The final phase of the total synthesis of (−)-spirochensilide A is described. A tungsten-mediated cyclopropene-based Pauson–Khand reaction was developed to form the spiral CD ring system with desired stereochemistry at the C13 quaternary center. Other important steps enabling completion of this synthesis included an intermolecular aldol condensation to link the ABCD core with the EF fragment and a Cu-mediated 1,4-addition to stereoselectively install the C21 stereogenic center. The chemistry developed for this total synthesis of (−)-spirochensilide A (1) will aid the synthesis of polycyclic natural products bearing this unique spiral ring system.

中文翻译：

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（-）-螺碳硅化物A的不对称全合成，第2部分：最终阶段和完成

描述了（-）-螺碳硅化物A的全合成的最终阶段。钨介导的基于环丙烯的Pauson-Khand反应得以发展，以形成具有所需立体化学的螺旋CD环系统，并在C13四元中心处形成。使该合成完成的其他重要步骤包括分子间羟醛缩合以将ABCD核心与EF片段连接，以及Cu介导的1,4-加成以立体选择性地安装C21立体中心。为（-）-螺碳硅化物A（1）的这种全合成而开发的化学方法将有助于带有这种独特螺旋环系统的多环天然产物的合成。