Die Röntgenstrukturanalyse von 17β‐Bromacetoxy‐ 9β, 10α‐androst‐4‐en‐3‐on

The structure of 17β‐bromacetoxy‐9β, 10α‐androst‐4‐en‐3‐one has been determined by three‐dimensional X‐ray crystallographic methods. The crystals of the restrosteroid belong to the orthorhombic space group P 2 1 2 1 2 1 with four molecules per unit cell. The cell constants are a = 11.32 Å, b = 13.71 Å and c = 12.52 Å. The absolute configuration of the molecule has been determined by the anomalous dispersion method. Bond length, bond angles and distances of atoms from ‘best planes’ are given. Ring A represents a distorted half‐chair, ring B and C a chair and ring D an envelope conformation. The molecule shows, contrary to normal 9α, 10β‐steroids, a bent shape.