An ultrasound-assisted solvent and catalyst-free synthesis of structurally diverse pyrazole centered 1,5-disubstituted tetrazoles via one-pot four-component reaction

1,5-Disubstituted tetrazoles are vital drug-like scaffold usually encountered as valuable bioisosteres of cis-amide bond. In this article, we reported synthesis of some novel medicinally relevant pyrazole centered 1,5-disubstituted tetrazoles using ultrasound irradiation via a one-pot 4-C reaction from various pyrazole originated aldehyde, amine, isocyanide, and sodium azide. All the synthesized derivatives were characterized by IR, 1H NMR, 13C NMR, spectroscopic techniques, and mass analysis. This ultrasound-assisted green protocol has several advantages like mild reaction condition, high yield, catalyst and solvent-free reaction protocol, 15 minutes reaction time and easy workup.

A new series of 2,4-thiazolidinediones endowed with potent aldose reductase inhibitory activity

In an effort to identify potent aldose reductase (AR) inhibitors, 5-(arylidene)thiazolidine-2,4-diones (1–8), which were prepared by the solvent-free reaction of 2,4-thiazolidinedione with aromatic aldehydes in the presence of urea, were examined for their in vitro AR inhibitory activities and cytotoxicity. 5-(2-Hydroxy-3-methylbenzylidene)thiazolidine-2,4-dione (3) was the most potent AR inhibitor in this series, exerting uncompetitive inhibition with a K i value of 0.445 ± 0.013 µM. The IC50 value of compound 3 for L929 mouse fibroblast cells was determined as 8.9 ± 0.66 µM, pointing out its safety as an AR inhibitor. Molecular docking studies suggested that compound 3 exhibited good affinity to the binding site of AR (PDB ID: 4JIR). Based upon in silico absorption, distribution, metabolism, and excretion data, the compound is predicted to have favorable pharmacokinetic features. Taking into account the in silico and in vitro data, compound 3 stands out as a potential orally bioavailable AR inhibitor for the management of diabetic complications as well as nondiabetic diseases.

Microwave Assisted Envirocat EPZ-10 Catalyzed Multi-component Synthesis of 1-Amidoalkyl-2-naphthols

Microwave assisted catalytic efficiency of Envirocat EPZ-10 was explored in solvent free green synthesis of 1-amidoalkyl-2-naphthols by the reaction of aldehyde, 2-naphthol and acetamide. The products formed were characterized by spectroscopic methods such as NMR, IR and mass spectroscopy. The merits of developed synthetic method are use of Envirocat EPZ-10 as eco-friendly, reusable and heterogeneous catalysts, solvent-free reaction, shorter reaction time and easy isolation of product.

An Alginate-Confined Peroxygenase-CLEA for Styrene Epoxidation

Oxyfunctionalisation reactions in neat substrate still pose a challenge for biocatalysis. Here, we report an alginate-confined peroxygenase-CLEA to catalyse the enantioselective epoxidation of cis-β-methylstyrene in a solvent-free reaction system achieving...

Propylene carbonate synthesis from propylene oxide and CO2 over Ga-Silicate-1 catalyst

Gallosilicate zeolite (Ga-Silicate-1) was synthesized and characterized by wet chemical analysis, Fourier transform infrared spectroscopy, X-ray diffraction, BET surface area analysis and 29Si MAS NMR. The prepared Ga-Silicate-1, calcined in the temperature range from 350°C to 550°C, was tested as a catalyst for the synthesis of propylene carbonate (PC) from CO2 and propylene oxide in a solvent-free reaction. The effects of various parameters, such as co-catalyst, reaction temperature, reaction time, and pressure of CO2, on the reaction were investigated. It has been found that increasing the calcination temperature from 500°C to 550°C decreased both the conversion and selectivity to PC from 63.7% to 20.6% and from 77.6% to 58.9%, respectively. Unlike conversion and selectivity, the surface area increased from 96.1 to 103.8 m2/g. This significant increase in surface area due to the degalliation of the zeolite, along with the decrease in conversion, clearly indicates the role of gallium in the production of PC. Under mild reaction conditions (75°C and P(CO2) = 0.55 MPa), a conversion of 70.8% and a selectivity of 81.3% were obtained. Based on the obtained results, a mechanism for the synthesis of PC over the Ga-Silicate-1 catalyst was proposed.

Novel Methodologies for Chemical Activation in Organic Synthesis under Solvent-Free Reaction Conditions

One central challenge for XXI century chemists is the development of sustainable processes that do not represent a risk either to humanity or to the environment. In this regard, the search for more efficient and clean alternatives to achieve the chemical activation of molecules involved in chemical transformations has played a prominent role in recent years. The use of microwave or UV-Vis light irradiation, and mechanochemical activation is already widespread in many laboratories. Nevertheless, an additional condition to achieve “green” processes comes from the point of view of so-called atom economy. The removal of solvents from chemical reactions generally leads to cleaner, more efficient and more economical processes. This review presents several illustrative applications of the use of sustainable protocols in the synthesis of organic compounds under solvent-free reaction conditions.