On steroids .388. Synthesis of (19E)-3 beta,7 beta-Dihydroxy-17-oxoandrost-5-en-19-al 19-(O-carboxymethyl)oxime, new hapten for 7 beta-hydroxy-dehydroepiandrosterone (3 beta,7 beta-dihydroxyandrost-5-en-17-one)

(19E)-3 beta,7 beta-Dihydroxy-17-oxoandrost-5-en-19-al 19-(O-carboxymethyl)oxime (26) was prepared in 15 steps from 17-oxoandrost-5-en-3 beta-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-3 beta,17 beta-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 7 beta-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 7 beta-hydroxy DHEA designed as hapten for immunassays.