© 2008 Oxford University Press
This article appears in the following Nucleic Acid Symposium Series issue: Joint Symposium of the 18th International Roundtable on Nucleosides, Nucleotides and Nucleic Acids and the 35th International Symposium on Nucleic Acids Chemistry [View the issue table of contents]
Regioselective glycosylation of 7-azapteridines and conversion of the 7-azapteridine nucleosides into 6-azapurine nucleosides
Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1, Tsushima-naka, Okayama 700-8530, Japan
*Corresponding author. E-mail: nagamatsu{at}pheasant.pharm.okayama-u.ac.jp
Abstract
The regioselective glycosylation of reumycins (3) reacted with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (4) and BSTFA in acetonitrile at 90 °C followed by reaction of SnCl4 in dioxane at room temperature afforded the 1-(2',3',5'-tri-O-benzoyl-β-Dribofuranosyl)- 6-methylpyrimido[5,4-e][1,2,4]triazine-5,7(1H,6H)-diones (5) (toxoflavin type nucleosides), while the similar alkylations with 1-bromo-2,3,5-tri-Obenzoyl- β-D-ribofuranose (6) and KHCO3 in DMF at 100 °C gave predominantly the 8-(2',3',5'-tri-Obenzoyl- β-D-ribofuranosyl)-6-methylpyrimido[5,4-e]- [1,2,4]triazine-5,7(6H,8H)-diones (7) (fervenulin type nucleosides). On the other hand, treatment of the 7- azapteridine nucleosides (5 and 7) in alkali solution at room temperature yielded the corresponding 1-(β-Dribofuranosyl)- 5-methyl-1H-imidazo[4,5-e][1,2,4]- triazin-6(5H)-ones (8) and 7-(β-D-ribofuranosyl)-5- methyl-5H-imidazo[4,5-e][1,2,4]triazin-6(7H)-ones (9) [6-azapurine nucleosides] by benzilic acid rearrangement. Some 7-azapteridine nucleosides (5 and 7–9) showed antitumor activities and anti-coccidiosis activities.