Scheme 3.

Syntheses of Analogues 33–35^a

^aReagents and conditions: (a) Dess–Martin periodinane, DCM, RT, and 2 h; (b) NaN₃, CF₃SO₃H, ACN, RT, and 12 h; (c) (CH₃)₃Sn–OH, dichloroethane, MW, 110 °C, and 1 h; (d) Deoxo-Fluor, DCM, RT, and 12 h; (e) P(t-Bu)_3.HBF₄, ([PdCl(allyl)]₂, dioxane, 80 °C, and 4 h; and (f) LiOH, THF/MeOH/H₂O, and 1 h.