合成路线图解说明: The reaction of cyanohydrineketal (I) with dimethyl(chloromethyl)silyl chloride (A), TEA and DMAP in THF gives the silylated cyanohydrine (II), which is treated with Li and 4,4'-di-tert-butylbiphenyl (DBB) in THF followed by acidification with HCl yields 17alpha-hydroxy-19-norpregna-4,9-diene-3,20-dione (III). The reaction of (III) with ethylene-glycol and TsOH afford the bis ethylenedioxy derivative (IV), which is epoxidized with H2O2 and trifluoroacetone in dichloromethane affording the monoepoxide (V). The Grignard condensation of (V) with 4-(dimethylamino)phenylmagnesium bromide in THF provides the 11-beta-(dimethylamino) derivative (VII), which is dehydrated and deprotected with sulfuric acid in refluxing ethanol to furnish 11-beta-[4-(dimethylamino)phenyl]-17alpha-hydroxy-19-norpregna-4,9-diene-3,20-dione (VIII). Finally, this compound is acetylated with AcOH and trifluoroacetic anhydride in dichloromethane. |