3,17-Dioxoandrost-4-en-4-yl acetate.

The title compound, C(21)H(28)O(4), has a 4-acetoxy substituent positioned on the steroid alpha face. The six-membered ring A assumes a conformation intermediate between 1alpha,2beta-half chair and 1alpha-sofa. A long Csp(3)-Csp(3) bond is observed in ring B and reproduced in quantum-mechanical ab initio calculations of the isolated molecule using a molecular-orbital Hartree-Fock method. Cohesion of the crystal can be attributed to van der Waals interactions and weak C-H...O hydrogen bonds.