On reduction of α,β-unstaurated ketones and the respective allylic alcohols, bearing a phenylsulfonyl or phenylsulfanyl group in the α position. Hydroxy group-controlled stereoselective reduction of 3α- and 3β-hydroxy-4-(phenylsulfonyl)cholest-4-ene
cholestane 7a, respectively. Reduction of 4-(phenylsulfonyl)cholest-4-en-3-one 2 with lithium aluminohydride yields compound 8. Reduction of compounds 2, 13a and 15a with other metal hydrides affords mixtures of diastereomeric products. Metal hydridereductions of 4-(phenylsulfanyl)cholest-4-en-3-one 1 affect the carbonyl group only. Catalytic hydrogenation of compound 2 gives a mixture of 5α- and