Anudeep Kumar Narula

Carbohydrate chemistry remains a cornerstone of contemporary organic and medicinal chemistry owing to the structural complexity and biological significance of saccharides. However, traditional synthetic techniques are frequently limited by poor regio- and stereoselectivity, long reaction times, harsh reaction conditions, and a heavy dependence on protecting-group strategies and organic solvents. In recent years, non-conventional activation techniques have emerged as effective and sustainable alternatives for carbohydrate transformations. This review summarizes recent developments in mechanochemical, photochemical, microwave-assisted electrochemical, and continuous-flow methods. Mechanochemical techniques, especially ball milling, have been applied to glycosylation, protection-deprotection, and biomass valorization, enabling solvent-free or minimal-solvent reactions with increased efficiency, selectivity, and reduced environmental impact. Photochemical activation, including visible-light-mediated and photocatalyst-free methods, has enabled radical-driven, site-selective functionalization under mild conditions, facilitating access to structurally complex glycoconjugate. Microwave-assisted synthesis, through rapid and uniform heating, substantially shortens reaction times and increases yields. Electrochemical activation, which promotes transformations in glycosylated compounds by direct electron transfer at an electrode without stoichiometric chemical oxidants, and continuous-flow (microreactor) technology that increases heat and mass transfer, safety, and scalability compared with batch processing are also further emerging as complementary green tools and are increasingly being combined as ‘flow-electrochemical platforms’. Despite these advances, challenges remain, including limited substrate scope, scalability, inadequate mechanistic understanding, and the need for specialized equipment. Taken together, these non-conventional techniques offer effective, sustainable, and adaptable alternatives to standard methods in carbohydrate synthesis, and are reshaping the field.

Triazoles have emerged as versatile linkers in carbohydrate chemistry, enabling the construction of stable and multifunctional glycohybrids. This review explores the use of triazoles in carbohydrate chemistry, focusing on how they can be used to create versatile compounds with applications in both medicine and materials science. A variety of glyco-triazole hybrids have been synthesized using efficient and sustainable click chemistry methods. These methods allow for the high-yield joining of sugars to other molecules under biocompatible conditions. This review highlights the diverse biological activities of these new compounds, including their use as antimicrobial, antifungal, and anticancer agents. A cationic chitosan derivative with triazole and quaternary ammonium groups showed strong antifungal and antioxidant properties. Other examples include carbohydrate-derived triazoles that inhibit glycogen phosphorylase, a feasible treatment for type 2 diabetes, and piperazine triazolyl sugar conjugates that show potent anticancer activity against HeLa cells. Beyond their medicinal uses, the review also covers the application of glyco-triazole hybrids in materials science and sensing. This review emphasises that while significant progress has been made, future work should focus on designing more complex structures, using greener synthesis methods, and addressing challenges like bioavailability and stability to move these promising compounds from the laboratory to real-world applications.

Since the discovery of N‐heterocyclic carbenes (NHCs), their role as ligands and organocatalysts has grown significantly due to their unique umpolung reactivity and strong σ‐donor capabilities. In recent years, the field of amide bond formation has seen notable advancements through NHC catalysis. Given the wide application of amides in pharmaceuticals, agrochemicals, and materials science, several NHC‐based strategies have emerged for synthesizing amides from substrates such as aldehydes, alcohols, esters, and nitriles. This review highlights the sustainable and efficient nature of NHC‐catalyzed amide bond formation. Both metal–NHC complexes and metal‐free NHCs offer diverse catalytic pathways, with Ru–NHC systems proving especially effective in redox‐neutral amidations. NHCs promote reactions through mechanisms involving acyl azolium, hemiaminal, and Breslow intermediates, enabling high selectivity under mild conditions. Many of these methods align with green chemistry principles, featuring high atom economy and minimal waste generation. The versatility and tunability of NHC catalysts allow broad substrate compatibility, and recent innovations include metal‐free organocatalysis, continuous flow processes, and electrochemical amidation strategies. This review presents a comprehensive analysis of NHC‐catalyzed amide formation, summarizing key mechanisms, substrate scope, and catalyst design, emphasizing their dual role in metal‐based and organocatalytic sustainable amidation methods.

Background: Mono- and bis-(1,4-disubstituted-1,2,3-triazoles) were synthesized via a laccase-catalyzed reaction using Trametes versicolor. This methodology offers a convenient and efficient approach to triazole synthesis under mild conditions, achieving modest to good yields. Additionally, molecular docking studies were performed using PDB IDs 2W9S (antibacterial) and 3KHM (antifungal) to evaluate biological activities. The results of drug-likeness analysis further corroborated the findings from experimental biological evaluations. Methods: This study focuses on developing an eco-friendly method for synthesizing novel 1,2,3- triazole derivatives using a green catalyst. A co-solvent buffer and organic solvent facilitate the reaction, which performs well with various substrates, including substituted benzenes (-ortho, -meta & para-mono & bis-(2-propynyloxy), sodium azide, and aryl halides. Laccase enzymes from Trametes versicolor are used, leveraging naturally occurring copper metals instead of external transition metals, bound through histidine, methionine, and cysteine linkages. This method represents a sustainable approach to organic transformations. Result: New scaffolds of mono- and bis-(1,4-disubstituted-1,2,3-triazoles) were synthesized using eco-friendly green buffer solvents and laccase catalysis with aryl halides, sodium azide, and acetylene derivatives. Molecular docking studies revealed that the binding affinities of the synthesized compounds (1-14) show promising interactions with antibacterial and antifungal proteins. All others except for compounds 6, 7, 8, 12, and 13, meet Lipinski’s criteria, making them potential therapeutic candidates. Conclusion: In conclusion, this methodology is valuable for developing antibacterial and antifungal agents in medicinal chemistry. Additionally, microwave-assisted synthesis of (2-propenyloxy)benzene derivatives significantly reduced reaction times from hours to minutes. The approach is environmentally friendly and practical, particularly for handling flammable organic azides and hazardous solvents, making it both efficient and safer.

A novel green efficient methodology was developed for the synthesis of some regioselective 1,4‐disubstituted‐1,2,3‐triazoles through an enzyme laccase ( Trametes Versicolor ) catalyzed reaction. The reaction utilizes the Click chemistry approach for the formation of highly substituted and regioselective triazoles. The methodology is unprecedented in the way that it executes under mild conditions at room temperature using green buffer solvents. An array of substituted triazoles were feasibly synthesized and characterized via spectroscopic techniques.

New candidates of imidazo[1,2-a]pyridine were designed by combining 2-amino pyridine, TOSMIC and various assorted aldehydes to explore their antioxidant and antifungal potential. The design of these derivatives was based on utilizing the antifungal potential of azoles and TOSMIC moiety. These derivatives were synthesized by adopting multi-component reaction methodology, as it serves as a rapid and efficient tool to target structurally diverse heterocyclic compounds in quantitative yield. The resulting imidazo[1,2-a]pyridine derivatives were structurally verified by ¹HNMR, ¹³CNMR, HRMS, and HPLC. The compounds were analyzed for their antioxidant and fluorescent properties and it was observed that compound 15 depicted highest potential. The compounds were evaluated for their antifungal potential to highlight their medical application in the area of Invasive Fungal Infections (IFI). Compound 12 gave the highest antifungal inhibition against Aspergillus fumigatus 3007 and Candida albicans 3018. To elucidate the antifungal mechanism, confocal images of treated fungi were analyzed, which depicted porous nature of fungal membrane. Estimation of fungal membrane sterols by UPLC indicated decrease in ergosterol component of fungal membrane. In silico studies further corroborated with the in vitro results as docking studies depicted interaction of synthesized heterocyclic compounds with amino acids present in the active site of target enzyme (lanosterol 14 alpha demethylase). Absorption, distribution, metabolism, and excretion (ADME) analysis was indicative of drug-likeliness of the synthesized compounds.