An overview of metal-free sustainable nitrogen-based catalytic knoevenagel condensation reaction

Abstract

Knoevenagel condensation reaction counts as a vital condensation in organic chemistry due to the synthesis of valuable intermediates, ‎heterocycles, and fine chemicals from commercially available reactants through forming new C=C...

Nanocage-based {In2Tm2}-organic framework for efficiently catalyzing the cycloaddition reaction of CO2 with epoxides and Knoevenagel condensation

“…6. 74–80 Firstly, the active sites of In 3+ , Tm 3+ , and μ 3 -OH ions contact with the O atoms of the aldehyde groups by van der Waals force or hydrogen bonds, weakening the CO bonds, and then the carbonyl carbon of malononitrile is activated by the N-pyridine atom to form an active imine intermediate. The imine intermediate tends to undergo a Knoevenagel condensation reaction with the weakened CO bond of aldehyde.…”

“…6. [74][75][76][77][78][79][80] Firstly, the active sites of In 3+ , Tm 3+ , and µ 3 -OH ions contact with the O atoms of the aldehyde groups by van der Waals force or hydrogen bonds, weakening the CvO bonds, and then the carbonyl carbon of malononitrile is acti-…”

Is a Catalyst Always Needed? The Case of the Knoevenagel Reaction with Malononitrile

“…Given its synthetic utility, a very large array of catalysts has been synthetized and tested. [7] A complete list of catalysts employed for the above reaction will be very long and, it is out of the scope of this Perspective. Nevertheless, such list ranges from very simple base such as hydroxide ions, simple amines, or amino acids, to ionic liquidbased catalysts, to a huge number of examples of heterogeneous materials and even nanomaterials.…”

“…From a mechanistic standpoint the reaction may take place through several pathways and the simplest way is the deprotonation of the active methylene compound, depending on the presence of a proper base and solvent. Given its synthetic utility, a very large array of catalysts has been synthetized and tested [7] …”

Microwave-assisted catalyst-free multicomponent one-pot green synthesis of highly functionalized aminocyanopyridines and (4-hydroxy)quinolines in aqueous medium and its in silico studies

“…In the synthesis of aminocyanopyridine, water was used to enhance the rate of the reaction by Anderson 7,8 and Sharpless. [9][10][11][12][13] Various types of reactions including Knoevenagel condensation, [14][15][16][17][18][19][20] 1,3-dipolar cycloaddition, [21][22][23][24][25] oxidationreduction, [26][27][28] nucleophilic substitution, [29][30][31][32] aldol, [33][34][35][36] Michael addition, 18,37 cross-coupling, 38,39 and multi-component reactions 1 have been attempted in water for green synthesis. However, multicomponent reactions enjoy fast development and outstanding status in organic 40,41 and medicinal chemistry for a high degree of atom economy and diversity-oriented convergent synthesis 42 of organic molecules and biologically important molecules using simple and readily available substrates.…”