Abstract
16β-Ethyl-17β-hydroxyestr-4-en-3-one (oxendolone) (1), a new antiandrogen, was synthesized starting from dehydroepiandrosterone (2). 3β-Acetoxy-16β-ethylandrost-5-en-17β-ol (3), prepared from 2 by stereospecific introduction of 16β-ethyl substituent, was converted into 3β, 17β-diacetoxy-5α-chloro-16β-ethyl-androstan-6β-ol (5) by acetylation and then chlorohydrination. Treatment of 5 with lead tetraacetate gave 3β, 17β-diacetoxy-5α-chloro-16β-ethyl-6β, 19-oxidoandrostane (6) in 96% yield. 6 was transformed into 17β-acetoxy-16β-ethyl-6β, 19-oxidoandrost-4-en-3-one (8) by two steps. Reductive cleavage of an oxido bond of 8 with zinc followed by oxidation with pyridinium chlorochromate yielded 17β-acetoxy-16β-ethylandrost-4-ene-3, 19-dione (10) in 75% yield. Treatment of 10 with sodium hydroxide followed by acid hydrolysis gave 1 in good yield.
