Structure of 17β-hydroxy-4-pregnen-20-yn-3-one, C₂₁H₂₈O₂

The crystal structure of 17 β-hydroxy-4-pregnen-20-yn-3-one, C₂₁H₂₈O₂, was determined by means of X-ray diffraction methods. M_r=312.5, space group P2₁, a=6.493(1), b=21.065(3), c=6.478(1) Å, β=105.97(1)°, V_c=851.9(3) ų, Z=2, D_x=1.22 Mg m^-3, Cu Kα radiation (λ=1.54184 Å), μ(Cu Kα)=5.5 cm^-1, F(000)=340. The structure was solved with Multan; final conventional R=0.032 (R_w=0.032) for 1803 reflections. The molecule studied (I) has an overall conformation almost identical to 19-norethindrone (II), although ring A of molecule (I) is slightly more bent toward the α direction of the steroid skeleton in comparison with molecule (II).