polyhydroxylated 18-membered lichen macrolide (+)-aspicilin was synthesized in 12 steps and 17% yield (longest linear sequence) starting from d-mannose and (S)-propylene oxide as the source of the stereogenic centers. Key steps were a palladium-catalyzed Csp3X–Csp3ZnX Negishi cross-coupling affording an ω-hydroxy hemiacetal which was macrocyclized via a domino addition–Wittig olefination reaction with the
以d-
甘露糖和(S)-环氧
丙烷为立体异构中心的来源,以12个步骤合成了多羟基化的18元地衣大环内酯(+)-aspicilin,产率为17%(最长线性序列)。关键步骤是
钯催化的C sp3 X–C sp3 ZnX Negishi交叉偶联,得到ω-羟基
半缩醛,该羟基
缩醛通过多米诺加成反应–维蒂希烯化反应与累积的叶立德Ph 3
PCCO进行了大环化。这种合成方法还允许将Aspicilin的6-OH与d-去糖胺进行区域选择性糖基化反应,从而快速进入具有潜在抗生素活性的嵌合
大环内酯类药物。