Crystal structure and absolute configuration of guan-fu G base methyliodide

Guan-fu base G is a new alkaloid isolated from root tuber of Aconitum coreanum Le'vl Raipaics. Guan-fu base G methyliodide crystallizes in orthorhombic system, space group D4/2-P212121, with dimensions: a = 16.87A, b = 16.93A, c = 10.09A; Z = 4. The three dimensional data were collected on a Phillips PW-1100 four-circle diffractometer with Mo Ka radiation. The structure was solved by heavy-atom method and subsequently successive Fourier syntheses. The structure was refined by block-diagonal matrix least squares methods to R = 0.0578 for 2848 reflexions. The absolute configuration was determined by computation of the R factor for the two possible configurations using anomalous scattering of iodine.