| 摘要 |
Disclosed is an improved process for the synthesis of 6-bromo-17,21-dihydroxy-3,11,20-trioxo-1,4,-pregnadienes 17,21-diesters. In particular, this invention relates to the conversion of 17,21-dihydroxy-3,11,20-trioxo-1,4-pregnadienes 17,21-diesters to 6-borom-17,21-dihyroxy-3,11,20-trioxo-1,4-pregnadienes-17-21-diesters via bromination under ionic conditions, e.g. bromine in acetic acid.
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