Structure of 3α,12β-dihydroxy-2β-morpholino-5α-pregnan-20-one, C₂₅H₄₁O₄N

The crystal and molecular structure of 3 α,12 β-dihydroxy-2 β-morpholino-5α-pregnan-20-one, C₂₅H₄₁O₄N, has been determined:M_r=419.6, P2₁, a=13.5778(8), b=14.4340(8), c=5.8943(5) Å, β=94.32(1)°, V_c=1151.9(3) ų, Z=2, D_x=1.21 g cm^-3, {Mathematical expression}(Cu Kα) = 1.5418 Å, μ=5.6 cm^-1, F(000)=460, R=0.039, R_w=0.040 for 2421 unique observed reflections. All six-membered rings have chair conformations, and the D ring has a 13 β-envelope conformation. The progesterone side chain has an unusual conformation, and the C16-C17-C20-O20 torsion angle, which defines the conformation, is -152.6(3)°. The unusual conformation seems to be forced by the intramolecular hydrogen bond between the hydroxyl group at C12 and the O20 atom from the side-chain.