Scheme 9.
Synthesis of compounds 25a and 25b. Reagents and conditions: (a) (diacetoxyiodo)benzene, KOH, MeOH, rt; (b) 1, NH4OAc, O2, EtOH, 65 °C, 16 % for 25a, 43 % for 25b.
Synthesis of compounds 25a and 25b. Reagents and conditions: (a) (diacetoxyiodo)benzene, KOH, MeOH, rt; (b) 1, NH4OAc, O2, EtOH, 65 °C, 16 % for 25a, 43 % for 25b.