Reactivity ofβ-Carbolines and Cyclopenta[b]indolones Prepared from the Intramolecular Cyclization of 5(4H)-Oxazolones Derived fromL-Tryptophan
作者:Glenn C. Condie、Jan Bergman
DOI:10.1002/ejoc.200300673
日期:2004.3
omethyl-1,3-oxazol-5(4H)-one (4) was shown to undergo an intramolecular reaction in the presence of TFA, to afford a β-carboline 5 and a cyclopenta[b]indolone 6 by nucleophilic addition at C-2 and C-5, respectively. The distribution of these two products was found to be dependent on the reaction temperature, with lower temperatures favouring the formation of the β-carboline 5. Subsequent reactions
4-(1H-Indol-3-ylmethyl)-2-trichloromethyl-1,3-oxazol-5(4H)-one (4) 显示在 TFA 存在下进行分子内反应,得到 β-咔啉5 和环戊二烯 [b] 吲哚酮 6 分别在 C-2 和 C-5 处亲核加成。发现这两种产物的分布取决于反应温度,较低的温度有利于 β-咔啉 5 的形成。随后对 β-咔啉 5 进行的反应导致形成 canthine 和 canthin-6-one衍生品。这些合成均涉及 1-甲酰基-β-咔啉-3-羧酸甲酯 (20),这是一种有用的前体,通过四步程序从容易获得的 L-色氨酸中以 54% 的产率制备。环戊二烯 [b] 吲哚酮 6 很容易进行氧化脱酰胺,得到环戊二烯 [b] 吲哚-2,3-二酮 (37),