基于F-C反应的天然产物大豆黄素合成工艺

引言 大豆黄素(又名大豆苷元、大豆黄酮,daid-zein),化学名为4',7-二羟基异黄酮,是从大豆中提取得到的一种异黄酮活性组分,是大豆异黄酮的一种,属大豆苷类中的游离型的苷元,因豆科植物中的大豆异黄酮大多以糖苷形式存在,故以游离型苷元形式存在的大豆黄素在豆科植物中的含量非常低,大约为0.1%,提取、分离过程都很困难,存在生产成本高、投资较大、工艺复杂、产品纯度低等问题.大豆黄素及其糖苷的结构如下

Process for synthesis of daidzein based on Friedel-Crafts reaction

Daidzein was synthesized from 1,3-dimethoxybenzene and p-methoxyphenylacetic acid using a process containing chlorination, Friedel-Crafts acylation, demethylation, cyclization and demethylation. Because of methyl protection, reactivity of hydroxy groups was reduced and the yield of Friedel-Crafts reaction reached to 93.6%.Hydrobromic acid(40%)was used as demethylation reagent, and all methyl in 4′,7-dimethoxyisoflavone molecule could be removed.The effect of process parameters such as catalyst amount, reaction temperature and molar ratio of materials were studied, and their optimal values were as follows:(1)in Friedel-Crafts reaction, the ratio of catalyst(aluminum chloride)and 1,3-dimethoxybenzene 1.1∶1, reaction temperature 25℃,(2)in demethylation, the ratio of demethylation reagent(aluminum chloride)and 2,4,4′-trimethoxydeoxybenzoin 1.1∶1,(3)in cyclization reaction, the ratio of triethyl orthoformate and 2-hydroxy-4,4′-dimethoxydeoxybenzoin 2∶1, reaction temperature 135℃,(4)in demethylation reaction of 4′,7-dimethoxyisoflavone, reaction temperature 122℃.The structure of product was characterized by ¹H NMR and MS.