Total Synthesis of Murrayanine Involving 4,5-Dimethyleneoxazolidin-2-ones and a Palladium(0)-Catalyzed Diaryl Insertion
作者:Pablo Bernal、Joaquín Tamariz
DOI:10.1002/hlca.200790148
日期:2007.8
A new total synthesis of the natural carbazole murrayanine (1) was developed by using the 4,5-dimethyleneoxazolidin-2-one 12 as starting material. The latter underwent a highly regioselective Diels–Alder cycloaddition with acrylaldehyde (=prop-2-enal; 13) to give adduct 14 (Scheme 3). Conversion of this adduct into diarylamine derivative 9 was carried out via hydrolysis and methylation (Scheme 4).
以4,5-二亚甲基恶唑烷丁-2-酮12为起始原料,开发了一种新的天然咔唑Murrayanine(1)的全合成方法。后者与丙烯醛(= prop-2-enal; 13)进行了高度区域选择性的Diels-Alder环加成反应,得到加合物14(方案3)。这种加合物转化成二芳基胺衍生物9进行经由水解和甲基化(方案4)。与我们之前的合成方法不同,在这种合成方法中,二芳基胺衍生物被Pd II转化为1-化学计量环化,该新方法包括通过更有效的Pd 0催化的分子内二芳基偶合偶联(已应用于9)改善了环化作用,从而以较高的总收率获得了天然咔唑1。