Investigation of 8-Aza-7-Deaza Purine Nucleoside Derivatives

Glycosylation of 6-amino-4-methoxy-1H-pyrazolo[3,4-d]pyrimidine and its iodo- and bromo- analogues with the protected ribofuranose and 2′-deoxyribofuranose under different conditions resulted in the synthesis of N(9)- and N(8)-glycosylated purine nucleosides. Five key intermediate nucleosides, having 6-methoxy, 7-iodo, and 2-bromo groups, were further derivatized to 23 final 8-aza-7-deazapurine nucleoside derivatives. The structures of N(9)- and N(8)-glycosylated products were assigned based on UV and NMR spectra. HMBC analysis of 2D NMR spectra and X-ray crystallographic studies of the representative compounds unambiguously verified the connection of ribose ring to N(9)- or N(8)-position of the purine ring. The anticancer activity of these new compounds was evaluated.