemic compounds with the chiral host 8 [16]. 

Preparation of enantiomerically active (3-ionone epoxide by a solid-state kinetic resolution in the presence of the chiral host Ic is also possible. When a mixture of Ic, 3-ionone (37) and m hloroperbenzoic acid (MCPBA) is ground by mortar and pestle in the solid state, +)-3 of 88% ee was obtained [17]. The mechanism of the kinetic resolution in the solid state is as follows. Firstly, oxidation of 37 with MCPBA gives rac-p-ionone epoxide (38). Secondly, enantioselective inclusion of (-i-)-38 with Ic occurs. Thirdly, uncomplexed (-)-38 is further oxidized to give the Baeyer-Villiger oxidation product (-)-39 of 72% ee. This is the first example of an enantiomeric separation by enantioselective complexahon in the solid state [17]. 

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