Doi Mitsunobu, Nakamori Terue, Shibano Makio, Taniguchi Masahiko, Wang Nian He, Baba Kimiye
Osaka University of Pharmaceutical Sciences, Nasahara, Takatsuki, Osaka 569-1094, Japan.
Acta Crystallogr C. 2004 Nov;60(Pt 11):o833-5. doi: 10.1107/S0108270104024291. Epub 2004 Oct 31.
Candibirin A [systematic name: 9,9'-(1,4-dioxane-2,5-diyldimethylenedioxy)di(7H-furo[3,2-g]chromen-7-one)], a new furanocoumarin dimer, was isolated from Heracleum candicans WALL. (1)H NMR and MS spectra had indicated that the title compound was a dimer of heraclenin or heraclenol, but the linkage structure and its chirality were undetermined. The dioxane linkage, having the R,R configuration, has now been elucidated from dimethyl sulfoxide-solvated crystals, C(32)H(28)O(10).2C(2)H(6)OS. Candibirin A is thus a dimerization product from heraclenin formed by reaction at the epoxy group. Dimethylformamide-solvated crystals, C(32)H(28)O(10).C(3)H(7)NO, adopt a different conformation, with a folded structure that differs from the extended structure in the dimethyl sulfoxide solvate. However, the puckering of the dioxane linker unit is very similar in the two conformers. This result shows that the rotation of the ether bonds, in the linker between the furanocoumarin and dioxane moieties, causes the conformational flexibility of (I).
坎迪比林A [系统名称：9,9'-(1,4-二氧六环-2,5-二亚甲基二氧基)二(7H-呋喃并[3,2-g]色原酮-7-酮)]，一种新的呋喃香豆素二聚体，是从白花独活（Heracleum candicans WALL.）中分离得到的。(1)H NMR和MS光谱表明标题化合物是异欧前胡素或异欧前胡醇的二聚体，但连接结构及其手性尚未确定。现已从二甲基亚砜溶剂化晶体C(32)H(28)O(10).2C(2)H(6)OS中阐明了具有R,R构型的二氧六环连接结构。因此，坎迪比林A是异欧前胡素在环氧基处反应形成的二聚产物。二甲基甲酰胺溶剂化晶体C(32)H(28)O(10).C(3)H(7)NO具有不同的构象，其折叠结构与二甲基亚砜溶剂化物中的伸展结构不同。然而，二氧六环连接单元的褶皱在两种构象中非常相似。这一结果表明，呋喃香豆素和二氧六环部分之间连接体中的醚键旋转导致了(I)的构象灵活性。
