Current Organocatalysis - Volume 12, Issue 2, 2025

A novel immobilized imidazolium type ionic liquid was synthesized using poly(ethylene glycol) (PEG) functionalized magnetic multi-walled carbon nanotubes. This immobilized ionic liquid (MMWCNTs-PEG-IL) was characterized by FT-IR, VSM, XRD, FE-SEM and EDX analysis.

Then, it was used as a magnetic catalyst in a three-component reaction to yield tetrahydrobenzo[b]pyran derivatives. First, optimized reaction conditions were investigated. A mixture of containing dimedone (1 mmol), malononitrile (1 mmol), benzaldehyde (1.2 mmol) and MMWCNTs-PEG-IL (0.03 g) in H2O/EtOH (5 mL) was stirred at 70°C. After completion of the reaction, the mixture was cooled.

Then, an external magnet was used to separate the magnetic catalyst. This method has many advantages including high reaction yields, high TOFs, using non-toxic solvents, easy handling of catalyst, simple separation of catalyst from reaction medium and short reaction times.

Also, the reusability of the magnetic catalyst has been investigated in 7 runs without serious loss of reaction yield.

β-lactams have been primarily utilized as a leading class of effective antibiotics. They have been found to show activity against various diseases, prompting the scientific community to prioritise innovative protocols for their synthesis. The general and well-known synthetic strategy involves the classical Staudinger reaction exhibiting [2+2] cycloaddition reaction. However, the protocol utilizes stoichiometric excess of base for efficient product formation.

A smarter and more acceptable approach for the synthesis of β-lactams would be to reduce the excess base to a catalytic amount, furnishing a catalytic version of the Staudinger reaction. The modified version can eliminate the hazards arising out of excess use of the base, ultimately promoting the environmentally benign approach.

With this hypothesis, a base-catalyzed approach in dimethyl formamide (DMF) towards the synthesis of β-lactam via Staudinger reaction has been endorsed under moderate reaction conditions.

The scope of the substrates was explored with both electron-withdrawing and electron-releasing substitutions in the formation of β-lactam. The reduction of the base amount from stoichiometric to catalytic amount was justified by the involvement of DMF in generating the basic condition for the reaction.

It was hypothesized that the decomposition of DMF under the base-catalysed reaction condition can generate dimethylamine, which produces the required basic environment.

The Developed CuO-ZnO nanocomposite has been demonstrated as a new and environmentally friendly catalyst for one-pot multicomponent reaction between aldehydes, 2-naphthol and amides in the synthesis of 1-amidoalkyl-2-naphthols.

The new catalyst was synthesized by a ball-milling method by mixing a mixture of CuO and ZnO powder in various proportions and characterized by different spectroscopic methods such as powder X-ray diffraction (pXRD), Scanning Electron Microscopy (SEM), UV-Visible analysis, EDAX elemental analysis and mapping. The advantages of the devised protocol include a green approach, simple work-up procedures, avoidance of hazardous solvents, and good to excellent yields.

Evaluation of the catalyst performance in the synthesis of some 1-amidoalkyl-2-naphthols showed presentable results. Sixteen derivatives were synthesized in desirable yield by our new method (4a-4p). CuO-ZnO nanocomposite as a safe and efficient catalyst could be reused up to 5 runs for the synthesis of naphthol derivatives without any significant decrease in its potency.

The High purity of the products and desirable yields are other points that make the present work more attractive.

In this study, three amine-tethered DMAP cation bromide catalysts were prepared using two different mole ratios of 4-dimethylpyridine (DMAP) and 3-bromopropylamine hydrobromide (BPA·HBr) in two different solvents, namely, acetonitrile and ethanol. Then, prepared catalysts were employed for CO2 cycloaddition with styrene and propylene epoxides under metal- and solvent-free conditions.

The impact of mole ratio and solvent selection to prepare the designed product using a simple and cost-effective procedure was demonstrated systematically and was discussed in detail. Moreover, the influence of amine-tethered DMAP cation catalyst structures and reaction conditions on the cycloaddition was investigated, and the CO2 conversion proceeded smoothly at 80°C and 0.2 MPa for the synthesis of cyclic carbonates in good to excellent yields and high selectivity.

The current protocol could be a promising process at an industrial scale due to the high recyclability of the catalyst (10 cycles).

In summary, three catalytic systems bearing amine-tethered DMAP cation have been investigated for the chemical fixation of CO2 into five-membered cyclic carbonates at mild conditions.

Hydrazide derivatives were synthesized using an organocatalyst, offering an environmentally friendly approach characterized by shorter reaction times, mild conditions, and the use of green solvents.

The objective was to evaluate the synthesized compounds for their anti-tubercular activity against Mycobacterium tuberculosis (Mtb) and to assess the cytotoxicity of active compounds using the MTT assay.

Ultrasound energy was employed to facilitate the synthesis of the compounds. The resulting compounds were tested for their activity against Mycobacterium tuberculosis (Mtb), and the active compounds were further evaluated for cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl) -2,5- diphenyl tetrazolium bromide MTT assay.

Several compounds demonstrated activity against Mtb, with some derivatives exhibiting a Minimum Inhibitory Concentration (MIC) of 1.56 µg/mL, comparable to the standard anti-tubercular drug Ethambutol.

The eco-friendly synthesis of hydrazide derivatives shows significant potential in the development of anti-tubercular agents, with some compounds displaying efficacy similar to established drugs.

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.

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.

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.

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.

The synthesis of bisindolylalkanes has been carried out for more than two decades using several catalysts.

In the present study, naturally available orange juice has been demonstrated to be an efficient green catalyst for the synthesis of bisindolylalkanes from the reaction of indoles with different carbonyl compounds.

In this one-step process, the products were obtained with excellent yield and in a short reaction time.

This reaction-catalysed by orange juice is a new, inexpensive, and environment-friendly synthetic procedure for the preparation of bisindolylalkanes.