Abstract Analogs of 7α-hydroxy-4-cholesten-3-one were prepared to ascertain structural features necessary for maximal activity of hepatic microsomal 12α-steroid hydroxylase. Methyl 3α, 7α-dihydroxy-5β-cholane-24-carboxylate derived from chenodeoxycholic acid was oxidized at C-3 with silver carbonate/Celite. The product was hydrolyzed and dehydrogenated with SeO 2 to provide 3-oxo-7α-hydroxy-4-cholene-24-carboxylic acid. ...