Acta Cryst. (2008). E64, o713  [ doi:10.1107/S1600536808006867 ]

Alpinumisoflavone

J. J. E. K. Harrison, Y. Tabuchi, H. Ishida and R. Kingsford-Adaboh

Abstract: The title compound, C₂₀H₁₆O₅, {systematic name: 5-hydroxy-7-(4-hydroxyphenyl)-2,2-dimethyl-2H,6H-benzo[1,2-b:5,4-b']dipyran-6-one}, was obtained by demethylation of the biologically active related compound, 4-O-methylalpinumisoflavone. The molecular structure of the title compound is characterized by a fused tricyclic system that contains an approximately planar benzopyrone ring fragment. The six membered pyran ring adopts a half-chair conformation. Both ring systems show an out-of-plane twist. The dihedral angle between the mean plane of the benzopyrone system and the benzene ring is 54.29 (3)°. The molecules are linked by O-HO hydrogen bonds, forming a molecular tape running along the b axis.

Online 14 March 2008

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