11B-FLUORO-3-ACETOXYESTRA-3,5-DIEN-17-ONE AND METHOD FOR THE PRODUCTION THEREOF
The present invention relates to 11β-fluoro-3-acetoxyestra-3,5-dien-17-one as a suitable intermediate in the preparation of 11-fluoro-substituted steroids and to the process for preparation thereof. For this purpose, 11α-hydroxyestra-4-ene-3,17-dione is reacted with 1 to 3 equivalents of n-nonafluorobutanesulfonyl fluoride and 3 to 5 equivalents of diazabicycloundecene (DBU) at −40 to −20° C. in an organic aprotic solvent and, after an aqueous workup, reacted with 5 to 10 equivalents of acetic anhydride and 0.01 to 1 equivalent of a strong acid. The desired product precipitates spontaneously out of the reaction solution and is obtained in a very high purity by filtration. The process is notable for the very high yield, avoidance of a chromatographic purification of the product, a reduced proportion of wastes and significantly increased process throughput. The process according to the invention is therefore especially suitable for preparing 11β-fluoro-3-acetoxyestra-3,5-dien-17-one on a large industrial scale.
1 . 11β-Fluoro-3-acetoxyestra-3,5-dien-17-one.
2 . A process for preparing 11β-fluoro-3-acetoxyestra-3,5-dien-17-one, characterized in that 11α-hydroxyestra-4-ene-3,17-dione is allowed to react with 1 to 3 equivalents of n-nonafluorobutanesulfonyl fluoride and 3 to 5 equivalents of diazabicycloundecene (DBU) at −40 to −20° C. in an organic aprotic solvent and, after an aqueous intermediate workup, reacted with 5 to 10 equivalents of acetylating agent in the presence of 0.01 to 1 equivalent of a strong acid, and the precipitated product is obtained by filtering the reaction mixture.
3 . The process for preparing 11β-fluoro-3-acetoxyestra-3,5-dien-17-one as claimed in claim 2 , characterized in that more than 3 equivalents of DBU are used.
4 . The process for preparing 11β-fluoro-3-acetoxyestra-3,5-dien-17-one as claimed in claim 2 , characterized in that ethyl acetate is used as the solvent.
5 . The process for preparing 11β-fluoro-3-acetoxyestra-3,5-dien-17-one as claimed in claim 2 , characterized in that reaction is effected with acetic anhydride as the acetylating agent.
6 . The process for preparing 11β-fluoro-3-acetoxyestra-3,5-dien-17-one as claimed in claim 2 , characterized in that reaction is effected with p-tolulenesulfonic acid (p-TsOH) as the strong acid.