Graduate School of Pharmaceutical Sciences , Tohoku University , 6-3 Aza-aoba, Aramaki , Aoba-ku , Sendai 980-8578 , Japan.
J Org Chem. 2018 Aug 17;83(16):9430-9441. doi: 10.1021/acs.joc.8b01075. Epub 2018 Jul 2.
Spiromamakone A is a racemic natural product having a naphthyl acetal group on a spiro[4,4]nonadiene skeleton. Its total synthesis was achieved by double oxa-Michael addition of 1,8-dihydroxynaphthalene to 2-(1-bromoalkylidene)-4-isopropoxy-4-cyclopentene-1,3-dione, which was prepared by palladium(II)-catalyzed ring expansion of 4-(1-alkynyl)-4-hydroxy-3-isopropoxy-2-cyclobuten-1-one, and a subsequent intramolecular aldol reaction. The synthesis using optically active intermediates enabled identification of the racemization step of spiromamakone A and revealed that spiromamakone A and spiropreussione A are identical; the latter had been reported as a constitutional isomer of the other.
螺旋马酮 A 是一种外消旋天然产物，其螺[4,4]壬烷骨架上带有萘基缩醛基团。它的全合成是通过 1,8-二羟基萘与 2-（1-卤代亚烷基）-4-异丙氧基-4-环戊烯-1,3-二酮的双氧亚甲基迈克尔加成来实现的，后者是通过钯（II）催化的 4-（1-炔基）-4-羟基-3-异丙氧基-2-环丁烯-1,3-二酮的环扩张制备的，以及随后的分子内羟醛缩合反应。使用光学活性中间体的合成能够确定螺旋马酮 A 的外消旋化步骤，并表明螺旋马酮 A 和螺旋普雷乌辛酮 A 是相同的；后者曾被报道为另一种的构象异构体。
