(19E)-3β,7β-Dihydroxy-17-oxoandrost-5-en-19-al 19-(O-carboxymethyl)oxime (26) was prepared in 15 steps from 17-oxoandrost-5-en-3β-yl benzoate (2, DHEA benzoate). Protection of position 17 by a borohydride reduction and acetylation, subsequent functionalization of position 19 by hypoiodite reaction, oxidation to 19-aldehyde and oximation gave successively (19E)-19-oxoandrost-5-ene-3β,17β-diyl 17-acetate 3-benzoate 19-(O-carboxymethyl)oxime methyl ester (10). Then 7-keto group was introduced by allylic oxidation with chromium(VI) oxide-3,5-dimethylpyrazole complex and stereoselectively reduced by borohydride in the presence of cerium(III) ions into 7β-hydroxy group. After protection as 7-isobutyrate the acetate at position 17 was removed and oxidation recovered 17-ketone. Final deprotection revealed both hydroxyl and carboxyl groups, giving desired 19-CMO 7β-hydroxy DHEA designed as hapten for immunassays.
(19E)-3β,7β-二羟基-17-酮基雄烯-5-烯-19-醛 19-(O-羧甲基)肟 (26) 是从17-酮基雄烯-5-烯-3β-基苯甲酸酯 (2,DHEA苯甲酸酯) 经过15步合成得到的。通过硼氢化物还原和乙酰化保护17位,随后通过假碘酸盐反应对19位进行官能化,氧化成19-醛并进行肟化,依次得到 (19E)-19-酮基雄烯-5-烯-3β,17β-二基 17-乙酸酯 3-苯甲酸酯 19-(O-羧甲基)肟甲酯 (10)。然后通过铬酸六价氧化物-3,5-二甲基吡唑配合物进行烯丙基氧化引入7-酮基团,并在三价铈离子存在下通过硼氢化物立体选择性还原为7β-羟基团。在保护为7-异丁酸酯后,去除17位的乙酸酯并进行氧化以恢复17-酮基。最终去保护揭示了羟基和羧基,得到期望的19-CMO 7β-羟基DHEA,设计为用于免疫分析的半抗原。