| 摘要 |
1457665 Preparation of 21-fluorosteroids CIBA-GEIGY AG 26 Feb 1974 [28 Feb 1973] 8620/74 Heading C2U 21-Fluoro-steroids are prepared by treating steroids of the partial formula (wherein X is a reactively esterified hydroxyl group other than a fluorine atom; Y is H or a C 1-7 aliphatic radical; Z is an optionally substituted geminal hydrocarbon radical in which the C atom attached to the 16- and 17-oxygen atoms does not carry a double bond; and "st" is the remainder of the steroid) successively (a) with the product of the action of an alkali metal on a polycyclic aromatic hydrocarbon in an aprotic solvent, and (b) with perchloryl fluoride in an aprotic solvent. The preferred metal-hydrocarbon reagent is lithium biphenyl. The postulated intermediate (not isolated) contains a 17#-C( = CH 2 )OM group wherein M is the alkali metal. In the sole example, the product is 3,3 - ethylenedioxy - 16α,17α- isopropylidenedioxy - 20 - oxo - 21 - fluoro - 5 - pregnene.
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