21-Acet­oxy-17α-4-pregnene-3,20-dione

The synthetic steroid 21-acet­oxy-17α-4-pregnene-3,20-dione, C₂₃H₃₂O₄, crystallizes with a single mol­ecule in the asymmetric unit. The mol­ecule contains four fused rings, typical of steroids. The cyclo­hexene ring A has nearly the conformation of a boat. One saturated six-membered ring, B, is inter­mediate between chair and half-chair conformations, while the other six-membered ring, C, is essentially a chair. The five-membered ring D tends towards a twist conformation. The ring junction A/B is quasi-trans, whereas the ring junctions B/C and C/D are both trans. The mol­ecule is slightly convex towards the β side.