Regioselectivity and mechanism of transpurination reactions in the guanine nucleosides series

Abstract

The transpurination reaction of the fully acetylated derivatives of guanosine and its 7-β-D-ribofuranosyl regioisomer with 2-acetoxyethyl acetoxymethyl ether has been studied using high performance liquid chromatography (HPLC). The regioselectivity of glycosyl exchange observed in the early stages of the reaction suggests that the unsubstituted nitrogen atoms of the imidazole portion (N7 and N9) are, exclusively, sites of direct glycosylation in the case of guanine derivatives. The results lead to the conclusion that the mechanism of the glycosylation reaction of guanine is different to that of adenine.

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