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目的:对甘草次酸(Ⅰ)经还原修饰得到11-羟基甘草萜醇类衍生物,并考察制备工艺条件。方法:以化合物(Ⅰ)为原料,利用Red-Al和四氢铝锂等两种还原剂对C11-羰基和C30-羧基进行选择性还原,并利用简单的单因素分析法考察反应温度和时间对反应产率和分离纯化效果的影响。结果:通过还原反应获得11-羟基甘草萜醇类两种光学异构体18β-Olean-12-ene-3β,11α,30-triol(Ⅱ)和18β-Olean-12-ene-3β,11β,30-triol(Ⅲ),并进行光谱鉴定。2种还原方法结果表明,利用Red-Al还原化合物(Ⅰ)时,最佳反应条件为60℃/1 h,产率87%;利用四氢铝锂还原(Ⅰ)时,最佳反应条件为60℃/2 h,产率52%。结论:还原剂Red-Al和四氢铝锂在甘草次酸C11-羰基和C30-羧基的选择性还原中具有重要意义,其中利用Red-Al对甘草次酸进行还原修饰要比用四氢锂铝容易、产率高。
Objective: The glycyrrhetinic acid (Ⅰ) was modified to obtain 11-hydroxy licoricetiol derivatives, and investigated the preparation conditions. Methods: Compound (Ⅰ) was used as raw material to selectively reduce C11-carbonyl and C30-carboxyl with two reducing agents such as Red-Al and lithium aluminum hydride. The reaction temperature and time were investigated by simple one-factor analysis On the reaction yield and the effect of separation and purification. Results: Two optical isomers of 18-Olean-12-ene-3β, 11α, 30-triol (Ⅱ) and 18β-Olean-12-ene-3β, 11β, 30-triol (Ⅲ) and identified by spectroscopy. The results of the two reduction methods showed that the optimum reaction conditions for the reduction of compound (Ⅰ) with Red-Al were 60 ℃ / 1 h and the yield was 87%. The best reaction conditions were as follows: 60 ℃ / 2 h, yield 52%. CONCLUSION: Reducing agent Red-Al and lithium aluminum hydride are important in the selective reduction of C11-carbonyl and C30-carboxyl of glycyrrhetinic acid. Among them, the reductive modification of glycyrrhetinic acid by Red-Al is better than that of lithium- Aluminum easy, high yield.