Crystal Structure and Conformational Analysis of 3β,17β-Diacetoxy-8,9-seco-5α-androstane-8,9,11-trione

Abstract

Abstract The crystal and molecular structures of the title compound 1 have been determined by direct methods. The crystals are monoclinic, space group P21, with a = 12.512(2), b = 7.436(2), c = 12.252(2) Å, β = 102.62(1)°, Z = 2. The structure was refined by full-matrix least-squares calculations to a final R of 0.056 for 2268 independently observed reflections. This tricylic compound consists of five-, six-, and ten-membered rings and is slightly bent, including two OAc side chains. The six-membered ring A has a typical chair conformation and the ten-membered ring B adopts a chair-chair conformation. Ring C is a normal β envelope. The ring junctions of both A/B and B/C are trans fusion. Two double bonds [C(8)=O(2), C(11)=O(4)] and two methyl groups [C(18), C(19)] of ring B are oriented α face, and one double bond [C(9)=O(3)] is on the β face of this ring. The O–C–O bond distances in the OAc side chains show partial double-bond characters.