Total Synthesis of (−)-Spirotryprostatin B: Synthesis and Related Studies

The total synthesis of spirotryprostatin B, a cytostatic spiro[pyrrolidine-3,3‘-oxindole] alkaloid, is
described. The key step of the synthetic approach consists of the application of the MgI2-mediated ring-expansion reaction of a spiro[cyclopropane-1,3‘-oxindole] with an aldimine, leading to rapid assembly of
the spirotryprostatin core. The route documents the installation of the prenyl side chain by Julia−Kocieński
olefination of a key aldehyde precursor, a transformation that ultimately allows for facile synthesis of
analogues and facilitates structure−activity relationships studies

本文报道了具有细胞生长抑制活性的螺[吡咯烷-3,3'-吲哚酮]类生物碱螺环脯氨酰肽B（spirotryprostatin B）的全合成方法。该合成策略的关键步骤为：利用碘化镁（MgI₂）介导的螺[环丙烷-1,3'-吲哚酮]与亚胺（aldimine）的扩环反应，快速组装得到螺环脯氨酰肽B的核心骨架。本路线通过对关键醛前体实施Julia-Kocieński烯化反应，完成了异戊烯基侧链的引入；该转化手段不仅可便捷合成系列类似物，亦为构效关系（structure-activity relationships）研究提供了便利。