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软珊瑚群柱虫中的一个化学组分Ia,经乙酰化分离得到其衍生物Ib,用x射线晶体结构分析法测定Ib的晶体结构。Ib属正交晶系,空间群P2_12_12_1,a=12.722(2),b=14.726(4),c=12.255(3),z=4。由Ib的晶体结构分析结果推断Ia的分子式为C_(20)H-(33)O_4Cl。它是一个具有五、十一员双环碳骨架的新型含氯二萜。十一员环上带有一个环氧基和一个环外双键,分子中含有两个叔羟基和一个伯羟基。利用C1、O和C对Cukα辐射的反常散射,测定对于对映体敏感的Friedel反射对的Bijvoet差,确定了Ib的绝对构型,进而确定Ia的绝对构型。
One of the chemical constituents Ia in the soft coral group is isolated by acetylation and its derivative Ib is obtained. The crystal structure of Ib is determined by X-ray crystallography. Ib is an orthorhombic system, space group P2_12_12_1, a = 12.722 (2), b = 14.726 (4), c = 12.255 (3), z = 4. According to the crystal structure analysis results of Ib, the formula of Ia is C_ (20) H- (33) O_4Cl. It is a new type of chlorine-containing diterpene with a five-member bicyclic carbon skeleton. Eleventh ring with an epoxy group and an exocyclic double bond, the molecule contains two tertiary hydroxyl and a primary hydroxyl. Using the anomalous scattering of Cukα radiation by C1, O and C, the Bijvoet difference for the enantiomerically sensitive Friedel reflection pair was determined. The absolute configuration of Ib was determined and the absolute configuration of Ia was determined.