2-甲基-1,3-环己二酮的合成

Synthesis of 2-methYl-1, 3-cyclohexadione

2-甲基-1,3环-己二酮是合成甾体和萜类等多环化合物的起始原料,笔者以丙酮、甲醛和盐酸二乙胺为原料制备成曼尼赫碱Ⅰ,它的甲基碘化物与丙二酸二乙酯缩合得化合物Ⅱ,经脱羧得化合物Ⅲ,Ⅲ合环后再甲基化得到预期产物2-甲基-1,3-环己二酮(Ⅳ)。这条合成路线具有原料易得,反应条件温和,合成步骤较少等特点。合成路线用反应式表示如下:

The reaction of Mannich base I and methyl iodide produces 4-diethyl-aminobutan-2-one methiodide. The condensation between the methiodide and diethyl malanate by base-catalyzed give compound Ⅱ, Ethyl 5-oxo hexanoate (Ⅲ) is obtained by decarboxylation of Ⅱ in DMSO, which is treated with Sodium ethoxide and methyl iodide, then the 2-methyl-1, 3-eyclohexadione (Ⅳ) is obtained.