Volume 52 (1979) Issue 3 Pages 677-683
The structures of 6-deoxyversicolorin A, C18H10O6, and versicolorin A, C18H10O7, both isolated from Aspergillus versicolor, have been determined by the X-ray diffraction method. Both compounds crystallized in the space group P212121, with four molecules per unit cell. The cell dimensions of 6-deoxyversicolorin A are a=9.588, b=18.083, c=7.769 Å, and those of versicolorin A are a=9.524, b=18.629, c=7.629 Å. The structure was refined to R=0.055 for 6-deoxyversicolorin A and to R=0.043 for versicolorin A. Both structures are in agreement with those assigned by chemical and spectroscopic methods. There are two intramolecular hydrogen bonds in each molecule. Although an intermolecular hydrogen bond is present in versicolorin A, both structures are isotypic. The dimensions of the anthraquinone skeleton and the dihydrofuro[2,3-b]furan moiety are compared with those in related compounds whose structures have been determined.