Altered selectivity of reduction of steroidal carbonyls

The reduction of steroidal ketones in different solvents yielded different products. These conditions which altered the normal path, yielded a selective reduction of the Δ⁴-3 carbonyl without the concomitant reduction of the C-17 or C-20 ketones; this permitted a one step partial synthesis of 3β-hydroxy-Δ⁴-pregnen-20-one (I), 3β-hydroxy-5-pregnan-20-one (II), and of 3β,11β-dihydroxyandrostan-17-one (IV).