Scheme 4. Synthesis of Analogues 11a–da.
aReagents and conditions: (a) 1,2,3-benzotriazole, AlCl3, THF, overnight; (b) MnO2, acetone, 55 °C, 24 h, 35–71% in two steps.
aReagents and conditions: (a) 1,2,3-benzotriazole, AlCl3, THF, overnight; (b) MnO2, acetone, 55 °C, 24 h, 35–71% in two steps.