Abstract N-Acetylation of solasodine gives only one rotameric N-acetyl derivative compared with N-acetyl-3-methylpiperidine, which exists in solution as two equally populated rotamers. The 1 H and 13 C NMR spectra (CDCl 3) of O, N-diacetyl-and O-acetyl-N-benzoylsolasodine indicate significant deviations from F-ring chair geometry. Opening of the F ring of these derivatives in CDCl 3 solution at 25 C, to give the corresponding furosta-5, 20 (22)-diene ...