Current Organocatalysis - Online First

Introduction

Organic azides are valuable precursors of 1,2,3-triazoles, a class of heterocyclic compounds with broad biological relevance and diverse applications as functional materials. The understanding of the electronic effects of substituents on azide reactivity is crucial for optimizing copper(I)-catalyzed azide–alkyne cycloaddition processes.

Methods

A series of 1,2,3-triazoles were synthesized via copper(I)-catalyzed azide–alkyne cycloaddition employing microwave radiation as an alternative energy source. Computational studies were performed using Molecular Electrostatic Potential maps and the dual descriptor at the B3LYP/6-311G(d,p) level of theory to analyze the electronic structure of the aromatic azides employed as precursors of 1,2,3-triazoles.

Results

Compounds 3a and 3e-g were obtained in moderate to good yields (72-78%), whereas strongly electron-withdrawing substituents avoided the formation of products 3b-d. The computational analysis revealed differences in the distribution charge on the azide group.

Discussion

The absence of products 3b-d is attributed to the presence of strong electron-withdrawing substituents. According to the dual descriptor, the formation of the metallacycle between azide and alkyne is favored when Nb and Ng exhibit predominantly electrophilic and nucleophilic characters, respectively, which promotes the mesomeric effect of the azide.

Conclusion

The molecular electrostatic potential maps and dual descriptor revealed that for the evaluated compounds, electron-withdrawing substituents modify the distribution of the electronic density on the azide group. The phenylazides with enhanced positive character at Nβ and higher electron density at Nγ showed better reactivity toward triazole formation. The integration of experimental and computational approaches provides insights into the electronic effects in azide reactivity and supports the design of 1,2,3-triazole compounds.

Introduction

Benzimidazole and its derivatives are among the most popular structures used in pharmaceutical and medicinal chemistry for drug discovery, particularly within the wide variety of heterocycles. Benzimidazole has a preferred structure in drug discovery due to its distinct structural characteristics and the diverse biological actions of its derivatives.

Methods

This study highlights the significance of this moiety due to its broad range of biological features and the widespread use of benzimidazole.

Results

This review consolidates extensive research conducted from 1990 to 2025, highlighting benzimidazole derivatives as key pharmacophores across diverse therapeutic areas. Benzimidazole compounds exhibit multifaceted anti-inflammatory, analgesic, antiviral, anticancer, antioxidant, and anthelmintic activities, indicating their systemic benefits.

Discussion

In many drugs used to treat conditions such as cancer, microbial infections, inflammatory disorders, hypertension, and malaria, the benzimidazole ring structure exhibits a broad range of pharmacological activity. Additionally, this fused heterocycle benzimidazole core may interact with various anions and cations, as well as biomolecules, in the human body to produce a range of biological activities, including antidepressant, antiviral, antibacterial, antifungal, anti-inflammatory, and analgesic effects.

Conclusion

This review focuses on benzimidazole derivatives and their effects on different sites of action, as well as contemporary developments in drug design and development.

Background

Sulfonated carbon (C-SO3H) nano/micro powder derived from waste biomaterial offers a green catalytic approach in several chemical transformations due to its good performance and reusability. In this report, we synthesized carbon powder from waste litchi peels (LPC) and integrated it with sulfonic acid to obtain LPC-SO3H as a heterogeneous solid acid catalyst.

Objective

The objective of this work is the development of a biowaste-derived solid acid catalyst and the investigation of its catalytic application in the synthesis of 4-(substituted phenylamino)-2H-chromen-2-ones.

Methods

The LPC-SO3H was synthesized by first pyrolyzing waste litchi peel at 400°C for approximately 2 hours, followed by sulfonation with concentrated H2SO4. The prepared LPC-SO3H was characterized by XRD, FT-IR, SEM-EDX, and XPS binding studies. The catalytic application of LPC-SO3H powder was evaluated for the synthesis of 4-(substituted phenylamino)-2H-chromen-2-ones under microwave irradiation.

Results

The characterization techniques confirmed the formation of LPC-SO3H, and acid-base titration showed the total acidity of LPC-SO3H to be 2.05 mmol/g.

Conclusion

The LPC-SO3H powder was found to be a good, recyclable catalyst for the synthesis of the targeted 4-(substituted phenylamino)-2H-chromen-2-ones with a simple work-up procedure

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