Scheme 1: Reagents and conditions: (a) Ph3CCl, AgNO3, pyridine, r.t.; (b) BnBr, NaH, THF, r.t.; (c) TFA, n-BuOH, CH2Cl2, r.t.; (d) TsCl, pyridine, r.t.; (e) NaN3, DMSO, 100–150°C; (f) P(OBn)3, toluene, r.t. to 90°C; (g) Pd/C, H2, EtOAc/EtOH/H2O, r.t.; (h) MsCl, PS-PPh3, toluene, r.t. to 60°C; and (i) Pd/C, H2, EtOAc/EtOH/H2O r.t.