新型3-甲基吲哚衍生物的合成

Synthesis of novel 3-methylindole derivatives

2-甲酰基(乙酰基)-3-甲基吲哚衍生物是合成吲哚取代俘精酸酐类光致变色染料的重要中间体。以3-甲基吲哚为原料,先在NaH存在下,以碘甲烷和2-溴乙基甲基醚为亲电试剂发生N-烷基化反应,再通过Vilsmeier-Haack反应在3-甲基吲哚的2位引入甲酰基,制备出两种N-取代基-2-甲酰基-3-甲基吲哚衍生物,产率分别为55%和35%;选择ZnCl2作催化剂,3-甲基吲哚与乙酰氯发生Friedal-Crafts反应选择性生成2-乙酰基-3-甲基吲哚,再发生N-烷基化反应,合成一系列N-取代基-2-乙酰基-3-甲基吲哚衍生物,产率为34%～89%。其中4种新化合物的结构经1HNMR、13CNMR、元素分析和MS光谱表征确定。

2-Formyl（acetyl）-3-methylindole derivatives are important intermediates for the synthesis of fulgide photochromic dyes.3-Methylindoles were first N-alkylated to form 1-methyl or methoxyethyl compounds,then one formyl was introduced via Vilsmeier-Haack reaction.Two intermediates were prepared by this strategy.The total yields are 55% and 35% respectively.The trial to acetylated of 2-position of indoles did not afford desired products.ZnCl2 was used as Lewis acid,3-methylindoles could react with acetyl chloride in 2-position of indoles to form 2-acetyl-3-formyl indoles.The reactions are mild without protection and deprotection.A series of 2-acetyl-3-methyl indloes were prepared,their yields are 34%~89%.Four of these compounds were not reported in the literature.The structures were confirmed by 1HNMR,13CNMR,MS and element analysis.