6 重原子を含む天然有機化合物の自動結晶解析に就て

抄録

The crystal structure of Adiantol B bromoacetate (I), Isozygosporin A mono-p-bromo-benzoate (II), and Silver polyetherin A (III) have been determined by X-ray diffraction methods. The crystal structures have been solved by a programme for the automatic heavy-atom analysis, written by Koyama and Okada for the C.D.C. 3600 computer, which leads from a heavy atom position to the positions of all atoms without any chemical assumptions. The programme consists of two parts and the first part (A part) selectes from the list of peak positions, which were stored in the computer, a set of atomic sites to be included in the next Fourier calculations. The second part (B part) selectes from the atoms, which were found in (A), a set of atomic sites to be inserted in the next cycle. Selection of the atomic sites in (A) is based on the "reasonable" interatomic distances (1.1〜1.7A) between neighbouring light-atom peaks, and that of (B) is based on the temperature factor (B>10.0A^2) only. The process can repeate cyclically till all atoms of the molecule will be determined. The programme will solve the structures in all triclinic, monoclinic, and orthorhombic space groups. The absolute configurations of Adiantol B bromoacetate, Isozygosporin A mono-p-bromo-benzoate, and Silver polyetherin A have been determined by the anomalous dispersion method.