Synthesis of (15E)-17β-hydroxyandrost-4-ene-3,15-dione 15-(O-carboxymethyl)oxime, a potential hapten for testosterone immunoassays

摘要

The key intermediate, 15-oxandrost-5-ene-3β,17β-diyl 3-acetate 17-benzoate (10), was prepared by a five-step procedure based on the addition of 4-methoxybenzyl alcohol to 3β-hydroxyandrosta-5,15-dien-17-one (1). The resulting C-15 isomers were separated as acetates. In both series, the 17-ketones were reduced to 17β-hydroxy derivatives, and after benzoylation, the protecting methoxyphenylmethyl group at position 15 was removed with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, leaving 15β-hydroxyandrost-5-ene-3β,17β-diyl 3-acetate 17-benzoate (6) and its 15α-isomer 9. After Jones oxidation, both benzoates afforded the identical ketone 10. The reaction of 10 with (O-carboxymethyl)hydroxylamine in pyridine followed by diazomethane esterification gave (15E)-15-oxandrost-5-ene-3β,17β-diyl 3-acetate 17-benzoate 15-(O-carboxymethyl)oxime methyl ester (11). Methyl ester 11 was successively submitted to acidic deacetylation, Oppenauer oxidation, potassium hydroxide treatment, and reesterification with diazomethane to give (15E)-17β-hydroxyandrost-4-ene-3,15-dione 15-(O-carboxymethyl)oxime methyl ester (14). After purification, ester 14 was hydrolyzed with potassium hydrogen carbonate in aqueous methanol at elevated temperature into free testosterone 15-(O-carboxymethyl)oxime (15).