Suggested Reaction 1.1.4.-

Left

17alpha,21-Dihydroxy-4-pregnene-3,11,20-trione
+1,4-Dithiothreitol

Right

11beta,17alpha,21-Trihydroxy-4-pregnene-3,20-dione
+Oxidized dithiothreitol

[BiSSCat | GREP ]