Scheme 1.

Reaction conditions: (A) CDI, Et₃N, THF, 60 °C, 24 h, 27–85%; (B) NaH; ethyl chloroacetate, THF, rt, 24 h, 19–82%; (C) (i) Boc₂O, Et₃N, DCM, 0 °C, rt, 24 h, 83-99%; (ii) SOCl₂, imidazole, Et₃N, DCM, −40 °C, 2 h; then at rt for 2 h, 55–94%; (iii) RuCl₃, NaIO₄, MeCN:H₂O (1:1), 0 °C to rt, 3 h, 31–95%; (iv) TFA, DCM, rt, 24 h, 66–90%; (D) (i) ClCH₂SO₂Cl, Et₃N, DCM, 0 °C to rt, 6 h, 34-84%; (ii) PMB-Br, K₂CO₃, DMF, rt, 1 h, 17–89%; (iii) Cs₂CO₃, DMF, 80 °C, 24 h, 55–78%; (iv) CAN, MeCN:H₂O (9:1), rt, 24 h, 24–78%; (E) (i) Boc₂O, Et₃N, DCM, 0 °C, rt, 24 h, 83–99%; (ii) t-butyl acrylate, Cs₂CO₃, t-BuOH, 24 h, 75–99%; (iii) 4.0 M HCl in dioxane, 24 h, 97–99%; (iv) T3P, Et₃N, dioxane, 24 h, rt, 33–86%; (F) (i) TBS-Cl, Et₃N, DCM, 0 °C to rt, 24 h, 71–95%; (ii) chloroethane sulfonyl chloride, Et₃N, 0 °C to rt, 2 h, 75–95%; (iii) MeI, K₂CO₃, MeCN, 72 h, 70–90%; (iv) TBAF, THF, 2 h, 38–91%.