Metal Ion Catalyzed Oxidation of Steroids. II. Oxidation of Cholesterol by Fenton's Reagent in Acetic Acid Solution

Abstract

When cholesterol (I) was treated with the hydrogen peroxide-ferrous sulphate system in an acetic acid solution, there were formed 5α-cholestane-3β, 5, 6β-triol (II), 3β-acetoxy-5α-cholestane-5, 6β-diol (III), 5, 6α-epoxy-5α-cholestan-3β-ol (IV), 6β-acetoxy-5α-cholestane-3β, 5-diol (V), and 3β, 6β-diacetoxy-5α-cholestan-5α-ol (VI). Ferrous ions accelerated remarkably the formation of these products (Fig. 2) as well as peracetic acid (Fig. 3). The same ions were, however, likely to be independent of forming the epoxide (IV) from I with peracetic acid (Fig. 4). Hydrogen peroxide and ferrous ions were cooperative in facilitating the formation of II from IV, conrtary to be entirely invalid in their independent use (Fig. 5). Thus, it seemed in the present reaction that the epoxide (IV) is produced heterolytically, as usual, with peracetic acid which can easily be formed in the mixture of acetic acid and hydrogen peroxide (Chart 1) and that the triol (II) as well as the derivatives (III, V, and VI) are formed mainly through IV.