Journal article, 2005
The synthetic steroid 21-acetoxy-17α-4-pregnene-3,20-dione, C 23H32O4, 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.