Oxidation of natural targets by dioxiranes. Part 6: on the direct regio- and site-selective oxyfunctionalization of estrone and of 5α-androstane steroid derivatives

Using methyl(trifluoromethyl)dioxirane (1b), 3β,6α,17β-triacetoxy-5α-androstane (6) could be selectively transformed into its C-14 hydroxy derivative (7) and into the valuable C-12 ketone steroid (8), in high yields under mild reaction conditions. Similarly, the oxidation of 3α-estrone acetate (4) with 1b was carried out to yield selectively the steroid C-9 hydroxy derivative (5). The high regio- and site-selectivity attained demonstrates that the powerful dioxirane 1b is the reagent of choice to synthesize valuable oxyfunctionalized steroid derivatives.