Neridienone A, a pregnane from the roots of Nerium oleander

In the title compound, 12β-hydroxy­pregna-4,6,16-triene-3,20-dienone, C₂₁H₂₆O₃, rings A and B are in almost half-chair conformations, ring C is in a chair conformation and ring D is in a 14α-envelope conformation. The A/B ring junction is quasi-trans, whereas the B/C and C/D ring junctions both approach trans character. The mol­ecule as a whole is slightly convex towards the β side. Intra- and inter­molecular hydrogen bonding, together with van der Waals inter­actions, plays a major role in the crystal structure.