The crystal structure and molecular conformation of 2,2,6β-trichlorotestosterone acetate

Crystals of 2,2,6β-trichlorotestosterone acetate (C₂₁H₂₇O₃Cl₃) are monoclinic, space group P2₁, with unit cell dimensions a = 9·757 Å, b = 14·100 Å, c = 7·786 Å, β = 90·77°. The structure was solved by X-ray diffraction methods from the 3-dimensional Patterson and Fourier syntheses and was refined by block-diagonal least-squares to a final R of 0·09. The A-ring of the steroid molecule is found to be in the typical half-chair conformation in contrast to the half-boat conformation previously predicted from the interpretation of CD, ORD and NMR measurements.