Crystal Structure of (6aR,11aR)-4,9-dimethoxy-3-hydroxypterocarpan

(6aR,11aR)-4,9-dimethoxy-3-hydroxypterocarpan was isolated from the natural plant of Caragana spinifera Kom (Leguminosae). The structure was elucidated by infrared spectra(IR), mass spectrometry(MS), 1H-Nuclear magnetic resonance(1H-NMR),13C-Nuclear Magnetic Resonance(13C-NMR), 1H-1H correlation spectroscopy(1H-1H COSY), heteronuclear multiple quantum coherence(HMQC) and heteronuclear multiple bond coherence(HMBC). In addition, its crystal structure was determined by the single-crystal X-ray diffraction analysis. It crystalized in monoclinic, space group P21 with a=6.4778(13), b=12.631(3), c=8.8368(18)(A), β= 95.8(3)o, C17H16O5, Mr=300.30, V=719.3(3)(A)3, Z=2, Dc=1.386 Mg/m3, F(000)=316, μ=0.102 mm-1, the final R=0.0332 and wR=0.0862 for 1533 observed reflections (I>2σ(I)). The molecular backone of the compound includes a benzofuro and a benzopyran. The X-ray analysis shows that the absolute configuration of the compound is cis-pterocarpan.