In this report, we documented novel strategy for the synthesis of bioactive polysubstituted 2-amino-4H-chromine derivatives under a heterogeneous Al-MCM-41-LDH@APTES (ALAM) catalysis. A synthetic procedure is developed to prepare Al-MCM-41-LDH@APTES (ALAM) heterogeneous basic catalysts. Mesoporous Al-MCM-41 is functionalized by known grafting chemistry via layered double hydroxide (LDH) nanosheets and (3-aminopropyl)triethoxysilane (APTES) moiety as a basic organocatalyst. The resulting catalysts contain amino group functionality on the external surface as well as inside the layers and the basicity can be tuned by the loading of APTES. The samples were fully characterized by 29Si and 13C CP/MAS NMR, infrared absorption spectroscopy, TEM, XPS, EDX, TGA, XRD, CO2-TPD, N2 adsorption isotherms measurements, and they were successfully examined for the cascade type Knoevenagel–Michael addition reactions. The product yields associated with these substrates were optimized, and key reaction parameters affecting the yields were identified. The present catalytic method is simple and robust for diversity oriented synthesis which proceeds good to excellent yields without generating any hazards waste. The broad substrate scope, excellent functional group compatibility makes this protocol highly useful towards synthesis of polysubstituted α-cyanoacrylates, α-cyanoacrylonitriles and 2-amino-4H-chromenes with an electron-donating or electron-withdrawing group. We have also successfully established a flow reaction system, gram-scale synthesis as well as catalyst recyclability up to six catalytic cycles without appreciable loss of its activity.

中文翻译：

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有机催化级联 Knoevenagel-Michael 加成反应：多取代 2-氨基-4H-色烯衍生物的直接合成

在本报告中，我们记录了在异质 Al-MCM-41-LDH@APTES (ALAM) 催化下合成生物活性多取代 2-氨基-4H-色胺衍生物的新策略。开发了一种合成程序来制备 Al-MCM-41-LDH@APTES (ALAM) 多相碱性催化剂。介孔 Al-MCM-41 通过已知的接枝化学通过层状双氢氧化物 (LDH) 纳米片和 (3-氨基丙基) 三乙氧基硅烷 (APTES) 部分作为碱性有机催化剂进行功能化。所得催化剂的外表面和层内都含有氨基官能团，并且可以通过加载 APTES 来调节碱度。通过 29Si 和 13C CP/MAS NMR、红外吸收光谱、TEM、XPS、EDX、TGA、XRD、CO2-TPD、N2 吸附等温线测量对样品进行了全面表征，并且他们成功地检测了级联型 Knoevenagel-Michael 加成反应。优化了与这些底物相关的产物产量，并确定了影响产量的关键反应参数。本催化方法对于面向多样性的合成而言简单且稳健，其在不产生任何危险废物的情况下进行良好至优异的产率。广泛的底物范围、优异的官能团兼容性使该协议对于合成多取代的 α-氰基丙烯酸酯、α-氰基丙烯腈和具有给电子或吸电子基团的 2-氨基-4H-色烯非常有用。我们还成功地建立了流动反应系统、克级合成以及催化剂可回收性高达六个催化循环，而其活性没有明显损失。