Letters in Organic Chemistry - Volume 21, Issue 7, 2024

Biodiesel and oleo-chemical industries have been producing huge quantities of glycerol as a by-product. Value-added products can be synthesized from glycerol through different chemical and enzymatic reactions, such as oxidation, carbonylation, reforming, acetalyzation, etherification, dehydration, hydrogenolysis, hydrolysis, esterification, and transesterification. Glycerol is a low-cost polyol that can be converted into glycerol carbonate, which has potential applications in polymer and biobased non-isocyanate polyurethanes industries (Bio-NIPUs). The present contribution is the first of its kind to report on the synthesis of glycerol carbonate via catalyst and solvent-free transesterification of glycerol with dimethyl carbonate under conventional as well as microwave heating. Additionally, a comparative study of conventional and microwave-assisted transesterification was performed. Under conventional heating, 78% glycerol carbonate is obtained at 120^oC in 36 hours, whereas, using microwaves, 92% of glycerol carbonate can be achieved in 30 minutes. Presently, biomass-based heterogeneous materials are used in catalysis due to their importance within the context of sustainability. In line with this, in this work, a series of green catalysts, namely, molecular sieves (MS, 4Å), Hβ- Zeolite, Montmorillonite K-10 clay, activated carbon prepared from the shell of groundnut (Arachis hypogaea), and biochar from sawdust pyrolysis were successfully employed. Glycerol carbonate was thoroughly characterized by ¹H and ¹³C NMR, FT-IR and MS. The method described here is facile and green since the utilization of bioresource (glycerol) for the production of glycerol carbonate is performed under microwave.

In the carbamate Schiff base compound, the molecule is stabilized by intramolecular hydrogen bonding interactions along with π···π stacking and C–H···π contacts that lead to the molecule generating diverse supramolecular architecture. The fingerprint plots associated with Hirshfeld surface analysis indicate that the most important contributions for the crystal packing are from HH/HH (81.8%), HO/OH (7.5%), and HN/NH (1.9%) interactions. Furthermore, a computational study is performed to find the interaction energy between molecular pairs, and a description of the active site of the compound has been included. The study inferred the role of various types of interaction energies in stabilizing the molecular pair. Additionally, the carbamate Schiff base compound was tested as a possible inhibitor for a group of the SARS-CoV-2 proteins employing a molecular docking approach. Papain-like protease (PLpro) was shown to have the highest binding affinities. The carbamate Schiff base compound with PLpro’s docking score falls within the acceptable levels for a hit compound.

Our primary research objective is to create and formulate small ring heterocycles with enhanced biological efficacy. Amide functionalized trifluoromethyl thieno[2,3-b]pyridine derivatives as a series were prepared starting from reaction between 1,3 di-ketone and thiocyanoacetamide and obtained pyridine 3. Compound 3 reacts with bromoethyl acetate and obtained compound 4, further compound 4 on reaction with diverse substituted aromatic and aliphatic amines to get amide derivatives 5a-d, 6a-d and 7a-h. All the final compounds evaluated for anti cancer activity against four human cancer cell lines such as ‘HeLa - Cervical cancer (CCL-2); COLO 205- Colon cancer (CCL- 222); HepG2 - Liver cancer (HB-8065); MCF7 - Breast cancer (HTB-22)’ and promising compounds 7d, 7e and 7f have been identified. For compounds 7d, 7e and 7f molecular docking interactions have been identified.

>Lipid esters are prepared from mixed fatty anhydrides by esterification. These esters are high-value-added intermediates used in industrial applications. We describe the synthesis and characterization of esters using salicylic acid and mixed anhydrides with zinc oxide as catalysts. To achieve maximum reaction efficiency, we varied the mixed anhydride and studied some parameters in the reaction, such as the molar ratio (anhydride/alcohol) and the amount of catalyst. The esterification reaction was realized with some primary and secondary alcohols in the presence of resin Amberlyst- 15. The best yield of the palmitic ester was obtained in the case of mixed 4-chlorobenzoic palmitic anhydride. We obtained 53% of fatty ester. Moreover, we also studied the reactivity of certain mixed anhydrides for the esterification reaction of salicylic acid in the presence of a Lewis acid as a heterogeneous catalyst. The anhydrides were prepared in the presence of triethylamine in the organic solvent by a reaction between fatty acid and acid chloride. Mixed aromatic palmitic were more reactive and selective than the aliphatic anhydrides. The palmitic group was the most involved in acylation. Good yields of fatty esters were obtained with total conversion of mixed anhydrides.

A variety of dihydropyrimidone compounds were synthesised using an effective one-pot, multicomponent, environmentally friendly reaction of aromatic aldehydes, urea/thiourea, ethyl acetoacetate, and glycerol/ethyl lactate. To the best of our knowledge, this is the first catalyst-free strategy for the synthesis of this key scaffold with medicinal chemistry applications. Other significant aspects of the current approach consist of the employment of glycerol/ethyl lactate as a biodegradable and environmentally friendly reaction medium-cum-promoter, the use of easily available substrates, moderate reaction conditions, ease of use, a wide substrate scope, a short reaction time, easy workup, and excellent yields, and atom efficiency, which make the disclosed procedure an excellent alternative to existing methods.

In this study, high yields of various cyclic carbonates are obtained by employing the drug celecoxib to promote the coupling reaction of CO2 and epoxide using tetrabutylammonium bromide. This strategy enables the synthesis of benzoic acid, phenylpropiolic acid, and 2, 4- quinazolinedione. In addition, the model reaction mechanism is proposed.

A protocol for the Chemoselective N-Boc protection of various types of amines has been developed. This includes heteroaryl, aliphatic, and alicyclic amines. The process makes use of malic acid as a catalyst and operates efficiently at ambient temperature without the need for solvents. This technique has been proven to effectively protect a wide range of functionalized amines containing both electron-donating and electron-withdrawing substituents. The benefits of this method include its fast reaction rate, high selectivity, excellent yield, catalyst recyclability, and environmentally friendly conditions.

In the current work, the Electro-Fenton (EF) based Reactive Orange 16 (RO16) dye treatment was studied and compared with central composite (CC) and Taguchi design (TD) statistical optimization tools. Color removal (RC) and COD decay (RCOD) were chosen responses for the effect of pH (A), electrolysis time (B), initial dye concentration (C), and current density (D). The facecentred CC design and L16 orthogonal array were used in the experimental procedures. At optimal conditions, the coefficient of determination (R²) values of 0.99 for CC and 0.97 for TD suggest statistical significance and good model agreement. The results of the ANOVA and Prob. > F values supported the model’s successful experimental data fitting. Taguchi method was found as an appropriate methodology for parameter percentage contributions with fewer experimental runs. Moreover, the S/N ratio charts proved to be a successful CC design replacement. The current density and pH were found to be the most important factors for the EF process. A higher biodegradability (BOD5/COD) and minimum iron concentration (0.45 mg/L) in the effluent sludge demonstrated good environmental disposal suitability. In the last, the effect of various inhibitors/scavengers (SO4⁻², PO4⁻³, EDTA, etc.) on the EF process performance was also carried out.

Similar affiliation error appeared in the author's affiliation in the article entitled “Review on Pyrazole Hybrids as Anti-microbial Agents”, published in Letters in Organic Chemistry, 2024, 21(4), 320-332 [1]. Details of the error and a correction are provided here. Original: Author Affiliation: ¹Department of Pharmaceutical Chemistry, Bharati Vidyapeeth (Deemed to be) University, Poona College of Pharmacy, Pune, India; ²Department of Pharmaceutical Chemistry, Bharati Vidyapeeth (Deemed to be) University, Poona College of Pharmacy, Pune, India Corrected: Author Affiliation: ¹Department of Pharmaceutical Chemistry, Bharati Vidyapeeth (Deemed to be) University, Poona College of Pharmacy, Pune, India We regret the error and apologize to readers. The original article can be found online at https://www.eurekaselect.com/article/133287