13C nuclear magnetic resonance studies. 85. 13C spectra of several ring-contracted and -expanded steroids

The 13Cmr spectra of several cholestanes including 13 A-homo-B-nor derivatives, 11 A-homo derivatives, and 8 B-nor examples have been examined. In addition the 13C data for a few of the corresponding androstanes and 16 precursors in the cholestane series are reported. Examples in both the 5α- and 5β-cholestane families were included. These results represent the first systematic examination of the 13C spectra of A-homo-B-nor steroids and should be useful for the characterization of other members in each series. These data also permit some tentative conclusions regarding the favored conformation for the seven-membered ring in the A-homo derivatives.