The reaction of an N-protected 3-bromo-4-(indol-3-yl)maleimide with methyl (2-nitrophenyl)acetates in the presence of base affords condensed cycloheptatriene derivatives which can be transformed into arcyriacyanin-type alkaloids. The unusual reaction sequence implies a heptatrienyl–cycloheptadienyl anion rearrangement followed by a 1,5-sigmatropic shift to yield the thermodynamically more stable cycloheptatriene derivative.
在碱存在下,N-保护的 3-溴-4-(吲哚-3-基)马来酰亚胺与(2-硝基苯基)乙酸甲酯反应生成缩合环庚三烯衍生物,这些衍生物可转化为arcyriacyanin类生物碱。不寻常的反应顺序意味着庚三烯-环庚二烯阴离子重排,然后发生 1,5-sigmatropic 转变,生成热力学上更稳定的环庚三烯衍生物。