Lambson Katharine E, Dacko Christopher A, McNeill Jeffrey M, Akhmedov Novruz G, Söderberg Björn C G
C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA.
Tetrahedron. 2019 Dec 6;75(49). doi: 10.1016/j.tet.2019.130714. Epub 2019 Oct 21.
Dilemmaones A-C are naturally occurring tricyclic indole alkaloids possessing a unique hydroxymethylene or methoxymethylene substituent at the C2 position of the indole core and a C6-C7 fused cyclopentanone. Dilemmaone B has been prepared in 5 steps from 5-methylindan-1-one, and dilemmaone A has been prepared in 3 steps from a common precursor, 6-bromo-5-methyl-7-nitroindan-1-one. In both syntheses, key steps include a Kosugi-Migita-Stille cross coupling and a reductive cyclization using hydrogen gas and a transition metal catalyst.
困境化合物A - C是天然存在的三环吲哚生物碱,在吲哚核心的C2位置具有独特的羟基亚甲基或甲氧基取代基以及C6 - C7稠合环戊酮。困境化合物B由5 - 甲基茚满 - 1 - 酮经5步反应制备而成,困境化合物A由共同前体6 - 溴 - 5 - 甲基 - 7 - 硝基茚满 - 1 - 酮经3步反应制备而成。在这两种合成方法中,关键步骤包括小杉 - Migita - 施蒂勒交叉偶联反应以及使用氢气和过渡金属催化剂的还原环化反应。