A green and efficient synthesis of isoxazol-5(4H)-one derivatives in water and a DFT study

Magnetic poly(1,8-diaminonaphthalene)-nickel nanocatalyst for the synthesis of antioxidant and antibacterial isoxazole-5(4H)-ones derivatives

A magnetic poly (1,8-diaminonaphthalene)-nickel (PDAN-Ni@Fe₃O₄) composite as a multifunctional nanocatalyst was prepared in several steps including (I) synthesis of poly (1,8-diaminonaphthalene) (PDAN), (II) modification of PDAN with NiSO₄ (PDAN-Ni) and (III) preparation of magnetic nanocatalyst by iron (I and II) salts in the existence of PDAN-Ni complex (PDAN-Ni@Fe₃O₄). Fourier-transform infrared spectroscopy (FTIR), elemental analysis (CHNSO), vibrating-sample magnetometer (VSM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), field emission scanning electron microscope (FESEM), ultraviolet-visible (UV-vis), and thermogravimetric analysis (TGA) were applied to characterize the prepared nanocatalyst. The PDAN-Ni@Fe₃O₄ was applied as an environmentally friendly nanocatalyst for the isoxazole-5(4H)-ones synthesis via a one-pot reaction between aryl/heteroaryl aldehyde, hydroxylamine hydrochloride, and β-ketoester. The nanocomposite was also used for the synthesis of some new alkylene bridging bis 4-benzylidene-3-methyl isoxazole-5(4H)-ones. The catalyst's reusability, and the antioxidant and antibacterial activities of both catalyst and products, were studied. Results showed that the nanocatalyst and isoxazole-5(4H)-ones have antioxidant activity of 75% and 92%, respectively. In addition, the antibacterial test showed that the nanocatalyst and isoxazole-5(4H)-ones have highly active versus Staphylococcus aureus and Escherichia coli bacteria. The reusability and stability of the nanocatalyst, a medium to higher product yield and conversion, a faster reaction time, and the use of green solvents were a few benefits of this study.

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.