Scheme 9

Synthesis of the phosphoramidate nucleolipids. a) dAMP, DCC, t- BuOH, H₂O, reflux, 2 h; b) TMP, DCC, t- BuOH, H₂O, reflux, 2 h; c) 0.5 N NaOH, MeOH, rt. Compounds 52 and 54 were isolated as 2Na ⁺ salt.