sensitive groups (hydroxyl, cyano, amino, vinyl, ethynyl, ester, and even acetyl groups) and heterocycles, which affords functionalized benzoxazoles in good to excellent yields by employing low catalyst loading (2 mol % Cu). The characterization and plausible catalytic mechanism of Cu(OH)x/OMS-2 are described. The notable features of our catalytic protocol such as the use of air as the benign oxidant
Divers benzoxazole heterocyclic products have been synthesized by a facile, efficient, and eco‐friendly strategy. The synthesis of benzoxazoles was catalyzed by nanostructured iron(III)‐porphyrin complex at room temperature under green conditions.
One-Pot Multicomponent Reaction of Catechols, Ammonium Acetate, and Aldehydes for the Synthesis of Benzoxazole Derivatives Using the Fe(III)–Salen Complex
作者:Hashem Sharghi、Jasem Aboonajmi、Mahdi Aberi
DOI:10.1021/acs.joc.0c00560
日期:2020.5.15
The Fe(III)-salen complex has been applied successfully as a catalyst for the novel, simple, efficient, and one-pot multicomponent synthesis of benzoxazole derivatives from catechols, ammonium acetate as the nitrogen source, and aldehydes (nontoxic and cheap alternatives of amines) for the first time. Using this procedure, a wide range of benzoxazoles was successfully synthesized in the presence of
copper‐catalyzed aerobicoxidativeC(aryl)OHbondfunctionalization of catechols is reported. Under air, at room temperature, in the presence of a copper catalyst, catechols react with amines to produce the corresponding benzoxazoles in high yields. Mechanistic studies suggest that the reaction proceeds via an intriguing competitive oxidation and a synergetic catalysis between catechol and amine.
efforts toward their synthesis; however, the developed methods rely on prefunctionalized substrates and lack generality. Under metal-free conditions, a highly generalsynthesis of benzoxazoles direct from abundant and easily available phenols and amines is developed via a modular phenol functionalization controlled by TEMPO. In the reaction, various phenols and primary amines with a broad range of
苯并恶唑在天然产物、药物和功能材料中的普遍存在激发了许多对其合成的努力。然而,所开发的方法依赖于预功能化的底物,缺乏通用性。在无金属条件下,通过由 TEMPO 控制的模块化苯酚官能化,直接从丰富且容易获得的苯酚和胺中合成苯并恶唑。在该反应中,具有广泛官能团的各种苯酚和伯胺是相容的,产生结构和功能多样的苯并恶唑(64 个例子),而没有或微量观察到苯酚与胺转化的副产物。实际合成,尤其是药物 tafamidis,在通用性、选择性、效率、即使在低产量的情况下,也比传统方法具有原子经济和分步经济。从机理上讲,TEMPO 的自由基加合物与邻-cyclohexa-2,4-dien-1-one 自由基而不是公认的 cyclohexa-3,5-diene-1,2-diones 可以作为中间体。