The crystal structure of a potent anti-androgen: cyproterone acetate (6-chloro-17-hydroxy-1α,2α-methylenepregna-4,6-diene-3,20-dione acetate)

The crystal structure of the anti-androgen cyproterone acetate (CPA, 6-chloro-17-hydroxy-le,2emethylenepregna-4,6-diene-3,20-dione acetate, C24H2904C1) was determined with the aid of symbolic addition. The steroid crystallized in the orthorhombic space group P212121 with a= 10.757 (2), b= 12.266 (3), e-16.623 (3) A,, and Z=4. A three-dimensional data set was collected with Cu Ke radiation (2= 1.5418 A,) on a Syntex P1 diffractometer to a maximum 20 value of 100 ° employing a 0-20 scan technique. The coordinates of the non-hydrogen atoms and their anisotropic temperature factors were refined in a full matrix least-squares manner to a final R index of 0.054 based on F 2. Bond distances around the cyclopropane ring were shortened, implying an interaction with the carbonyl group in ring A.