Patra Sushree Aradhana, Nandi Monojit, Maurya Mannar R, Sahu Gurunath, Mohapatra Deepika, Reuter Hans, Dinda Rupam
Department of Chemistry, National Institute of Technology, Rourkela 769008, India.
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India.
ACS Omega. 2024 Jul 10;9(29):31910-31924. doi: 10.1021/acsomega.4c03528. eCollection 2024 Jul 23.
In this report, four new Ni(II)-unsymmetrical salen complexes, [NiL], were prepared by refluxing Ni(Ac)·4HO with unsymmetrical salen ligands, HL. All of the synthesized ligands and complexes were characterized by various physicochemical methods. Also, the solid-state structures of [NiL], [NiL], and [NiL] were defined through single-crystal X-ray diffraction methods. The catalytic potential of [NiL] was investigated by economic and environmentally friendly one-pot-three-component reactions (using reagent: 1,3-dicarbonyls, malononitrile, benzaldehyde, or its derivatives) for the synthesis of biologically active 2-amino-3-cyano-4-pyran derivatives (total 16 derivatives). After optimization of the reaction conditions, this new synthetic protocol by taking Ni(II)-unsymmetrical salen complexes as catalysts shows excellent conversion with a maximum yield of up to 98% of the effective catalytic products within 1 h of reaction time. In addition, it was observed that the aromatic aldehyde containing an electron-withdrawing group as a ring substituent shows better conversion (up to 98%), and the electron-donating group substituent shows similar or less conversion compared to benzaldehyde under the optimized reaction conditions. From the comparison of results between all these Ni complexes, it was found that the efficiency of the catalytic performance follows the order [NiL] > [NiL] > [NiL] > [NiL]. A possible reaction pathway was predicted and established through UV-vis spectroscopy. Intermediate II proposed in the reaction pathway was also trapped and characterized through H and C NMR.
在本报告中，通过将Ni(Ac)·4HO与不对称的salen配体HL回流，制备了四种新型的Ni(II)-不对称salen配合物[NiL]。所有合成的配体和配合物均通过各种物理化学方法进行了表征。此外，通过单晶X射线衍射方法确定了[NiL]、[NiL]和[NiL]的固态结构。通过经济且环境友好的一锅三组分反应（使用试剂：1,3-二羰基化合物、丙二腈、苯甲醛或其衍生物）研究了[NiL]的催化潜力，用于合成具有生物活性的2-氨基-3-氰基-4-吡喃衍生物（共16种衍生物）。在优化反应条件后，以Ni(II)-不对称salen配合物为催化剂的这种新合成方案显示出优异的转化率，在1小时反应时间内有效催化产物的最大产率高达98%。此外，观察到作为环取代基含有吸电子基团的芳香醛显示出更好的转化率（高达98%），并且在优化的反应条件下，给电子基团取代基与苯甲醛相比显示出相似或更低的转化率。通过对所有这些Ni配合物结果的比较，发现催化性能的效率遵循[NiL]>[NiL]>[NiL]>[NiL]的顺序。通过紫外可见光谱预测并建立了可能的反应途径。反应途径中提出的中间体II也通过1H和13C NMR进行了捕获和表征。
