Treatment of 4-azido-2-pyrimidinone nucleoside 1 with MeOH/K2CO3 or ammonium hydroxide led to derivatives 2 and 3, respectively. Both compounds derived from a nucleophilic addition at the modified base 2-position. These results contrast with the previously reported sensitivity of the 4-azido-2-pyrimidinone nucleoside 6-position to nucleophiles.