The carbon skeleton of the Stemona alkaloids stemokerrin and cochinchistemonine was assembled from three building blocks (a piperidine, a furan, and a tetronate). Key steps linking the fragments included a Stille cross-coupling (piperidine/furan) and an aldol-type addition of a tetronate. The furan served as a latent 1,4-difunctional compound which was converted into a γ-ketolactone by a type II photooxygenation
Stemona
生物碱stemokerrin 和cochinchistemonine的
碳骨架由三个组成部分(
哌啶、
呋喃和tetronate)组装而成。连接片段的关键步骤包括 Stille 交叉偶联(
哌啶/
呋喃)和醛醇型添加 tetronate。
呋喃作为一种潜在的 1,4-双官能化合物,通过 II 型光
氧化作用转化为 γ-
酮内
酯。试图通过后期
氧化或消除来构建茎干蛋白的 C12-C13 双键仍然不成功。取而代之的是非
天然产物dihydrostemokerrin和furostemokerrin。