Crystal and molecular structure of 20(S)-hydroxypregn-4-en-3-one [20(S)-hydroxyprogesterone]

Abstract

Crystals of the steroid 20(S)-hydroxyprogesterone are tetragonal, a= 9·422(1), c= 20·789(3)Å, Z= 4, space group P4₁. The structure has been determined by direct methods from diffractometer data and refined by full-matrix least-squares to a final R of 0·047 for 1462 observed reflections. All the ring junctions are trans/trans. The conformation of ring A is half-chair while that of rings B and C is chair. The cyclopentane ring D is a distorted C(13) envelope. The molecules are linked in the crystal structure ‘head-to-tail’ by a hydrogen bond between the C(20) hydroxy-group and the C(3) keto-group.