dl-17 beta-hydroxy-8 alpha-androst-4-en-3-one (8-isotestosterone)

The molecular conformation of dl-8-isotestosterone has been determined crystallographically. Crystals of the title compound belong to the space group P21/c with a = 11.449(4), b = 10.962(4), c = 25.860(5) A, beta = 100.95(4)o, with two molecules in the asymmetric unit. The structure has been refined to a final R value of 0.052 for 2227 reflections. Unlike testosterone, which is a flat molecule, its 8-isomer has a folded conformation. The conformations of the ring-B in the two crystallographically independent molecules (A and B) corresponded to the twist form and differ significantly from one another.