The crystal and molecular structure of a brominated compound derived from paeoniflorin

Abstract

The crystal structure of the brominated compound, C35Ha9OisBr, has been determined in order to confirm the molecular structure and to determine the absolute configuration of paeoniflorin, C23H28Olb a monoterpene glucoside isolated from Paeonia albiflora Pallas. The crystals are orthorhombic with space group P2~2121 and the unit cell dimensions are a= 13.58, b= 21.74, c= 12.61/1,; Z=4. The crystal structure was solved by the heavy atom method and refined by the block-matrix least-squares method. The final R value for 1844 observed reflexions was 0.107. The molecular structure of paeoniflorin deduced from the present X-ray study of the brominated compound was in complete agreement with the proposed structure, a novel glucoside of a monoterpene of the pinane group. The absolute configuration was determined by the use of the anomalous dispersion effect of the bromine atom for Cu K~ radiation, which is compatible with the fact that the glucosidic residue is of D-glucose.