| 摘要 |
The present invention relates to a novel process for the manufacture of (22 R,S)-16 alpha , 17 alpha -butylidenedioxy-11 beta , 21-dihydroxypregna-1,4-diene-3,20 dione (I) by reacting 11 beta , 16 alpha , 17 alpha 21-tetrahydroxypregna-1,4-diene (II) with butanal, CH3-CH2-CH2-CHO, in acetonitrile in presence of p-toluenesulphonic acid as a catalyst. |
