Transglycosylation to l-3-azido purines starting from LdT. Reagents and conditions: (a) 1 eq LdT, 1.02 eq TBSCl, pyridine, CH2Cl2, rt, 18 h, 92%; (b) DIAD, tpp, tol, 80 °C, 30 min, 79%; (c) LiN3, dmf, 130 °C, 2 days, 67%; (d) BSA, TMSOTf, acetonitrile, 85 °c, 18 h, 81%; (e) TBAF, rt, 16 h, 35%; (f) t-BuMgCl, phenyl ethoxyalaninyl phosphorochloridate, THF, rt, 18 h, 27%.