Total Synthesis of the Natural Carbazoles Murrayanine and Murrayafoline A, Based on the Regioselective Diels-Alder Addition of<i>exo</i>-2-Oxazolidinone Dienes
作者:Joaquín Tamariz、Adriana Benavides、Javier Peralta、Francisco Delgado
DOI:10.1055/s-2004-831213
日期:——
synthesis of the natural carbazoles Murrayanine (1) and Murrayafoline A (3) is described. The key step in the synthetic route involved the regioselective cycloaddition of the diene 4,5-dimethylene-3-phenyl-1,3-oxazolidin-2-one (4) to acrolein (6) catalyzed by Lewis acids at low temperature. Direct aromatization of the substituted cyclohexene moiety of adduct 7, and further hydrolysis of the 2-oxazolidinone
描述了天然咔唑 Murrayanine (1) 和 Murrayafoline A (3) 的新合成方法。合成路线中的关键步骤涉及在路易斯酸的低温催化下,二烯 4,5-二甲基-3-苯基-1,3-恶唑烷-2-酮 (4) 与丙烯醛 (6) 的区域选择性环加成反应。加合物 7 的取代环己烯部分的直接芳构化,以及 2-恶唑烷酮环的进一步水解,被证明是一种比制备相应芳基苯胺 14 和 18 的相反合成序列更有效的策略。钯促进的环化后者以高总产率提供了所需的咔唑1和3。