Synthesis of 5-Acetyloxazoles and 1,2-Diketones from β-Alkoxy-β-ketoenamides and Their Subsequent Transformations
作者:Tilman Lechel、Markus Gerhard、Daniel Trawny、Boris Brusilowskij、Luise Schefzig、Reinhold Zimmer、Jürgen P. Rabe、Dieter Lentz、Christoph A. Schalley、Hans-Ulrich Reissig
DOI:10.1002/chem.201100382
日期:2011.6.27
cyclized to 5‐acetyloxazole derivatives. The synthesis is very flexible with respect to the substitution pattern at C‐2 and C‐4 of the oxazole core. A mechanistic suggestion for the oxazole formation is presented on the basis of 18O‐labeled compounds and their mass spectrometric analysis. In several cases, 1,2‐diketones are formed as side products or even as major components. The acetyl moiety at C‐5 of the
锂化的烷氧基丙二烯,腈和羧酸已被用作三组分反应的前体,从而导致高度取代的β-烷氧基-β-酮烯酰胺。用三氟乙酸处理后,这些酰胺很容易环化成5-乙酰基恶唑衍生物。关于恶唑核心在C-2和C-4处的取代方式,合成非常灵活。在18的基础上提出了恶唑形成的机理建议。O标记的化合物及其质谱分析。在某些情况下,1,2-二酮是副产品甚至主要成分。恶唑衍生物C-5处的乙酰基可以有效地转化为烯基或炔基部分,从而可以进行大量后续反应。乙酰基的缩合反应提供了预期的肟或。通过进行Fischer反应,苯hydr可以转移到吲哚中,这突出了5-乙酰基恶唑在制备高度取代的(多)杂环体系中的潜力。C-2处的炔基易于加成反应,从而提供具有有趣光物理性质的烯胺。Sonogashira偶联是使用5-炔基取代的恶唑完成的,提供了预期的芳基取代的产物。该炔基单元用于制备新的星形三恶唑衍生物。通过扫描隧道显微镜(STM)证明了这种多价化合