Structural Studies of Intermediates in the Synthesis of Mifepristone (RU 486). III. 3,3‐Ethylenedioxy‐5(10),9(11)‐estradien‐17‐one

Crystallographic characterization of the title compound, C 20 H 26 O 3 , an intermediate in the synthesis of mifepristone (RU 486), has helped establish the molecular structure and its conformation. An uncommon C(14)-envelope conformation is observed in the five-membered ring due to the presence of a trigonal C atom. The molecules form continuous intermolecular C-H...O hydrogen-bonded chains arranged in a more or less zigzag shape along the b axis.