Crystal structure of 17β-hydroxy-17α-methyl-5α-androstano [2,3-C] Furazan (Furazabol)

The crystal and molecular structure of 17β-hydroxy-17α-5α-androstano [2,3-C] Furazan, Furazabol (C20H24N2O2), has been determined by direct methods and refined by full matrix least squares to a final R of 0.0528 for 1927 observed reflections and 216 parameters, CuKα, λ = 1.54178 A. The compound crystallizes with two molecules in the asymmetric unit, Z = 4, Dc = 1.131 Mg m−3 space group P21, with unit cell parameters a = 18.747(3), b = 6.346(5), c = 15.647(4) A, β = 99.96(2)°, V = 1833.9 A3, μ(CuKα) = 0.584 mm−1. Whilst the two independent molecules have similar overall geometry there are small differences in bond lengths, bond angles and torsion angles in rings A and D and significant conformational differences in ring A. The A ring adopts a half-chair conformation in molecule A and an intermediate between a half-chair and a sofa in molecule B. The D ring in molecule A has a 13β/14α half-chair conformation and in molecule B a conformation between an envelope and half-chair.