FIG 1.

Synthesis of CPV-TP enantiomers (+)-4 and (−)-4. The reaction conditions were as follows: (A) (a) (1) Me₃SiCl, imidazole, pyridine; (2) I₂; (b) (1) Bu₃N, N,N′-carbonyldiimidazole; (2) MeOH. (3) (Bu₃NH)₄P₂O₇, MeOH; (4) NH₄OH, 48 h, room temperature; (B) (a) Ac₂O, AcONEt₄, pyridine; (b) (1) Bu₃N, N,N′-carbonyldiimidazole; (2) MeOH; (3) (Bu₃NH)₄P₂O₇, MeOH; (4) NH₄OH, 3 h. According to the tentative configurational assignment of the corresponding CPV monophosphates (7), the CPV triphosphate (+)-4 can be assigned the S configuration and (−)-4 can be assigned the R configuration.