Abstract

Allobetulin was converted to 3β-acetoxy-21β-acetyl-20β,28-epoxy-18α,19β-ursane, followed by reduction of the acetyl fragment and acid-catalyzed dehydration product. The structure of the obtained triterpenoid containing a trans-ethylidene substituent on the E ring was determined using two-dimensional ¹H–¹H COSY, ¹H–¹H NOESY, ¹H–¹³C HSQC, ¹H–¹³C HMBC correlation techniques.

中文翻译：

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由异白素合成 E 环中带有亚乙基片段的三萜类化合物

摘要

Allobetulin 被转化为 3β-acetoxy-21β-acetyl-20β,28-epoxy-18α,19β-ursane，随后乙酰片段和酸催化脱水产物被还原。使用二维¹ H– ¹ H COSY、¹ H– ¹ H NOESY、¹ H– ¹³ C HSQC、¹ H– ¹³ C HMBC 相关性确定所获得的 E 环上含有反式亚乙基取代基的三萜的结构技术。