Studies on conformation and reactivity. Part XII. Acetolysis and stereospecific rearrangement of 4-bromocholest-4-en-3-one

Abstract

Treatment of 4-bromocholest-4-en-3-one (I) with potassium acetate in boiling acetic acid affords a mixture containing the product of normal displacement at C(4)[4-acetoxycholest-4-en-3-one (IV)], products of S_K2′ displacement at C(6) and C(2)[6β-acetoxy-(VII)(major product) and 2α-acetoxy-(V) cholest-4-en-3-ones], and 4-hydroxycholest-4-en-3-one (II), cholesta-4,6-dien-3-one (III), and 5α-cholestane-3,6-dione (VI). Treatment of bromo-enone (I) with potassium acetate in absolute ethanol gives the 4-acetoxy-compound (IV) as the major product, two 6β-substituted products [(VII) and 6β-ethoxycholest-4-en-3-one (VIII)], the 4-hydroxy-compound (II), cholest-4-en-3-one (IX), 4-(3-oxocholest-4-en-4-yloxy)cholesta-4,6-dien-3-one (X), and an unidentified substance.