抄録
(25R)-Spirost-5-en-3 β-acetate (C29H44O4) crystallizes in monoclinic space group P21 with a = 14.559(2), b = 6.212(3), c = 14.847(7)Å; β = 100.22(2)°, Z = 2, Dcal = 1.148 Mg/m3. The structure was solved by direct methods and refined by full-matrix least-squares procedures to a final R-value of 0.0513 for 2176 observed reflections. The six-membered A, C and F rings adopt the chair conformation, whereas rings B and D are in the half-chair conformation. Ring E is in the envelope conformation. The A/B ring junction is quasi-trans, while ring junctions B/C and C/D are trans fused about the C8-C9 and C13-C14 bonds, respectively. The D/E ring junction is cis. The molecule is slightly convex towards the β side, with an angle of 10.7(2)°. Cohesion of the molecules in the unit cell can be attributed to van der Waals interactions.
