Preparation of tritium‐labeled compounds. V. A group of steroids by catalytic reduction of unsaturated precursors with tritium gas

A group of Δ 4 ‐3‐keto steroids was prepared by catalytic reduction of suitable conjugated diene‐3‐keto precursors with tritium gas. Thus, 11α‐hydroxy‐4‐pregnene‐3,20‐dione‐7‐ 3 H (I), 20α‐hydroxy‐4‐pregnen‐3‐one‐7‐ 3 H (II), 6α‐methyl‐4‐pregnene‐3,11,20‐trione‐7‐ 3 H (III), 17α‐hydroxy‐6α‐methyl‐4‐pregnene‐3,20‐dione‐7‐ 3 H, acetate (IV), and 17α‐hydroxy‐6‐methyl‐ 3 H 3 ‐16‐methylenepregna‐4, 6‐diene‐3,20‐dione, acetate (V) were prepared from 11α‐hydroxypregna‐4,6‐diene‐3,20‐dione (VI), 20α‐hydroxypregna‐4,6‐dien‐3‐one (VII), 6‐methylpregna‐4,6‐diene‐3,11,20‐trione (VIII), 17α‐hydroxy‐6‐methylpregna‐4,6‐diene‐3,20‐dione, acetate (IX), and 17α‐hydroxy‐6‐dibromomethylene‐16‐methylene‐4‐pregnene‐3,20‐dione, acetate (X), respectively. In addition, 3α‐hydroxy‐5β‐pregnane‐11,20‐dione‐7‐ 3 H, cyclic 20‐(trimethylene acetal) (XI) was prepared from I via 11α‐hydroxy‐5β‐pregnane‐3,20‐dione‐7‐ 3 H (XII), 5β‐pregnane‐3,11,20‐trione‐7‐ 3 H (XIII) and 3α‐pregnane‐11,20‐dione‐7‐ 3 H (XIV).