(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

Abstract

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.

Amaryllidaceae alkaloids: Absolute configuration and biological activity

“…The promising activity of 9 stimulated the development of an alternative improved extraction method to increase its yield from S. lutea Ker‐Gawl bulbs . The availability of 9 as a crystalline compound allowed the complete assignment of its 1 H and 13 C NMR spectra and to confirm its structure and absolute configuration by direct X‐ray analysis . Narciclasine ( 9 ), at ~1 μM in vitro and ~10 mg/kg in vivo, displays marked proapoptotic and cytotoxic activity, as does pancratistatine, albeit also showing severe toxic side effects.…”