Scheme 1. Synthesis of 12–17. Reagents and conditions: (a) NIS, AgOTf, –40 °C, 30 min; (b) 5% TFA, CH2Cl2, 0 °C, 20 min, 76% over two steps from 26; (c) NIS, AgOTf, CH2Cl2, –40 °C, 30 min, 61%; (d) NaOCH3, CH3OH, CH2Cl2, 3 h; (e) (Ph3P)4Pd, HOAc, overnight; (f) Pd–C, H2, CH3OH, CH2Cl2, overnight, 68% over three steps from 29; (g) NaOCH3, CH3OH/CH2Cl2, 3 h; (h) Pd–C, H2, CH3OH, CH2Cl2, overnight, 87% over two steps from 29; (i) NaOCH3, CH3OH, CH2Cl2, 5 h; (j) CH3I, NaH, DMF, 1 h, 81% over two steps from 29; (k) (Ph3P)4Pd, HOAc, overnight; (l) Pd–C, H2, CH3OH, CH2Cl2, overnight, 79% over two steps from 30; (m) Pd–C, H2, CH3OH, CH2Cl2, overnight, 78%; (n) (Ph3P)4Pd, HOAc, overnight; (o) CH3I, NaH, DMF, 1 h; (p) Pd–C, H2, CH3OH, CH2Cl2, overnight, 71% over three steps from 30; (q) (Ph3P)4Pd, HOAc, overnight; (r) Ac2O, pyridine, 2 h; (s) Pd–C, H2, CH3OH, CH2Cl2, overnight, 73% over three steps from 30.
