Paquette Leo A, Dong Shuzhi, Parker Gregory D
Evans Chemical Laboratories, The Ohio State University, Columbus, OH 43210, USA.
J Org Chem. 2007 Sep 14;72(19):7135-47. doi: 10.1021/jo070862j. Epub 2007 Aug 15.
A program directed toward an asymmetric synthesis of pestalotiopsin A is described. The routing begins with the dextrorotatory cyclobutanol 37, which is combined with the enantiomerically defined building blocks ent-15 and 16. These units are incorporated via stereocontrolled 1,2-nucleophilic addition and anti-aldol coupling, respectively. With these straightforward reactions accomplished, the sequel involved the introduction of terminal double bonds in anticipation of the fact that the (E)-cyclononene substructure could be realized by ring-closing metathesis. This central issue was evaluated with several diene substrates and catalysts, all to no avail. Cross-metathesis experiments involving 59 and 65 with the functionalized heptene 60 revealed a marked difference in the inability to engage interaction with the ruthenium catalyst. This awkwardness could not be skirted.
描述了一个针对 Pestalotiopsin A 不对称合成的方案。该路线从右旋环丁醇 37 开始，它与对映体定义的结构单元 ent-15 和 16 相结合。这些单元分别通过立体控制的 1,2-亲核加成和反羟醛缩合反应引入。完成这些直接反应后，后续步骤涉及引入末端双键，因为预期 (E)-环壬烯亚结构可通过闭环复分解反应实现。用几种二烯底物和催化剂对这个核心问题进行了评估，但均未成功。涉及 59 和 65 与官能化庚烯 60 的交叉复分解实验表明，它们与钌催化剂无法发生相互作用，存在显著差异。这种棘手情况无法回避。
