Two syntheses of the C15 ginkgolide, bilobalide, are presented. One approach results in a formal synthesis by intersecting an intermediate in the Corey synthesis, while a second approach results in a completed total synthesis which is considerably shorter than the first. Both approaches rely on a stereoselective intramolecular [2+2] photocycloaddition to control much of the stereochemistry. A diastereoselective
介绍了 C15
银杏内酯、bilobalide 的两种合成方法。一种方法通过在 Corey 合成中与中间体相交而导致正式合成,而第二种方法导致完整的全合成,它比第一种方法短得多。这两种方法都依赖于立体选择性分子内 [2+2] 光环加成来控制大部分立体
化学。非对映选择性羟醛缩合用于在第二种方法中建立仲醇和叔醇之间的相对立体
化学关系。这避免了在先前的方法中遇到的引入叔
甲醇的问题。