Racemic 2′-hydroxy-4′,4′-dimethylpyran-1,5-dihydroxyxanthone monohydrate

Abstract

The title xanthone (systematic name: 3,6,11-trihy­droxy-1,1-dimethyl-2,3-di­hydro­chromeno[2,3-f]chromen-7-one monohydrate), known as pruniflorone N, crystallized as a monohydrate, C18H16O6·H2O. The three ring systems of the xanthone skeleton are approximately coplanar, with an r.m.s. deviation of 0.0270 (1) Å from the plane through the 14 non-H atoms. The O atoms of the two hy­droxy substituents on the benzene rings also lie close to this plane, with deviations of 0.019 (1) and 0.070 (1) Å. The 2′-hy­droxy-4′,4′-di­methyl­pyran ring is disordered over two positions with a 0.798 (3):0.202 (3) site-occupancy ratio. An intra­molecular O—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, the xanthone and water mol­ecules are linked into a three-dimensional network by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions. π–π inter­actions, with centroid–centroid distances of 3.5982 (7), 3.6081 (7) and 3.6456 (7) Å, are also observed.