Synthetic studies on terpene compounds. Part 13. Total synthesis of fraxinellone
作者:Takashi Tokoroyama、Yoshiyasu Fukuyama、Takashi Kubota、Kenji Yokotani
DOI:10.1039/p19810001557
日期:——
The total synthesis of fraxinellone (1), the simplest example of a degraded limonoid, via the 6-formyl-2,6-dimethyl-cyclohex-2-enecarboxylates (2) is described. In the initial approach the C-6 methylation of ethyl 6-formyl-2-methylcyclohex-2-enecarboxylate (7) was carried out by cyclopropanation and ring cleavage which unexpectedly gave the bicyclo[2.2.1]heptene compound (20), with a poor yield of
描述了通过6-甲酰基-2,6-二甲基-环己-2-烯基羧酸酯(2)进行的全合成的fraxinellone(1)(降解的柠檬苦素的最简单实例)。在最初的方法中,通过环丙烷化和环裂解来进行6-甲酰基-2-甲基环己-2-烯基羧酸乙酯(7)的C-6甲基化反应,出乎意料地得到了双环[2.2.1]庚烯化合物(20),所需产品收率不佳。随后,通过3-甲基戊-2,4-二烯酸乙酯与甲基丙烯醛之间的Diels-Alder反应有效地合成了关键中间体(2)。醛酯(2)与呋喃基锂反应,然后与碱进行双键异构化,得到(±)-六氢新萘酮,以及相应的非对映异构体。