of fluocinolone acetonide with combination of bio-fermentation was developed from 21-acetyloxy-17α-hydroxy-4,9(11)-diene-3,20-dione (1a). Process of the 6α and 9α fluorination steps was studied, and it was observed that the stereoselectivity of 6α fluorination is highly substrate dependent. After an extensive screening on the fluorinating reagents and activation reagents, 6α-F was introduced in 85%
There is provided a process for preparing 21-acetyloxy-6-alpha-fluoro-pregna-1,4,9(11),16-tetraene-3,20-dione compound of Formula I, which comprises reacting 21-acetyloxy-pregna-1,3,5,9(11),16-pentaene-3-oxo acetate with a fluorinating agent.
[EN] CONVERSION OF DELTA<16>-STEROID TO A DELTA<17(20)>-20-SILYL ETHER
申请人:THE UPJOHN COMPANY
公开号:WO1990015068A1
公开(公告)日:1990-12-13
(EN) The present invention is a process for conversion of $g(D)16-steroids (I), to the corresponding $g(D)17(20)-20-silyl ether (III), by reaction with (1) a preformed copper hydride or a metal hydride reducing agent in the presence of a copper species and (2) a silylating agent. The $g(D)17(20)-20-silyl ethers (III) are useful intermediates in the preparation of steroids useful as pharmaceuticals.(FR) L'invention concerne un procédé pour transformer des stéroïdes-$g(D)16 (I) en un éther $g(D)17(20)-20-silyle (III) correspondant par la réaction avec (1) un hydride de cuivre préformé ou avec un agent de réduction d'hydride métallique en présence d'une espèce de cuivre et (2) un agent de silylation. Les éthers $g(D)17(20)-20-silyle (III) sont des intermédiaires utiles dans la préparation de stéroïdes utilisables en tant que produits pharmaceutiques.