Abstract
In order to clarify the effect of hydroxyls in 2-and 3-position on the progress of the Huang-Minlon reduction of metagenone, the Huang-Minlon reduction was carried out on 2, 3-dihydroxy-, 2-hydroxy-, and 3-hydroxy-25D, 5β-and 5α-spirostan-11-one, using tigogenone and hecogenin as comparative controls. It was thereby found that (1) reduction of ketone groups in 3-and 12-positions progresses 100%, (2) the reduction progresses in fairly high yield (69∼100%) in the case of 2, 3-dihydroxy-and 2-hydroxy-11-oxo compounds, and (3) in the case of 3-hydroxy-11-oxo compounds, the reaction hardly progresses with the exception of 3β-hydroxy-25D, 5α-spirostan-11-one. Reason for the ease or difficulty in the reduction of these substances cannot be explained fully as yet.
