Current Organocatalysis - Current Issue

Dihydropyrimidinone (DHPM) is a very useful moiety with a wide range of applications. Synthesis of this moiety with environmentally friendly methods is the demand of the era.

In recent research, the optimisation of curd as a biocatalyst has been studied. It has been reported that it can be used directly in the multicomponent Biginelli synthesis of ethyl 6-methyl-2-oxo-4-benzyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates under mild reaction conditions.

The chemical structures of synthesized compounds were characterized by physicochemical and analytical methods (1H NMR, IR and LC-MS methods) and it was found that curd is suitable for a vast variety of aromatic aldehydes to obtain the corresponding DHPMs.

This new eco-friendly approach can be implemented to synthesize DHPMs for different applications.

Assessing the efficacy of remdesivir for COVID-19 infection holds historical significance. Understanding its effectiveness from previous pandemic instances can enable us to gain insights into its efficacy, informing our strategies for responding to future outbreaks or variants.

Gaining an insight into the historical efficacy of remdesivir can offer valuable data for evaluating the advancement of COVID-19 treatments and the development of medical expertise in handling the disease.

The historical data regarding the effectiveness of remdesivir can enrich the pool of knowledge and evidence accessible for public health planning and decision-making. Understanding whether remdesivir was efficacious in previous instances may aid in comprehending its real-world impact on patient outcomes at those times. Such insights are crucial for evaluating treatment efficacy and refining strategies based on past experiences.

In the late treatment of severe COVID-19 cases, which are particularly challenging, remdesivir has demonstrated a 6% improvement.

The 6% enhanced effect of remdesivir is not substantial, considering that it is an unweighted average of works with varying degrees of importance and reliability. Additionally, there are instances where conflicts of interest may have impacted the results. It is also possible that the observed improvement could be attributed to better patient care in certain environments.

In this study, the identification and quantification of biogenic amines in 45 commonly consumed food samples in Saudi Arabia were carried out. The enzymes responsible for producing these biogenic amines include spermidine (SPD), putrescine (PUT), tryptamine (TRP), tyramine (TYR), and histamine (HIS), which are synthesized through organo-catalytic pathways.

The diverse range of samples analyzed encompassed various types of beef, pickle varieties, canned fish, vegetables, chicken varieties, spices, fruits, and salad ingredients. Sample preparation involved the use of dansyl chloride after aqueous extraction, followed by isolation and analysis using reversed-phase HPLC with a UV detector. In five beef samples, mean concentrations of SPD, PUT, TRP, HIS, and TYR were identified as 9.41, 8.98, 155.8, 100.8, and 304.2 mg kg-1, respectively. Canned fish samples exhibited mean concentrations of TRP, PUT, HIS, TYR, and SPD at 71.6, 3.88, 29.2, 2.56, and 2.02 mg kg-1, respectively.

Among five pickle samples, mean concentrations of TRP, PUT, HIS, TYR, and SPD were reported as 118.8, 39.12, 35.2, 27.2, and 2.56 mg kg-1, respectively. Chicken samples primarily contained TRP, HIS, and SPD as the identified biogenic amines, with mean concentrations of 87.2, 105.6, and 5.22 mg kg-1, respectively. Fruit samples generally exhibited low levels of all enzymes except for TRP.

It was found that vegetables, seasonings, and salad ingredients either had undetectable or low quantities of biogenic amines.

MCRs are one of the most significant tools in the synthesis of organic compounds. MCR is a rapid chemical technique that uses three or more reactants to produce products that sustain all structural and substructural properties of the initial components. MCRs are useful in all fields of synthetic chemistry because of their rapid rate of reaction, simple procedure and excellent yields. We reported an efficient and environmentally friendly domino approach for the synthesis of spiroheterocycles spiro annulated with indeno[1,2-b]quinoline.

The spiroheterocycles with privileged heterocyclic substructures have been synthesized using taurine (2-aminoethanesulfonic acid) as a green, sustainable, bio-organic and recyclable catalyst in a three-component reaction of isatins, 1,3-diketones, and 1-napthylamine in aqueous media. The present synthetic method is probably the first report to synthesize spiroheterocycles, spiroannulated with indeno[1,2-b]quinoline. Furthermore, the approach is valuable because of the excellent yield that results from the reaction in 15-20 min.

The optimization of reaction conditions is an important case of efficient synthesis. The solvent, temperature, time and catalyst loading were all examined. The reusability of the catalyst was also investigated experimentally. The used catalyst taurine has a high activity as well as good reusability. The present synthetic protocol will be extended to synthesise a library of hybrid compounds. The present synthetic approach is cost-effective, and time-efficient with an easy-workup methodology that gives outstanding yields (80–95%) in 15–20 min.

Taurine-catalyzed multicomponent reaction is a novel and efficient method for the synthesis of spiroannulated indeno[1,2-b]quinolines. The high catalytic activity of taurine as a catalyst with water as a green solvent makes the process environmentally friendly. The special features of the synthetic protocol include synthetic efficiency, operational simplicity, and reusability of the catalyst and it is expected to make significant contributions not only to drug discovery studies but also to pharmaceutical and therapeutic chemistry in view of introducing molecular diversity in the synthesized molecules.

Knoevenagel condensation is an important C-C bond formation reaction catalyzed by various homogeneous and heterogeneous acid-base catalysts.

The present work describes the eco-friendly preparation of magnetic nanoparticles Fe3O4 (MNPs) and its functionalization to Fe3O4@SiO2@SO3H. The prepared MNPs and their functionalized materials were fully characterized by FT-IR, XRD, FE-SEM, HR-TEM, and VSM. Further demonstrated application of these catalysts for the C-C bond formation reactions of Knoevenagel condensation employing special aldehyde derivatives with malononitrile at room temperature gave excellent product isolation.

The application of the prepared functionalized MNPs for the Knoevenagel condensation was demonstrated by the reaction of various aryl/heterocyclic and cholesterol aldehyde with malononitrile at room temperature stirring for about 30 min in ethanol solvent. The final product isolated is confirmed by various spectroscopic techniques such as FT-IR, ¹H-, & ¹³C-NMR, and mass spectrometry. Furthermore, the selected compounds are screened for their photophysical properties, and interestingly compound 3j showed good fluorescent properties.

Overall the present work described a greener method preparation of MNPs, and its functionalized employed as a heterogeneous catalyst for the Knoevenagel condensation of various aryl/heterocyclic and cholesterol aldehyde with malononitrile. The method developed is simple, easily separated catalyst by an external magnet, and recycled up to five cycles without any noticeable change in the final product isolation. Further, the prepared derivatives screened for their photophysical properties, and interestingly compound 3j showed good fluorescent properties.