Syntheses of 5-amino-3-(β-d-ribofuranosyl)imidazo [4,5-b] pyridin-7-one (1-deazaguanosine) and related nucleosides

The synthesis of 5-amino-3-(β-D-ribofuranosyl)imidazo4,5-b ]pyridin-7-one (1-deazaguano-sine) has been accomplished by three different methods. The 6-thioguanosine analog 5-amino-3-(β-D-ribofuranosyl)imidazo 4,5-b ]pyridin-7-thione (1-deaza-6-thioguanosine) has been prepared in situ by a reduction of the corresponding disulfide. The synthesis of various nucleoside precursors of the above compounds by several condensation procedures are described. The procedures used to unequivocally determine the site of ribosylation and anomeric configuration are also discussed.