Ikegawa S, Kurosawa T, Tohma M
Faculty of Pharmaceutical Sciences, Higashi-Nippon-Gakuen University, Hokkaido, Japan.
Steroids. 1990 Jun;55(6):250-5. doi: 10.1016/0039-128x(90)90039-e.
4-Hydroxyequilin, 4-hydroxyequilenin, and 16 alpha-hydroxyequilenin were synthesized as authentic specimens for the metabolic studies of equine estrogens. The synthetic route leading to the 4-hydroxylated compounds was started from o-vanillin, which was transformed into the beta-ketosulfoxide (2b) by sequential multistep reactions. This was converted to the alpha,beta-unsaturated ketone (3) as Michael acceptor. Condensation of 3 with 2-methylcyclopentane-1,3-dione, followed by ring closure with methanesulfonic acid provided the cyclized estrapentaene (5). Several oxidoreduction reactions were then performed to give the desired compounds. Preparation of 16 alpha-hydroxyequilenin was attained by reductive cleavage of the 16 alpha,17 alpha-epoxide formed from equilenin.
