Structural studies of intermediates in the synthesis of mifepristone (RU 486). I. An 11β-substituted steroid

The title compound, 11β-[4-(dimethylamino)phenyl]-3,3-(ethylenedioxy)-17α-(1-propynyl)estra-9-en-5α, 17β-diol (C 31 H 41 NO 4 ), is the key intermediate in the synthesis of RU 486 and its overall conformation is similar to that of RU 486. The orientation of the (dimethylamino)phenyl ring, which seems to be connected with agonistic or antagonistic activity, is perpendicular to the steroid skeleton and is coplanar with C(9)−C(11). The separation [O(1)...O(3)] between the terminal O atoms is 10.27 A. The molecules are hydrogen bonded in a more or less head-to-tail fashion through H[O(3)] and O(4)