The Course of the Catalytic Hydrogenation/Isomerization Reaction of Steroidal Ring B Olefins in the 13β‐ and 13α‐Series

The course of the catalytic hydrogenation and isomerization (H 2 / Raney ‐Ni/dioxane or H 2 /Pd/C/EtOH) of Δ 5.7 ‐, Δ 7 ‐, Δ 8 ‐, and Δ 8(14) ‐steroid olefins was shown to depend strongly on the configuration at C(13). The known hydrogenation/isomerization of reactions of Δ 5.7 ‐dienes in the 13β‐series to Δ 7 ‐(H 2 / Raney ‐Ni/dioxane) and Δ 8(14) ‐olefins (H 2 /Pd/C/EtOH) were also confirmed in the 3β, 19‐epoxy‐13β‐ and 3‐Oxo‐19‐acetoxy‐13β‐steroid series (e.g. 32 → 35 → 37 , Scheme 3 ). On the other hand, in the corresponding 13α‐steroid series the same reactions afforded the Δ 7 ‐. and the Δ 8 ‐olefins (mixture of products with H 2 / Raney ‐Ni/dioxane; quantitatively the Δ 8 ‐compounds with H 2 /Pd/C/EtOH; s. e.g. Scheme 3 ). A similar dependence on the C(13) configuration was observed in the allylic oxidation of these olefins with SeO 2 ( Fieser's test, see Table ), and in the acid catalyzed opening of the 7α, 8α‐epoxides ( e.g. 60 → 62 + 63 in the 13β‐series, and 56 → 64 + 65 in the 13α‐series, Scheme 8 ).