A comparative structural study on the steroids [1,2,5]oxadiazolo[3', 4':3,4]-5 alpha-pregn-16-en-20-one oxime (HS998), [1,2,5]oxadiazolo[3, 4':3,4]-5 beta-pregn-16-en-20-one (HS973) by NMR, molecular modeling, and X-ray investigations.

The molecular structure of the steroids [1,2,5]oxadiazolo[3', 4':3,4]-5 alpha-pregn-16-en-20-one oxime, [1,2,5]oxadiazolo[3',4':3, 4':3,4]-5 alpha-pregn-16-en-20-one and [1,2,5]oxadiazole]3',4':3,4]-5 beta-pregn-16-en-20-one has been determined. The proton-proton distances in the solid state from previous crystallographic studies are compared with the corresponding distances from novel and previous solution NMR as well as from novel in vacuo modeling studies.