Convergent Total Syntheses of the Amaryllidaceae Alkaloids Lycoranine A, Lycoranine B, and 2‑Methoxypratosine

The title alkaloids, 1, 2, and 3 respectively, have been
prepared in a convergent manner
by two related routes. The superior one involves C–H functionalization
of the relevant 5-methoxyindole at C-7 using Hartwig’s protocol
and thus forming the corresponding borolated indole that could be
coupled with the requisite 2-bromobenzoate to deliver the title natural
products. Single crystal X-ray analyses of the synthetically derived
samples of compounds 1 and 2 are reported.

本文所指的生物碱1、2和3，通过两条相关路线以汇聚式合成策略完成制备。其中最优路线采用哈特维希（Hartwig）方法，在C7位对目标5-甲氧基吲哚进行C-H官能化反应，得到相应的硼化吲哚中间体，随后将该中间体与所需的2-溴苯甲酸酯进行偶联反应，最终得到标题所述的天然产物。本文还报道了化合物1和2的合成样品的单晶X射线衍射分析结果。