INCLUSION COMPLEXES OF THE NATURAL PRODUCT GOSSYPOL - CLATHRATE TYPE INCLUSION COMPLEXES OF GOSSYPOL WITH CARBONYL GROUP CONTAINING GUESTS

The crystal structures of 2:1 inclusion complexes of gossypol with methyl propionate (GPMEP) and ethyl acetoacetate (GPEAA) have been determined by X-ray structure analysis. The crystals of GPMEP, C30H30O8″″l/2 C4H8O2, are monoclinic, space group C2/c, a=11.079(3), b = 30.724(7), c = 16.515(5) Å, β = 90.46(2)°, V = 5621(3) Å, Z = 8, Dx = 1.33 g cm-3. The structure has been refined to the final R value of 0.059 for 1899 observed reflections. The crystals of GPEAA, C30H30O8″″l/2 C6H10O3, are monoclinic, space group C2/c, a=11.095(2), b=30.604(9), c = 16.955(5) Å, β = 88.27(2)°, V = 5754(3) Å, Z = 8, Dx = 1.35 g cm-3. The structure has been refined to the final R value of 0.056 for 2502 observed reflections. In contrast to previously investigated inclusion complexes of gossypol the host molecules do not form centrosymmetric dimers via hydrogen bonds. In the crystal structures the racemic gossypol is separated into enantiomers forming alternating bimolecular layers. Nearly perpendicular to these chiral bilayers run elongated cavities enclosed on each side by layers of opposite chirality. The surface of these layers is hydrophobic, the polar groups are hidden inside the layer. Guest molecules which are hydrogen bonded to the host are included in cylindrically shaped cavities. Possible hydrogen bonds between host and guest are analysed for this isostructural class of complexes. © 1990 Kluwer Academic Publishers.