Scheme 6.

Synthesis of (4'(R)-C-phenyl-D-ribo-tetrofuranosyl)adenine analogue 69.

Reagents and Conditions: (i) (a) Cyclohexanone, FeCl₃, Sikkon, 50 °C, 2.5 h, 89%; (b) NaOH, H₂O, NaIO₄, 0 °C then BaCl₂.10 H₂O, 4 °C, 10 min, 93%; (ii) CH₃OCH₂OPhLi, Et₂O, 10 °C, 3 h, 65: 30%, 66: 35%; (iii) DIBAL-H, toluene −78 °C, 10 min, 95%; (iv) (a) aq. HCl (0.2 M), 50 °C, 7 h; (b) Ac₂O, pyridine, 90% for the two steps; (v) (a) N⁶-benzoyladenine, HDMS, TMSOTf, CH₃CN, 60 °C, 1 h; (b) NH₃, MeOH, rt, 48 h, 68% for the two steps.