Fructose with 0-ketonic esters

The reaction of ethyl acetoacetate with simple hydroxy ketones has been compared with the corresponding reactions of the ketoses. The results obtained with l-hydroxy-2-propanone and 3-hydroxy-2-butanone, under the same experimental conditions as with D-fructose, establish a parallel between these reactions. However, as in the case of the aldoses, the yield is greater for these simpler hydroxy ketones than for the ketoses.9 The resultant esters, (XV and XVI), were obtained in the form of sirups, but the free acids, (XVII and XVIII), and their phenacyl esters are crystalline. The acids were shown to be identical with those of known structure described in the literature.9... 

Owing to the low reactivity of the in situ formed dioxiranes, they suffer decomposition processes to give the corresponding Bayer-VilUger oxidation products. Therefore, new ketones with enhanced stability have been introduced to perform the aforementioned epoxidation. One of these ketones was the fructose derivative 62a [68], which efficiently catalyzed the oxidation of different cinnamate esters with higher yields (40-96%) and improved enantioselectivities (up to 97% ee). Surprisingly, the epoxidation of the related ethyl ( -cinnamate gave a lower result (84%, 44% ee). 

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