N-吡啶-2-基烯胺酮与马来酰亚胺 2+2+2环加成反应合成吡咯并3,4-e异吲哚-1,3,6,8-四酮类化合物

Multicomponent synthesis of pyrrolo3,4-eiso-indole-1,3,6,8-tetraones by 2+2+2 cycloaddition of N-pyridin-2-ylenaminones with maleimides

  • 摘要: 建立了以N-吡啶-2-基烯胺酮类化合物1和马来酰亚胺衍生物2为原料,以乙酸铜做催化剂,吡啶-2-基为导向基团,通过三组分2+2+2环化合成了具有分子多样性的吡咯并3,4-e异吲哚-1,3,6,8-四酮 (pyrrolo3,4-eisoindole-1,3,6,8-tetraones (PIITOs)) 3. 该方法有效地利用底物N-吡啶-2-基烯胺酮的N-吡啶-2-基为无痕导向基,原位参与并有效活化N-吡啶-2-基烯胺酮的α-C的反应活性,在反应完成后它会自动脱离导向基团,成功实现了功能化PIITO的三组分2+2+2环加成合成. 所合成的产物都经1H NMR、13C NMR和HRMS表征,其中,化合物3a获得单晶结构. 该方法操作简单,路线简洁,底物简单易得,目标产物结构多样,为筛选具有潜在生物活性的PIITOs提供了新的合成方法.

     

    Abstract: In this paper, we developed a three-component protocol for the synthesis of diverse pyrrolo3,4-eisoindole-1,3,6,8-tetraones (PIITOs) 3 using N-pyridin-2-yl enaminones 1 and maleimide derivative 2 as substrates, catalyzed by copper(Ⅱ) acetate with pyridin-2-yl as a directing group. These strategies can be used to synthesize functionalized PIITOs for combinatorial and parallel syntheses via one-pot reactions. This approach effectively utilizes the N-pyridin-2-yl of enaminones as a traceless directing group that participates in the reaction in situ. It automatically disengages from the directing group after the reaction is completed, fully activating the reactivity of the α-C of enaminones. This method successfully achieves the three-component 2+2+2 cycloaddition synthesis of functionalized PIITOs. The synthesized products were characterized by 1H NMR, 13C NMR and HRMS. Additionally, the structure of target compound 3a was confirmed by X-ray crystallography. The method has simple operation, simple route, simple substrate and wide range, so it can synthesize a variety of products, and provides a new method for screening PIITOs with potential biological activities.

     

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