Racemic 2'-hydroxy-4',4'-dimethylpyran-1,5-dihydroxyxanthone monohydrate.

3,6,11-trihy-droxy-1,1-dimethyl-2,3-di-hydro-chromeno[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 hy-droxy substituents on the benzene rings also lie close to this plane, with deviations of 0.019 (1) and 0.070 (1) Å. The 2'-hy-droxy-4',4'-di-methyl-pyran ring is disordered over two positions with a 0.798 (3):0.202 (3) site-occupancy ratio. An intra-molecular O-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, the xanthone and water mol-ecules are linked into a three-dimensional network by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions. π-π inter-actions, with centroid-centroid distances of 3.5982 (7), 3.6081 (7) and 3.6456 (7) Å, are also observed.