The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States.
J Org Chem. 2018 Jun 1;83(11):6066-6085. doi: 10.1021/acs.joc.8b00728. Epub 2018 May 18.
(+)-Psiguadial B is a diformyl phloroglucinol meroterpenoid that exhibits antiproliferative activity against the HepG2 human hepatoma cancer cell line. This full account details the evolution of a strategy that culminated in the first enantioselective total synthesis of (+)-psiguadial B. A key feature of the synthesis is the construction of the trans-cyclobutane motif by a Wolff rearrangement with in situ catalytic, asymmetric trapping of the ketene. An investigation of the substrate scope of this method to prepare enantioenriched 8-aminoquinolinamides is disclosed. Three routes toward (+)-psiguadial B were evaluated that featured the following key steps: (1) an ortho-quinone methide hetero-Diels-Alder cycloaddition to prepare the chroman framework, (2) a Prins cyclization to form the bridging bicyclo[4.3.1]decane system, and (3) a modified Norrish-Yang cyclization to generate the chroman. Ultimately, the successful strategy employed a ring-closing metathesis to form the seven-membered ring and an intramolecular O-arylation reaction to complete the polycyclic framework of the natural product.
(+)-Psiguadial B 是一种二糠基间苯三酚倍半萜类化合物,对 HepG2 人肝癌癌细胞系具有抗增殖活性。本完整说明详细介绍了一种策略的演变,该策略最终实现了(+)-psiguadial B 的首次对映选择性全合成。合成的一个关键特征是通过沃尔夫重排构建反式环丁烷基序,同时原位催化、不对称捕获烯酮。公开了对该方法制备对映体富集的 8-氨基喹啉酰胺的底物范围的研究。评估了三种合成(+)-psiguadial B 的路线,其关键步骤如下:(1)邻醌甲醚杂 Diels-Alder 环加成制备色满骨架,(2)Prins 环化形成桥联双环[4.3.1]癸烷系统,(3)改进的 Norrish-Yang 环化生成色满。最终,成功的策略采用闭环复分解反应形成七元环,以及分子内 O-芳基化反应完成天然产物的多环骨架。