The first total synthesis of (−)-dendroside C aglycon, consisting of a 1,4,5-tri-cis-guaiane skeleton, from a versatile hydroazulene intermediate has been accomplished. The key features of the syntheses include the stereoselective preparation of the unusual cis-hydroazulene core via a sequence of a unique Dieckmann condensation of the bicyclic lactone system, which was concisely prepared by the tandem conjugate addition and intramolecular allylic alkylation of a butenolide precursor, and construction of the characteristic tricyclic skeleton by a carbene-mediated cyclopropanation.

中文翻译：

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1,4,5-三顺式-愈创木酚倍半萜的立体选择性合成：（-）-树胶苷C糖苷配基的首次全合成

已完成了从一种多功能的水az烯中间体首次合成由（1,4,5-三顺式-guaiane骨架）组成的（-）-树胶苷C糖苷配基。合成的关键特征包括通过双环内酯系统独特的Dieckmann缩合的序列立体选择性地制备不寻常的顺式-氢氮杂烯核，该序列是通过串联共轭加成和丁烯内酯前体的分子内烯丙基烷基化而简明地制备的，以及卡宾介导的环丙烷化反应制备具有特征性的三环骨架。