Sulfated polyborate catalyzed expeditious and efficient three-component synthesis of 3-methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones

Na2S2O3 Catalyzed Three-Component Synthesis and Anti-Bacterial Activity of 3-Methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones

An efficient and green method for synthesizing 3-methyl-4-(hetero) arylmethylene isoxazole-5(4H)-ones was developed using a recyclable and environmental-friendly catalyst, Na2S2O3, and 16 target compounds were successfully synthesized under the obtained optimal reaction condition. Using rifampicin as a positive control, the antibacterial activity of all synthesized compounds was tested by micro dilution method, among them, 3-methyl-4-[(2,4-dimethoxyphenyl) methylene]-isoxazole-5-one (4 m) presented wonderful antimicrobial activity, which may contribute to the development of anti-tuberculosis drugs.

A green protocol for the one-pot synthesis of 3,4-disubstituted isoxazole-5(4H)-ones using modified β-cyclodextrin as a catalyst

This manuscript reports an impressive and facile strategy for synthesizing isoxazole derivatives using immobilized Cu (I) in metformin-functionalized β-cyclodextrin as a catalyst. The architecture of this catalyst was characterized by different analytical techniques such as Fourier transform infrared spectroscopy, Thermogravimetric analysis, X-ray diffraction, Field emission scanning electron microscopy, and Energy-dispersive X-ray spectroscopy. The catalyst showed remarkable reusability even after 7 consecutive runs.

Synthetic enzyme-catalyzed multicomponent reaction for Isoxazol-5(4H)-one Syntheses, their properties and biological application; why should one study mechanisms?

In this work, we describe the application of a synthetic enzyme (synzyme) as the catalyst to promote the multicomponent synthesis of isoxazol-5(4H)-one derivatives. The catalytic system could be used up to 15 times without any notable loss of its activity. Some derivatives showed fluorescence and their photophysical data were evaluated. The mechanism of the reaction was, for the first time, investigated and, among the three reaction pathway possibilities, only one was operating under the developed conditions. ESI-MS(/MS) allowed for both the simultaneous monitoring of the multicomponent reaction (MCR) and the proposition of a kinetic model to explain the transformation. The kinetic model pointed firmly to only one reaction pathway and helped to discard the other two possibilities. The antimicrobial abilities of all synthesized derivatives against Gram-positive and Gram-negative strains were also evaluated. The abilities of functional chromophores (fluorescent compounds) as live cell-imaging probes were verified and one of the multicomponent adducts could stain early endosomes selectively in bioimaging experiments.

Cu/TCH-pr@SBA-15 nano-composite: a new organometallic catalyst for facile three-component synthesis of 4-arylidene-isoxazolidinones

A copper complex supported on SBA-15 nanoparticles (Cu/TCH-pr@SBA-15) was synthesized by the post-synthesis modification of nano-mesoporous silica with 3-chloropropyltriethoxysilane (CPTES) and thiocarbohydrazide (TCH) and subsequent metal-ligand coordination with Cu(ii). These nanocomposites were thoroughly characterized by FT-IR spectroscopy, TEM, FE-SEM, EDX, atomic absorption spectroscopy and N2 adsorption-desorption (BET) studies. Then, a solvent-free method was developed for the three-component synthesis of 4-arylidene-isoxazolidinones via condensation of hydroxylamine hydrochloride, ethyl acetoacetate and various aromatic aldehydes using Cu/TCH-pr@SBA-15 as a highly efficient nanocatalyst. This new economic and eco-friendly methodology has remarkable advantages such as excellent yields, a shorter reaction time, an easy purification procedure, simplicity, green conditions, solvent-free conditions, and recoverability of the nanocatalyst.

Ultrasonically Assisted Efficient and Green Protocol for the Synthesis of 4H-isoxazol-5-ones using Itaconic Acid as a Homogeneous and Reusable Organocatalyst

Background:

Multicomponent reactions involve the simultaneous reaction of three or more components which deliver the product that incorporates the elements of all starting materials. A combination of multicomponent reaction and green solvents like water and the use of nonconventional energy sources like microwave or ultrasonication are important features of ideal green synthesis. Therefore, the design of a new multicomponent reaction and improvement of an already known multicomponent reaction with a green procedure has attracted the attention of the scientific community. Isoxazole derivatives are well known for their biological activities such as antifungal, analgesic, antitumor, antioxidant, antimicrobial, COX-2 inhibitory, anti-inflammatory, antiviral, and antimycobacterial.

Objective:

To develop a green methodology for the synthesis of 4H-isoxazol-5-ones derivatives.

Results:

Itaconic acid was used as a green catalyst for the synthesis of 4H-isoxazol-5-ones derivatives under conventional as well as ultrasound irradiation technique. Ultrasound irradiation condition requires less time for the completion of the reaction and also the yields were better.

Methods:

We have reported Itaconic acid as a green homogenous organocatalyst under ultrasound irradiation for the synthesis of 4H-isoxazol-5-ones derivatives.

Conclusion:

In conclusion, we have developed a green methodology for the synthesis of 4Hisoxazol- 5-ones derivatives. Itaconic acid is used as an organocatalyst which is biodegradable and nonhazardous. Water is used as a green solvent. Ultrasonication is used as a non-conventional green energy source. Ambient reaction conditions are used to carry out transformation for multicomponent reaction. Metal-free, mineral acid-free synthesis are key features of the present protocol.

Green Synthesis of 3-Substituted-4-arylmethylideneisoxazol-5(4H)-one Derivatives Catalyzed by Salicylic Acid

Background:

4-Arylmethylideneisoxazol-5(4H)-ones are a class of organic compounds with a variety of applications in the agriculture, filter dyes, photonic devices, and pharmaceutical industries. They are also used as synthetic precursors for the synthesis of other organic compounds. As a result, efforts are being made to search new and available catalyst and green methods toward their synthesis.

Objective:

The aim of this work is to investigate the catalytic activity of salicylic acid as an inexpensive, easy to handle, and safe catalyst to synthesis of some derivatives of isoxazole-5(4H)-ones in water medium.

Methods:

To aqueous solution of equal amounts of aryl/heteroaryl aldehydes, β-ketoesters, and hydroxylamine hydrochloride; salicylic acid (15 mol%) was added and the reaction mixture was stirred at room temperature for a specified periods. The precipitated product was filtered and washed with water to obtain 3-substituted-4-arylmethylideneisoxazol-5(4H)-ones. The reaction conditions were also optimized and extended to synthesis other isoxazol-5(4H)-ones.

Results:

The salicylic acid is found to possess acceptable catalytic activity for the promotion of three-component cyclocondensation of aryl/heteroaryl aldehydes, β-ketoesters, and hydroxylamine hydrochloride. The three-component reaction led to construction of 3-substituted-4-arylmethylideneisoxazol- 5(4H)-ones in good to high isolated reaction yields.

Conclusion:

The efficient and environmental friendliness procedure for the synthesis of isoxazol- 5(4H)-ones is introduced. The reaction also carried out smoothly in water as a cost-effective, simple, green, and non-toxic solvent at room temperature without using heating, microwave, and ultrasound sources.