| 摘要 |
<p>A cpd. (II) is treated with a strong base to give a 14-oxo-E-homoeburane, nitrosated to give a 14-oxo-hydroxyimino E-homoebenane, treated with an aldehyde a ketone to give the 14, 15-di-oxo-E-homoeburane then treated with NaOMe to give a vincamine (I). The last stage may be divided into two steps (1) hydrolysis with an acid or base to give the corresp. free acid then (2) methylation to give the ester. The intermediates also form part of the invention.</p> |
