6.alpha.,9.alpha.-difluoro-11.beta.,17.alpha.-dihydroxy-16.alpha.-methyl-4- pregnene-3,20-dione and its derivatives of general formula I ##STR1## wherein symbolizes a single bond or a double bond, and X is H, Br, I or alkanoyloxy with 1-8 carbon atoms, are prepared by a novel process from 3.beta.,17.alpha.-dihydroxy-16.alpha.-methyl-5-pregnen-20-one. The resultant pregnene derivatives are useful as intermediates in the production of flumethasone.
                            6.alpha.,9.alpha.-二
氟-11.beta.,17.alpha.-二羟基-16.alpha.-甲基-4-孕烯-3,20-二酮及其一般式I的衍
生物##STR1##其中符号化为单键或双键,X为H,Br,I或1-8个碳原子的烷酰氧基,通过一种新的方法从3.beta.,17.alpha.-二羟基-16.alpha.-甲基-5-孕烯-20-酮制备而成。所得的孕烯衍
生物可用作
氟美松的中间体。