Studies on a-norsteroids—VI : Directing effects of the C11-substituents on the addition of osmium tetroxide to steroidal Δ1,4-3-ketones

摘要: Abstract The effects of C11-substituents on the hydroxylation Δ1,4-3-oxosteroids with osmium tetroxide, have been examined. 11α-substituents, such as 11α-hydroxy, 1α-acetoxy or 11α-methyl-11β-hydroxy groups, result in selective addition tetroxide at Δ4 double bond, giving 4β,5β-dihydroxy-Δ1-3-oxosteroids. On other hand, 11-oxo yields exclusively 1α,2α-dihydroxy-Δ4-3-oxosteroids. Oxidation 1α,2α-dihydroxy-Δ4-3-oxosteroids having group manganese dioxide corresponding A-nor-Δ3(5)-1,2-dioxosteroids, which, however, tend to form hydrate C1-oxo group.