h, 72% for 5; 3 h, 28% for 6; 5.5 h, 60% for 7; 5.5 h for 8. (ii) 2 M aqueous solution LiOH, 0 °C, 0.5 h, 36% for 8.
Scheme 3 Synthesis of dinucleosides 10–13. (a) Ns-Cl, NEt3, DMF, 25 °C, 3.5 h, 40–72%; (b