Inclusion complexes of ketosteroids with β-cyclodextrin

Inclusion complexes of several steroid derivatives with β-cyclodextrin (7) were studied in dimethylsulfoxide solution. The investigated molecules were ketosteroids with different functional groups on the skeleton: 3β-acetoxypregn-5-en-20-one (1), 3β-acetoxypregna-5,16-dien-20-one (2), 3β-acetoxyandrost-5-en-17-one (3), 3β-hydroxyandrost-5-en-17-one (4), 5α-androstane-3,17-dione (5) and 17β-hydroxyandrost-4-en-3-one (6). Complex formation was monitored by two-dimensional ROESY experiments through the detection of intermolecular dipolar interactions. In case of inclusion complex formation, the steroid molecule penetrates the cavity of the cyclodextrin and dipole–dipole interactions (ROEs) can be detected between the glucose H-3 and H-5 protons inside the cyclodextrin cavity and the steroid skeletal protons. Intermolecular interactions were detected in all six cases. However, ROESY experiments provided data indicating only partial immersion (A and B ring of the steroid skeleton) in case of 1, 2 and 6. On the contrary, compounds 3 and 5, showing the most correlation rich spectra, seem to fully immerse in the β-cyclodextrin cavity.