红霉素肟贝克曼重排反应中的构型异构化

The Configurational Isomerization of Erythromycin Oxime During Beckmann Rearrangement

碱性条件下红霉素肟容易由E构型转化为Z构型从而达到平衡。但发现同样是在碱性条件下的贝克曼重排反应后,E构型产物的质量分数相对于原料中E肟的质量分数而言提高了,而Z构型产物的质量分数相应降低了,说明在贝克曼重排反应过程中Z构型异构化为了E构型。该异构化现象的发现为控制阿奇霉素生产条件,从而降低产物中由红霉素Z肟重排得到的副产物的质量分数,提高最终产品阿奇霉素的产率提供了参考,对异构化机理也进行了探讨。

The E configuration of erythromycin oxime was found to transfer easily to the Z configuration to equilibrium under the condition of alkalescence. But it was found that under the same condition during Beckmann rearrangement,relative to the content of E oxime in starting material,the content of the product of E configuration increased,while the content of the product of Z configuration reduced. It means that the Z configuration isomerizes to E configuration during Beckmann rearrangement. This discovery is helpful for controlling the condition during the synthesis of azithromycin to reduce the content Of the by-product from Z oxime and to improve the yield of azithromycin. The mechanism of configurational isomerization was also discussed.