Shaohui Chen
1984
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Journal
Acta Chimica Sinica
Abstract
Guan-fu base G (C_(26)H_(33)O_7N) is a new alkaloid isolated from the Chinese drug Guan-Bai-Fu-Tzu [Aconitum coreanum (Levl.) Raipaics]. Its methyliodide (C_(26)H_(33)O_7N·CH_3I) was prepared in the usual way and crystallized from acetone-ether as colourless and transparent orthorhombic crystals. The space group is D_2~1-P2_12_12_1.There are four molecules per unit cell. The lattice parameters are a=16.87A.b=16. 93A, c=10.09A.The three dimensional data were collected with MoK_a radiation on a Philips PW1100 four-circle diffractometer. There are 2848 independent reflections. First,coordinates of the iodine atom were derived from Patterson function. Subsequently three dimensional Fourier synthesis were calculated. After several cycles all 35 non-ydrogen atoms were found. During this process. the information which came from irect analysis of Patterson map was used as reference. Finally, the refinement of the structure was achieved using least-squares refinement. The R factor was 0.0578 when all 36 hydrogen atoms were included in the refinement.The absolute configuration was determined by computation of the R factors for the two possible configuration. Their structure factors were computed including the appropriate real and imaginary dispersion corrections for the atomic scattering factors of iodine for MoK_a radiation.