Ketonucleosides stability

The use of ketonucleosides as synthetic intermediates is based on their stability, particularly in alkaline media. Unlike ketopentosylpyrimi-dines, which are rapidly decomposed, ketohexose nucleosides appear to be convenient intermediates for syntheses of branched-chain, deoxy, and rare sugar nucleosides. 

Other pyrimidine keto-nucleosides, such as 47a and 47b, could be treated with acetic anhydride-pyridine without glycosylic cleavage.33 The stability of 47a and 47b in this medium permitted elaboration of a new, mild, regioselective synthesis of enol acetates, The reaction of 4 -ketonucleosides of uracil with acetals of N,N-dimethylformamide led,33 after addition of acetic anhydride, to the corresponding enol acetate-nucleosides 77a and 77b. 

Study of the stability of these ketonucleoside derivatives in alkaline media has shown that they can readily revert to the starting ketone. 

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See also in sourсe #XX -- [ , , ]

See also in sourсe #XX -- [ , , , ]

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