A highly efficient and green synthetic protocol was developed for the synthesis of isoxazol-5(4H)-ones through a one-pot condensation of aromatic aldehydes, ethyl acetoacetate, and hydroxylamine hydrochloride in the presence of a Pumice@HClO4 catalyst under reflux conditions in water as the green solvent. Water is an inexpensive, non-flammable, environmentally benign, and non-carcinogenic solvent, making it an attractive alternative to hazardous organic solvents. The major advantages of the present method include its environmentally friendly nature, shorter reaction time, use of green solvent, and high atom economy. The Pumice@HClO4 catalyst exhibited remarkable catalytic activity for synthesis of isoxazolone derivatives. The structures of synthesized isoxazolone derivatives were characterized by 1H NMR, 13C NMR and mass spectrometry.
Fourier Transform Infrared (FT-IR) spectroscopy is a cornerstone for verifying drug loading in nanocarriers, polymeric matrices, and formulated granules. However, researchers frequently encounter the disappearance of characteristic drug peaks in the composite spectra, often leading to misinterpretations regarding loading success. This paper critically examines the physicochemical mechanisms behind this phenomenon, including signal masking by dominant substrate bands, crystalline-to-amorphous transitions, and deep encapsulation beyond the penetration depth of ATR-FT-IR. We propose a paradigm shift in spectral interpretation: the absence of discrete drug peaks does not imply loading failure; rather, subtle alterations in the substrate's spectral signature such as shifts, broadening, or intensity variations might serve as proxies for successful functionalization.
Resorcin[4]arenes are an important class of supramolecular macrocycles possessing remarkable host-guest recognition properties and broad pharmacological potential. In the present study, a novel series of resorcin[4]arene-thymine acetic acid hybrid derivatives (6a–k) was synthesized through an efficient coupling strategy employing microwave-assisted synthesis and DCC/DMAP-mediated esterification. All synthesized compounds were purified by column chromatography and comprehensively characterized using FT-IR, 1H-NMR, 13C-NMR, mass spectrometry, and elemental analysis. The synthesized derivatives were evaluated for their antibacterial, antifungal, antimalarial, antitubercular, and antioxidant activities. Several compounds exhibited promising biological profiles, particularly compounds 6b, 6f, and 6j, which demonstrated significant antimicrobial and antioxidant activities. Molecular docking studies against PDB targets 4N0K and 2H6S revealed favourable binding interactions and strong binding affinities, especially for compound 6b. The results indicate that these resorcin[4]arene-thymine hybrids may serve as promising lead molecules for the development of novel supramolecular therapeutic agents.
The increasing resistance of insect pests to conventional insecticides has heightened the urgency to discover novel chemical scaffolds that offer enhanced efficacy, selectivity, and safety profiles. Among these, isoxazoline analogs have recently emerged as a promising class of urban insecticides, demonstrating broad-spectrum activity against various agricultural and urban pests. This review aims to provide a thorough overview of advancements in the synthesis, structural diversity, and insecticidal applications of isoxazolines and isoazoles from 2016 to 2026. Recent progress in synthetic methodologies, including green chemistry approaches and innovative catalytic systems, has facilitated efficient and sustainable access to diverse isoxazoline frameworks. Structure-activity relationship studies have identified key modifications that improve insecticidal potency and selectivity while emphasizing the possibility of hybrid molecules to counteract resistance mechanisms. In addition to their high efficacy, isoxazoline- and isoxazole-based insecticides generally show favorable toxicological and environmental profiles, posing reduced risks to humans and non-target organisms compared to many traditional insecticides. The review further discusses the mechanisms of action of isoxazolines, their incorporation into integrated pest management (IPM) strategies, and their commercial applications in urban and agricultural pest control. Lastly, it addresses current challenges and future research directions, underscoring the necessity for ongoing innovation and safety assessments to ensure the sustainable use of isoxazolines and isoxazoles in modern agriculture.
A green and efficient microwave-assisted one-pot multicomponent strategy was developed for the synthesis of novel trifluoromethyl coumarin-based 4H-pyran hybrids using freshly extracted lemon juice as a natural biocatalyst. The reaction of 7-hydroxy-4-(trifluoromethyl)coumarin, malononitrile, and various aromatic/heteroaromatic aldehydes in an ethanol:water (1:1) medium under microwave irradiation afforded a series of 2-amino-8-oxo-4-aryl-6-(trifluoromethyl)-4,8-dihydropyrano[3,2-g]chromene-3-carbonitrile derivatives (4a-p) in excellent yields (86-94%) within 4-8 min. Optimization studies identified lemon juice (5 mL) under 300 W microwave irradiation as the most effective and environmentally benign catalytic system. Kinetic studies revealed pseudo-first-order behaviour, confirming the high efficiency of the lemon juice-microwave protocol. All synthesized compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, 19F-NMR, mass spectrometry, and elemental analysis. Biological screening demonstrated promising antibacterial and antifungal activities, with compounds (4l), (4m), and (4i) exhibiting the highest potency and MIC values comparable to standard drugs against selected microbial strains. Structure-activity relationship studies revealed that electron-withdrawing substituents on the aryl ring significantly enhanced antimicrobial activity. Overall, this sustainable methodology offers rapid access to biologically relevant fluorinated heterocycles and identifies promising lead molecules for the development of new antimicrobial agents.
