| abstract |
A method is provided for isolating 5,7-diene-containing steroids, particularly 3 β-ols and esters of 3 β-ols, from a sterol mixture. The method involves (1) treating the mixture with a dienophile or with an oxidizable dienophile precursor in combination with an oxidizing agent so as to provide a Diels-Alder adduct of the 5,7-diene to be isolated, followed by (2) removal of the adduct from the mixture and (3) regeneration of the 5,7-diene with a suitable reducing agent. The invention also encompasses subsequent purification steps and intermediate modification of the Diels-Alder intermediate, e.g., wherein chemical conversion of the Diels-Alder adduct is effected prior to regeneration of the 5,7-diene. Novel compounds which are Diels-Alder adducts of 5,7-diene-containing steroids are provided as well. |