【摘要】 <正> 前报报道了土槿甲酸（1）和土槿乙酸（2）的化学结构。土槿皮中的另一成分土槿丙酸（3）已证明为去乙酰基土槿乙酸。我们将柱层析分去1,2后的洗脱流分,重复进行硅胶柱层析,除获得3外,还得到一个R_f值与3相近但具有双熔点的成分,定名土槿丙₂酸,经鉴定为去甲基土槿乙酸（4）。前报1和2的碳架系通过土槿甲酸结晶的X射线衍射分析确定。本文通过沟通1～4的结构关系,即由1经数步氧化反应,分别证明产物为2,3和去乙酰基去甲基土槿乙酸更多还原

【Abstract】 Pseudolaric acid C （3） and pseudolaric acid C₂（4） have been isolated from the crude pseudolaric acid together with pseudolaric acid A （1） and pseudolaric acid B （2）. Pseudolaric acid C₂ was proved to be demethylpseudolaric acid B. Oxidation of pseudolaric acid A with selenium dioxide gives two products, A and B. The former is a primary alcohol and the latter, an aldehyde. Their structures were proved to be 6 and 7 respectively by 1^H NMR. Further oxidation of 7 with active manganese dioxide in methanol in the presence of sodium cyanide yields pseudolaric acid B and a byproduct, deacetylpseudolaric acid B which is identical with pseudolaric acid C. Alternatively further oxidation of the aldehyde 7 with silver nitrate in alkaline solution affords deacetyl-demethylpseudolaric acid B（5）. Hydrolysis of pseudolaric acid B in aqueous potassium hydroxide yields demethylpseudolaric acid B or pseudolaric acid C₂.Hydrolysis of pseudolaric acid B in methanolic potassium hydroxide solution yields deacetylpseudolaric acid B or pseudolaric acid C. The structures of the four new diterpenic acids are correlated to each other. It confirms that all of them possess the same carbon skeleton.更多还原