5,7-二甲氧基香豆素合成方法的改进

An improved synthesis method of 5,7-dimethoxycoumarin

以间苯三酚为原料,选甲醇进行甲基化反应制备3,5-二甲氧基苯酚,以丙炔酸乙酯经Pechmann环化反应制备了白柠檬素(5,7-二甲氧基香豆素)。考察了甲基化反应、环化反应的影响因素,结果表明n(间苯三酚)∶n(甲醇)=1∶15,干燥氯化氢为催化剂,75℃反应7h,甲基化收率为82%;n(丙炔酸乙酯)∶n(3,5-二甲氧基苯酚)∶n(无水氯化锌)=1∶3∶1,环化温度为100℃,N2保护下反应2h,环化反应收率为88%,两步反应总收率达73%。目标产物用红外、质谱、核磁分析手段进行了表征和分析。

3,5-Dimethoxyphenol was synthesized through methylation reaction by phloroglucinol and methanol, which reacted with ethyl propiolate by Pechmann reaction to get limettin （5,7-dimethoxycoumarin）. Some factors of methylation and cyclization were studied,which showed that the yield of methylation was up to 88.6% when n（phloroglucinol） ：n（ methanol） = 1：15 ,reacting for 7h under 75℃ with the catalysis of dry H C1 ;and when n （ethyl propiolate） ：n（3,5-dimethoxyphenol） ：n（ZnC12） = 1：3：1, reacting for 2h under 100℃ ,with N2 protection,the yield was 84. 6%. Finally the product was 75% in total yield. The structure of the target compounds were characterized by IR, GC-MS,and 1H NMR.