The stereochemistry of hydride reduction of erythrinan-7, 8-diones was markedly affected by the bulkiness of the reagent and the polarity of the solvent : sodium borohydride in ethanol-tetrahydrofuran gave the 7β-hydroxy isomers and tetrabutylammounium borohydride in methanol gave the 7α-hydroxy isomers, stereoselectively. This can be explained in terms of fluctuation of the balance between product development control and approach control. The structures of the products were established by chemical and spectroscopic means. Their O-mesylates were hydrolyzed under basic conditions with epimerization to give a mixture of alcohols with a preference for the 7β-hydroxy derivatives. A similar epimerization of the mesyloxy group was also observed in lithium aluminum hydride reduction.
硼氢化钠在
乙醇-
四氢呋喃中可生成 7β-羟基异构体,而四丁基
铵硼氢化钠在
甲醇中可生成 7α- 羟基异构体。这可以用产品开发控制和方法控制之间的平衡波动来解释。通过
化学和光谱手段确定了产品的结构。它们的 O-
甲磺酸盐在碱性条件下
水解并发生外嵌合反应,生成一种
醇类混合物,其中 7β- 羟基衍
生物更受青睐。在
氢化铝锂还原过程中,也观察到了类似的间羟基表聚现象。