Fig. 4.

Application of the two-phase C–H oxidation/ring expansion strategy to picfeltarraegenin and kirenol. a Electrochemical allylic C–H oxidation/ring expansion of picfeltarraegenin. b Allylic C–H oxidation/ring expansion of kirenol. (i) MOMCl, DIPEA, DMAP, CH₂Cl₂, rt; (ii) (a) NaBH₄, EtOH, rt, (b) MOMCl, DIPEA, DMAP, CH₂Cl₂, 50 °C; (iii) LiClO₄, Py, t-BuOOH, Cl₄NHPI, acetone, rt. (iv) Pd/C, H₂, MeOH, rt; (v) NH₂OH•HCl, KOAc, (c) TsCl, DMAP, Py, 60 °C; (vi) (a) CDI, toluene, 90 °C, (b) MOMCl, DIPEA, DMAP, CH₂Cl₂, rt; (vii) (a) SeO₂, dioxane, (b) (COCl)₂, DMSO, Et₃N, CH₂Cl₂; (viii) (a) Pd/C, H₂, EtOAc, (b) NH₂OH•HCl, KOAc, 70 °C, (c) TsCl, DMAP, Py, 60 °C. Full details are in Supplementary Figure 12