Mild and regioselective nitration of 1-deazapurine nucleosides using TBAN/TFAA

To obtain selectively functionalized 1-deazapurine nucleosides, the nitrating mixture tetrabutylammonium nitrate/trifluoroacetic anhydride (TBAN/TFAA) has been studied. This mixture demonstrated several merits: the use of an easy to handle reagent, mild reaction conditions and high selectivity for nitration in the pyridine ring. Nitration occurred at the α or β-position with respect to the pyridine nitrogen atom, depending on the substituents in the ring. Electron withdrawing substituents in the pyridine ring showed a positive effect on this nitration.