7-Deazainosine derivatives: synthesis and characterization of 7-and 7,8-substituted pyrrolo[2,3-d]pyrimidine nucleosides

The synthesis of model 7 deazapurine derivatives related to tubercidin and toyocamycin has been performed. Tubercidin derivatives were obtained by simple conversion of the amino group of the heterocyclic moiety of the starting 7-deazadenosine compounds, into hydroxyl group. Preparation of toyocamycin derivatives was accomplished by treatment of the silylated 6-bromo-5-cyanopyrrolo[2,3-d]pyrimidin-4-one with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose. The glycosylation reaction afforded a mixture of 7-ciano, 8-bromo, 2’,3’,5’ tri-O-benzoyl, 7-deazainosine and 6-bromo-5-cyano-3-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)pyrrolo[2,3-d]-pyrimidin-4-one isomers: the structures were assigned on the basis of NMR spectroscopy studies. Next deprotection treatment gave the novel 7-deazainosine ribonucleosides.