Regiospecific syntheses of modified steroid hormones. Part V. 6β-Fluoro-7α-hydroxy-17β-oestradiol, 7α-fluoro-6α-hydroxy-17β-oestradiol, and 7α-fluoro-17β-oestradiol

Abstract

6β-Fluoro-7α-hydroxy-17β-oestradiol 3,17-diacetate (3a) was obtained by reaction of hydrogen fluoride with 6α,7α-epoxy-17β-oestradiol diacetate (2). Oxofluorination of oestra-1,3,5(10),6-tetraene-3,17β-diol diacetate (1b) gave 7α-fluoro-6-oxo-17β-oestradiol diacetate (4b), which was reduced stereoselectively to 7α-fluoro-6α-hydroxy-17β-oestradiol 3,17-diacetate (5a). Conversion of the 6α-ol (5a) into the 6-methanesulphonate (5b), followed by reaction with lithium aluminium hydride, gave 7α-fluoro-17β-oestradiol (6a).