Crystal and molecular structure and absolute stereochemistry of cularine methiodide

Abstract

The structure of cularine has been determined by three-dimensional X-ray diffraction analysis of its methiodide. Crystals are monoclinic, with Z= 4 in a unit cell of dimensions: a= 22·31(5), b= 8·43(12), c= 11·71(9)Å, β= 90·9(1)°, space group P2₁. The structure was solved from photographic data by the heavy-atom method and refined by least-squares to R 0·100 for 1416 observed reflexions. The absolute configuration has been determined by the method of anomalous dispersion as L(S). On the basis of this work all cularine-type alkaloids also have the L(S)configuration.