The Structure of 16, 17β-epoxy-17α-pregn-5-en-3β-ol-20-one Monohydrate
Russian Chemical Bulletin
The structure of the title compound (1) has been studied by means of X-ray diffraction. The region of cycleD in epoxide1 was compared with that of the 16,17α-epoxy derivatives of progesterone and pregnenolone (studied previously) as well as with that of the respective 16,17α- and 16,17β-cyclopropano analogs. In contrast to the 16,17α-epoxy-20-oxo derivatives, in compound1 the electron conjugation of the epoxide ring with the CH3CO group at C(17) is partly disrupted. Moreover, the steric congestion at C(17) is significantly less pronounced in 16,17β-epoxide1 than in its 16,17α-counterpart. Both of these factors, especially steric decongestion, are favorable for nucleophilic attack at C(17) in the molecule of1. The X-ray diffraction data do not contradict the previously advanced mechanism of epoxide ring opening in 16,17α- and 16,17β-epoxy-20-oxo steroids by nucleophilic reagents.