The reactivity of N1-alkylsulfonyl-and N1-arylsulfonyl-2′, 3′, 5′-tri-O-acetylinosine with benzylamine and with 15NH3, regarding the attack on C2, has been shown to be in the order CF3SO2 (Tf)> 2, 4-(NO2) 2C6H3SO2 (DNs)⩾ 4-NO2C6H4SO2 (pNs)≈ C6F5SO2 (PFBs)> 2-NO2C6H4SO2 (Ns)≫ CH3SO2 (Ms)> 4-CH3C6H4SO2 (Ts)> 2, 4, 6-(CH3) 3C6H2SO2 (Mts). In spite of its intermediate reactivity, the Ns group is the most ...