(2S,3R,4S,4aR)-2,3,4,7-Tetra­hydroxy-3,4,4a,5-tetra­hydro­[1,3]dioxolo[4,5-j]phenanthridin-6(2H)-one hemihydrate

The title natural compound, isolated from Narcissus pseudonarcissus var. King Alfred crystallizes as a hemihydrate, C₁₄H₁₃NO₇·0.5H₂O, with four crystallographically independent dioxolophenanthridinone mol­ecules and two crystallographically independent solvent water mol­ecules in the asymmetric unit. All four crystallographically independent dioxolophenanthridinone mol­ecules are geometrically very similar and differ only in the orientations of the three hy­droxy groups at the terminal cyclo­hexene rings. The five-membered dioxolane ring has a planar conformation (the r.m.s. deviations are 0.010, 0.019, 0.025 and 0.004 Å, for the four crystallographically independent molecules), and the six-membered dihydro­pyridone and cyclo­hexene rings adopt sofa conformations in each mol­ecule. The flattened structure of each dioxolophenanthridinone mol­ecule is supported by a strong intra­molecular O—H...O hydrogen bond. The N atom has a slightly pyramidalized configuration. In the crystal, the dioxolophenanthridinone mol­ecules form layers parallel to (101) with O—H...O and N—H...O hydrogen bonds linking the dioxolophenanthridinone mol­ecules both within and between the layers and the water mol­ecules, forming a three-dimensional framework. The absolute configurations of the chiral centers are 2S, 3R, 4S and 4aR.