Here we report the first example of the dimerisation of azirines to 2H-imidazoles or 3,5-disubstituted pyridazines from a reaction promoted by FeCl2. An azirine complex with a radical structure is proposed as an intermediate. Cyclopropyl ketones and pyrrolines are isolated when the reaction is carried out in the presence of styrenes.
A facile synthesis of 1H-imidazoles by direct oxidative annulation of aryl methylketones and primary amines has been developed in the presence of TEMPO under weakly acidic conditions. By replacing amines with ammonium acetate, 2H-imidazole skeletons were achieved for the first time from ketones. Substrates containing various functional groups, such as alkyl, aryl, naphthyl, halogen (F, Cl, Br, I)
在弱酸性条件下,在 TEMPO 存在下,通过芳基甲基酮和伯胺的直接氧化环化,开发了一种简便的 1 H-咪唑合成方法。通过用乙酸铵代替胺类,首次从酮类中获得了2 H-咪唑骨架。含有各种官能团的底物,如烷基、芳基、萘基、卤素(F、Cl、Br、I)、硝基、三氟甲基、磺酰基酯、呋喃基、噻吩基和吡啶基,很容易转化为所需的产物。通过咪唑的放大合成和 Sonogashira 偶联功能化验证了该方法的应用潜力。从机理上讲,α-TEMPO-烯胺加合物可以作为关键的反应中间体。
Synthesis of 2H-imidazoles via copper-catalyzed homo/cross-coupling of oxime acetates
作者:Min Liu、Bifu Liu、Hongyan Chen、Qian Wang、Lixin Liu、Kejun Feng、Zijia Wang、Qiang Li
DOI:10.1039/d4ob00977k
日期:——
applying an oximeacetate block as the sole component via oxidative homo/cross-coupling catalyzed by Cu(I) was developed. This strategy provides a straightforward method to produce a series of substituted 2H-imidazoles in moderate to excellent yields. The transformation process is straightforward to operate and is considered as a readily available catalytic system exhibiting good substrate compatibility