| 摘要 |
17b - Hydroxy - 4,9(11) - androstadien - 3-one is obtained in a process which comprises cleaving the 17-side chain using acidic lead tetracetate or periodic acid, from 11b ,17a ,20,21-tetrahydroxy - 4 - pregnen - 3 - one 21 - acetate (or the 11a -hydroxy epimer), to form the corresponding 17-ketone, reacting the latter with N-bromoacetamide and sulphur dioxide to produce the corresponding 9(11)-dehydro product, protecting the 3-keto group by means of a 3-enamine, 3-ketal or 3-enol lower alkyl ether, and reducing the 17-ketone group, followed by the removal of the 3-ketone protecting group. |
