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Nukleozydy 8-azapurynowe : synteza i aktywność biologiczna

Głowacka I. E., Zdzienicka A.

Wiadomości Chemiczne

2017

[Z] 71, 3-4

147--174

The synthetic approaches to 8-azapurine nucleosides and their biological activities have been reviewed. This class of compounds could serve as antimetabolites of purine nucleoside with potential clinical applications [1–6]. They were primarily synthesized by glycosylation of 8-azapurines, which could be easily prepared from appropriately substituted 4,5-diaminopyrimidines when reacted with nitric(III) acid [1]. Since in 8-azapurines at least three nitrogen atoms could serve as nucleophilic centers the regiochemistry of glycosylation was discussed in details. Generally, mixtures of N9, N8 and N7-substituted 8-azapurine nucleosides were formed when reactions were carried out at room temperature (kinetic control), while N9-substituted analogs were produced at elevated temperatures (thermodynamic control). On the other hand, no differences in the stereochemical outcome of glycosylation were noticed for canonical purine nucleobases and their 8-aza analogues since ratios of α and β anomers appeared to be closely related to the structure of a sugar component. Multidirectional biological activities of 8-azapurines and their nucleosides, including antitumor, antiviral and antibacterial, were presented for the most acclaimed examples. However, none of these compounds was approved as a drug. The current interest in 8-azapurines and their nucleosides takes advantage of a significant fluorescence (opposite to purines), which was found to be a pH-dependent thus providing an excellent tool for advanced studies in nucleic acid chemistry.