Crystal structure of picropodophyllin

The crystal and molecular structure of the title compound, C22H21O8, has be en elucidated at room temperature by single crystal X-ray diffraction techn ique. The colorless crystals are orthorhombic, space group P2(1)2(1)2(1), w ith unit cell parameters a = 10.538(1) Angstrom, b = 11.203(1) Angstrom, c = 16.855(2) Angstrom, Z = 4, D-c = 1.380 g cm(-3) The structure was solved by direct methods and refined by a full-matrix least-squares procedure to f inal R = 0.042 for 1241 observed reflections with I greater than or equal t o 3 sigma(I). The structure of the molecule consists of a fused ring system containing four (A, B, C and D) rings with a pendant methoxy phenyl (E) ri ng. The conformations of dioxolen (A) ring, both phenyl (B and E) rings, th e cyclohexane (C) ring and the lactone (D) ring are envelope, planar, disto rted boat and envelope, respectively. The plane of the phenyl (E) ring is a bout 72 degrees from the mean least-squares plane of rings A, B, C and D. T he molecules are connected in a head to tail fashion by O-H...O hydrogen bo nds.