An Effective One-Pot Access to 2-Amino-4H-benzo[b]pyrans and 1,4-Dihydropyridines via γ-Cyclodextrin-Catalyzed Multi-Component Tandem Reactions in Deep Eutectic Solvent

Graphene oxide immobilized 2-morpholinoethanamine as a versatile acid-base catalyst for synthesis of some heterocyclic compounds and molecular docking study

In this study, a new heterogeneous catalyst was synthesized based on graphene oxide (GO) as a natural material. On the surface of nanosheet graphene oxide, 2-Morpholinoethanamine was immobilized using a non-toxic, green, and simple method. This resulted in the preparation of a bifunctional acid-base nanocatalyst. The synthesized composite was fully characterized using various methods, including Fourier transform infrared spectrometry (FT-IR), scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), mapping, Raman spectroscopy, X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and CHN elemental analysis. The catalytic reactivity of GO-mor was investigated in the one-pot synthesis of some benzo[b]pyran, pyrano[3,2-c]chromene, and polyhydroquinoline derivatives, yielding good efficiency and short reaction times. In addition, several recent studies have shown that some derivatives of pyran, chromene, and quinoline have remarkable anti COVID activity. Particularly, COVID-19 3CLpro/Mpro is considered a potential target for the treatment of this virus. For this purpose, docking models were constructed using the corresponding crystal structures with the synthesized derivatives. Based on the docking score and similarity of the binding mode to remdesivir and elvitegravir (the only approved drugs for the treatment of COVID-19), A2, B1, and C4 were selected as promising candidates for further research.

Construction of 1,4-Dihydropyridines: The Evolution of C4 Source

The field of cascade cyclization for the construction of 1,4-dihydropyridines (1,4-DHPs) has been continuously expanding during the last decades because of their broad-spectrum biological and synthetic importance. To date, many methods have been developed, mainly including the Hantzsch reaction, Hantzsch-like reaction and newly developed cascade cyclization, in which various synthons have been successively developed as C4 sources of 1,4-DHPs. This review presents the cascade cyclization synthesis strategy for the construction of 1,4-DHPs according to various C4 sources from carbonyl compounds, alkenyl fragments, alcohols, aliphatic amines, glycines and other C4 sources.

Neoteric deep eutectic solvents: history, recent developments, and catalytic applications

Deep eutectic solvents (DESs) are modified versions of ionic liquids (ILs) and are formed by the fusion of polar components (liquids or solids) via hydrogen bonding interactions. DESs are prepared by the simple mixing of two or three cheap constituents (that are capable of self-association) with gentle heating, which leads to a drastic decrease in their melting points. The resultant clear homogeneous mixture consists of cations, anions, as well as neutral molecules; this will contribute both ionic and molecular solvent properties to the DESs. DESs have emerged as alternatives to conventional organic solvents and ILs, which meet different criteria such as availability, low cost, low toxicity, biodegradability, recyclability, ease of preparation method, tunable, and designer physiochemical properties. Many of them have attracted considerable attention and haave been applied in distinct fields of chemistry. To summarize the full-scale development of DESs, this review discusses the history, classifications, various methods of preparation, properties, and some major applications in catalysis in the last three years. This review is expected to be helpful for the further development of DESs based on a summary of the fundamental research in the field.

Synthesis of Core-Shell Magnetic Supramolecular Nanocatalysts based on Amino-Functionalized Calix[4]arenes for the Synthesis of 4H-Chromenes by Ultrasonic Waves

One of the most common phenol-formaldehyde cyclic oligomers from hydroxyalkylation reactions that exhibit supramolecular chemistry are calixarenes. These macrocyclic compounds are qualified to act as synthetic catalysts due to their specific features including being able to form host-guest complexes, having unique structural scaffolds and their relative ease of chemical modifications with a variety of functions on their upper rim and lower rim. Here, a functional magnetic nanocatalyst was designed and synthesized by using a synthetic amino-functionalized calix[4]arene. Its catalytic activity was evaluated in a one-pot synthesis of 2-amino-4H-chromene derivatives. Besides, this novel magnetic nanocatalyst was characterized by spectroscopic and analytical techniques such as FT-IR, EDX, FE-SEM, TEM VSM, XRD analysis.

Dihydropyridines as potential α-amylase and α-glucosidase inhibitors: Synthesis, in vitro and in silico studies

Dihydropyridine derivatives 1-31 were synthesized via one-pot solvent free condition and screened for in vitro against α-amylase and α-glucosidase enzyme. The synthetic derivatives 1-31 showed good α-amylase inhibition in the range of IC50 = 2.21 ± 0.06-9.97 ± 0.08 µM, as compared to the standard drug acarbose (IC50 = 2.01 ± 0.1 µM) and α-glucosidase inhibition in the range of IC50 = 2.31 ± 0.09-9.9 ± 0.1 µM as compared to standard acarbose (IC50 = 2.07 ± 0.1 µM), respectively. To determine the mode of binding interactions of synthetic molecules with active sites of enzyme, molecular docking studies were also performed. Different spectroscopic techniques such as 1H, 13C NMR, EI-MS, and HREI-MS were used to characterize all the synthetic compounds.

Mekheimer R, M. Hayallah A, A. Abo Elsoud F, U. Sadek K. Recent Advances in the Utility of Glycerol as a Benign and Biodegradable Medium in Heterocyclic Synthesis

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Glycerol is a non-toxic, recyclable and biodegradable organic waste produced as a byproduct in the production of biodiesel fuel. Currently, glycerol is considered a green solvent and catalyst for a large variety of applications. This work discusses the significance of glycerol for heterocyclic synthesis. All the reported studies consider glycerol as an efficient and sustainable benign medium.

New Hydrogen-Bond-Enriched 1,3,5-Tris(2-hydroxyethyl) Isocyanurate Covalently Functionalized MCM-41: An Efficient and Recoverable Hybrid Catalyst for Convenient Synthesis of Acridinedione Derivatives

A new nano-ordered 1,3,5-tris(2-hydroxyethyl) isocyanurate-1,3-propylene covalently functionalized MCM-41 (MCM-41-Pr-THEIC) was designed and prepared at room temperature through a simple procedure. According to various microscopic, spectroscopic, or thermal methods and techniques, the correlation of the catalytic performance of the hybrid mesoporous MCM-41-Pr-THEIC to its structural characteristics was fully confirmed. The new MCM-41-Pr-THEIC organosilica nanomaterials were successfully investigated as a solid mild nanocatalyst through hydrogen-bonding activation provided by its organic moiety, for the pseudo-four-component condensation of dimedone, aldehydes, and ammonium acetate or p-toluidine to afford the corresponding acridinedione derivatives under green conditions. Furthermore, the introduced nanocatalyst could be reused at least four times with negligible loss of its activity, indicating the good stability and high activity of the new hybrid organosilica.