Hofer Margit, Greger Harald, Mereiter Kurt
Acta Crystallogr Sect E Struct Rep Online. 2009 Jul 22;65(Pt 8):o1942-3. doi: 10.1107/S1600536809027998.
THE TITLE COMPOUND [SYSTEMATIC NAME: (1S,3aS,4aR,4bS,5S,6R,6aR,10aR,10bR,12aS)-5,6-bis-(acet-yloxy)-1-(3-fur-yl)-1,5,6,6a,7,10a,10b,11,12,12a-deca-hydro-4b,7,7,10a,12a-penta-methyl-oxireno[c]phenanthro[1,2-d]pyran-3,8(3aH,4bH)-dione], C(30)H(36)O(9), is a limonoid-type triterpene isolated from Aglaia elaeagnoidea (A. Juss.) Benth. (Meliaceae) from Queensland, northern Australia. It contains the gedunin core of four trans-fused six-membered rings with an oxirane ring annelated to the fourth ring. A terminal 3-furyl unity and two acet-oxy groups in a mutual cis-disposition supplement the mol-ecule. A comparison between the gedunin cores of the title compound, the parent compound gedunin, and three further gedunin derivatives revealed considerable variations in their conformation stemming from the conformational lability of the first screw-boat ring and the third twist-boat ring. A sensitive measure for the third ring is one C-C-C-C torsion angle, which is 14.2 (2)° in the title compound, but varies in other cases from ca 20 to ca -40°. In the crystalline state, 6α-acetoxy-gedunin shows ten comparatively weak C-H⋯O inter-actions, with H⋯O distances in the range of 2.33-2.69 Å.
标题化合物[系统名称：(1S,3aS,4aR,4bS,5S,6R,6aR,10aR,10bR,12aS)-5,6-双-(乙酰氧基)-1-(3-呋喃基)-1,5,6,6a,7,10a,10b,11,12,12a-十氢-4b,7,7,10a,12a-五甲基-环氧乙烷[c]菲并[1,2-d]吡喃-3,8(3aH,4bH)-二酮]，C(30)H(36)O(9)，是一种柠檬苦素类三萜，从澳大利亚北部昆士兰州的米仔兰属植物（楝科）中分离得到。它含有四个反式稠合六元环的格杜宁核心，其中一个环氧乙烷环与第四个环稠合。一个末端3-呋喃基单元和两个相互顺式排列的乙酰氧基补充了该分子。标题化合物、母体化合物格杜宁以及另外三种格杜宁衍生物的格杜宁核心之间的比较表明，由于第一个船式环和第三个扭船式环的构象不稳定性，它们的构象存在相当大的差异。第三个环的一个敏感度量是一个C-C-C-C扭转角，在标题化合物中为14.2 (2)°，但在其他情况下从约20°到约-40°不等。在晶体状态下，6α-乙酰氧基格杜宁显示出十个相对较弱的C-H⋯O相互作用，H⋯O距离在2.33 - 2.69 Å范围内。
