The NHC-catalyzed reactions of ortho electron-deficient vinyl substituted arylaldehydes with nitrosoarenes were studied. The reactions produced multifunctional 2,3-benzoxazin-4-ones in good to excellent yields via a cascade aza-benzoin reaction between aldehyde and nitroso groups followed by an intramolecular oxo-Michael addition. The resulting 1-acetate substituted 2,3-benzoxazinones were transformed into a new type of β-hydroxycarboxylate derivatives or 3-oxo-1-isobenzofuranacetates, respectively, under different reductive conditions. This work not only provides a simple and efficient method for the construction of multifunctional 2,3-benzoxazin-4-ones of potential pharmacological interest, but also expands the application of NHC-catalyzed cascade reactions in the formation of carbon–heteroatom and heteroatom–heteroatom bonds.
研究了 NHC 催化的正交缺电子
乙烯基取代芳基醛与亚硝基烯烃的反应。这些反应通过醛和亚硝基之间的级联偶氮-苯偶氮反应以及分子内氧化-迈克尔加成反应,生成了多功能的 2,3-苯并恶嗪-4-酮,收率从良好到极佳。在不同的还原条件下,生成的 1-乙酸酯取代的 2,3-苯并恶嗪酮分别转化为新型的 β-羟基
羧酸酯衍
生物或 3-氧代-1-
异苯并呋喃乙酸酯。这项工作不仅为构建具有潜在药理作用的多功能 2,3-苯并恶嗪-4-酮提供了一种简单高效的方法,而且拓展了 NHC 催化级联反应在碳-杂原子键和杂原子-杂原子键形成中的应用。