Bromination of N-acetyl-2,3-dimethylindole 11 in the presence of excess methanol at room temperature gave a mixture of products consisting of cis and transN-acetyl-2,3-dimethoxy-2,3-dimethylindoline 17 and 18,3-methoxy-2,3-dimethylindolenine 19, and N-acetyl-3-methoxymethyl-2-methylindole 21. The same reaction performed at −40 °C yielded a mixture of 17, 18, and N-acetyl-2-methoxy-2-methyl-3-methyleneindoline 22. Bromination of 11 at low temperature in the presence of 1.5 equivalents of methanol followed by treatment with triethylamine yielded 22 quantitatively. Treatment of 22 with acidic methanol readily gave 21. The mechanistic implications of these transformations are considered.
在室温下过量甲醇存在的情况下对N-乙酰-2,3-二甲基吲哚11进行溴化反应,得到了一种产物混合物,包括顺式和反式N-乙酰-2,3-二甲氧基-2,3-二甲基吲哚啉17和18、3-甲氧基-2,3-二甲基吲哚烯19,以及N-乙酰-3-甲氧基甲基-2-甲基吲哚21。在−40°C下进行相同的反应得到了17、18和N-乙酰-2-甲氧基-2-甲基-3-亚甲基吲哚啉22的混合物。在低温下,在存在1.5当量甲醇的情况下对11进行溴化反应,然后用三乙胺处理可以定量得到22。用酸性甲醇处理22可以轻松得到21。考虑了这些转化的机理意义。