Design of Promising Thiazoloindazole-Based Acetylcholinesterase Inhibitors Guided by Molecular Docking and Experimental Insights

Alzheimer's disease is characterized by a progressive deterioration of cognitive function and memory loss, and it is closely associated with the dysregulation of cholinergic neurotransmission. Since acetylcholinesterase (AChE) is a critical enzyme in the nervous system, responsible for breaking down the neurotransmitter acetylcholine, its inhibition holds a significant interest in the treatment of various neurological disorders. Therefore, it is crucial to develop efficient AChE inhibitors capable of increasing acetylcholine levels, ultimately leading to improved cholinergic neurotransmission. The results reported here represent a step forward in the development of novel thiazoloindazole-based compounds that have the potential to serve as effective AChE inhibitors. Molecular docking studies revealed that certain of the evaluated nitroindazole-based compounds outperformed donepezil, a well-known AChE inhibitor used in Alzheimer's disease treatment. Sustained by these findings, two series of compounds were synthesized. One series included a triazole moiety (Tl45a-c), while the other incorporated a carbazole moiety (Tl58a-c). These compounds were isolated in yields ranging from 66 to 87% through nucleophilic substitution and Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reactions. Among the synthesized compounds, the thiazoloindazole-based 6b core derivatives emerged as selective AChE inhibitors, exhibiting remarkable IC50 values of less than 1.0 μM. Notably, derivative Tl45b displays superior performance as an AChE inhibitor, boasting the lowest IC50 (0.071 ± 0.014 μM). Structure-activity relationship (SAR) analysis indicated that derivatives containing the bis(trifluoromethyl)phenyl-triazolyl group demonstrated the most promising activity against AChE, when compared to more rigid substituents such as carbazolyl moiety. The combination of molecular docking and experimental synthesis provides a suitable and promising strategy for the development of new efficient thiazoloindazole-based AChE inhibitors.

Electrochemical Cyclization of o-Aminyl Azobenzenes: Roles of Aldehydes in N-N Bond Cleavage

Direct functionalization of azobenzenes provides an approach to obtaining valuable molecules in synthetic chemistry. However, an efficient method for the cleavage of the N═N bond of azobenzenes, which is a key process for this transformation, is still lacking. We herein disclose an electrochemical reduction-induced cyclization of azobenzenes with aldehydes via N═N bond cleavage. This electrochemical cyclization of azobenzenes proceeds well in the absence of any transition metals or external chemical oxidants, leading to the formation of N-protected benzimidazoles in moderate to good yields.

AgNOx as Nitrogen Source for [1+1+3] Cycloaddition of Isocyanides with Isocyanates: Selective Synthesis of 1,2,4-Triazoles

A novel [1+1+3] annulation of AgNOx, isocyanides, and isocyanates for the selective synthesis of 1,2,4-triazoles is presented herein. In this transformation, AgNOx and isocyanates are used as nitrogen sources instead of the traditional hydrazine or diazonium reagents. This process also involves N-O/C-H/C═N bond cleavage and the construction of new N-N/C-N bonds with a good substrate scope and functional group tolerance.

Molybdenum-catalyzed deoxygenative heterocyclization of 2-nitroazobenzenes: a novel strategy for catalytic synthesis of 2-aryl-2H-benzo[d][1,2,3]triazoles

A novel strategy for the catalytic synthesis of 2-aryl-2H-benzo[d][1,2,3]triazoles bearing a wide range of functional groups in good to excellent yields by non-noble molybdenum-catalyzed deoxygenative heterocyclization of 2-nitroazobenzenes is described. The salient features of the transformation include the use of readily available substrates, valuable products and ease of scale-up. The mechanistic study indicates that the reaction occurred via double deoxygenation by the Mo(VI)/Mo(IV) catalytic cycle from 2-nitroazobenzene, through the formation of 2-aryl-2H-benzo[d][1,2,3]triazole-N1-oxide or nitrene intermediates.

Selective C3-nitrosation of imidazopyridines using AgNO3 as the NO source

We developed a novel method for selective radical nitrosation of imidazo[1, 2-a]pyridine derivatives using AgNO3 as a NO source.

AgNO3 as Nitrogen Source for Cu-Catalyzed Cyclization of Oximes with Isocyanates: A Facile Route to N-2-Aryl-1,2,3-triazoles

A versatile copper-catalyzed [3 + 1 + 1] annulation of oximes and isocyanates with AgNO₃ is described. In this conversion, AgNO₃ and isocyanates instead of conventional azide or diazonium reagents were used as the nitrogen source. This three-component transformation was achieved by cleaving N-O/C-H/C-N bonds and building C═N/N-N bonds, which provides a strategy to prepare N-2-aryl-1,2,3-triazoles with a good substrate and functional compatibility.

Dual Functional Pd-Catalyzed Multicomponent Reaction by Umpolung Chemistry of the Oxygen Atom in Electrophiles

A Pd-catalyzed multicomponent reaction was developed by trapping oxomium ylide with nitrosobenzene via Pd-promoted umpolung chemistry. The Pd catalyst plays two important roles: diazo compound decomposed catalyst and Lewis acid for the activation of nitrosobenzene. This strategy provides some insight into a new way for discovery of multicomponent methodology to construct complex molecules. The developed method also provides rapid access to a series of O-(2-oxy) hydroxylamine derivatives, which exhibit good anticancer activity in osteosarcoma cells.

Modification of Azobenzenes by Cross-Coupling Reactions

Azobenzenes are among the most extensively used molecular switches for many different applications. The need to tailor them to the required task often requires further functionalization. Cross-coupling reactions are ideally suited for late-stage modifications. This review provides an overview of recent developments in the modification of azobenzene and its derivatives by cross-coupling reactions.

1 Introduction

2 Azobenzenes as Formally Electrophilic Components

2.1 Palladium Catalysis

2.2 Nickel Catalysis

2.3 Copper Catalysis

2.4 Cobalt Catalysis

3 Azobenzenes as Formally Nucleophilic Components

3.1 Palladium Catalysis

3.2 Copper Catalysis

3.3 C–H Activation Reactions

4 Azobenzenes as Ligands in Catalysts

5 Diazocines

5.1 Synthesis

5.2 Cross-Coupling Reactions

6 Conclusion

Selective and Scalable Electrosynthesis of 2H-2-(Aryl)-benzo[d]-1,2,3-triazoles and Their N-Oxides by Using Leaded Bronze Cathodes

Electrosynthesis of 2H-2-(aryl)benzo[d]-1,2,3-triazoles and their N-oxides from 2-nitroazobenzene derivatives is reported. The electrolysis is conducted in a very simple undivided cell under constant current conditions with a leaded bronze cathode and a glassy carbon anode. The product distribution between 2H-2-(aryl)benzo[d]-1,2,3-triazoles and their N-oxides can be guided by simply controlling the current density and the amount of the charge applied. The reaction tolerates several sensitive functional groups in reductive electrochemistry. The usefulness and the applicability of the synthetic method is demonstrated by a formal synthesis of an antiviral compound.

Rh(iii)-Catalyzed regioselective mono- and di-iodination of azobenzenes using alkyl iodide

We developed a highly chemoselective oxidative access to ortho-iodinated azobenzenes by Rh(iii)-catalysis with alkyl iodide as the iodinating reagent.

tert-Butyl nitrite (TBN) as the N atom source for the synthesis of substituted cinnolines with 2-vinylanilines and a relevant mechanism was studied

A green method to synthesize cinnolines by 6π electrocyclic reaction with alkenyl amines and TBN has been developed.

AgNO2 as the NO Source for the Synthesis of Substituted Pyrazole N-Oxides from N-Propargylamines

A straightforward method for synthesizing the pyrazole N-oxides from N-propargylamines and AgNO₂ through oxidation/cyclization reaction had been developed. AgNO₂ was used as the NO source for the first time to synthesize pyrazole N-oxides. Various substituted groups on N-propargylamines proceeded smoothly, and the desired products were obtained in good yields.