Structure of 6-methylene-4-pregnene-3,20-dione

C22H30O2 (1), Mr = 326.47, orthorhombic, P2(1)2(1)2(1), a = 9.662 (3), b = 23.32 (7), c = 8.167 (2) A, V = 1840.3 (4) A3, Z = 4, Dx = 1.178 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 5.34 cm-1, F(000) = 712, T = 293 K, R = 0.035, wR = 0.044, S = 1.954 for 2147 unique observed reflections with Fo greater than 2 sigma(Fo). Rings B and C have chair conformations, the A ring assumes an intermediate sofa-half-chair conformation, and the D ring is in the half-chair conformation. The progesterone side chain has the same conformation as observed in 81 steroids; the C16-C17-C20-O20 torsion angle is -18.9 (3) degrees; the C4-C5-C6-C6M torsion angle is -48.6 degrees.