Qing Liu

Bio: Qing Liu is an academic researcher. The author has contributed to research in topics: One-pot synthesis & Ethyl acetoacetate. The author has an hindex of 1, co-authored 1 publications receiving 36 citations.

One-Pot Three-Component Synthesis of 3-Methyl-4-Arylmethylene- Isoxazol-5(4H)- Ones Catalyzed by Sodium Sulfide

Abstract: 3-Methyl-4-arylmethylene-isoxazol-5(4H)-ones were synthesized by the convenient three-component reaction of ethyl acetoacetate, hydroxylamine hydrochloride, and aromatic aldehydes catalyzed by sodium sulfide in the presence of ethanol at room temperature. The advantages of this procedure were mild reaction conditions, high yields, short reaction time, and operational simplicity.

Boric acid-catalyzed multi-component reaction for efficient synthesis of 4H-isoxazol-5-ones in aqueous medium

Abstract: The one-pot three-component reaction of aryl aldehydes with hydroxylamine hydrochloride and ethyl 3-oxobutanoate/ethyl 4-chloro-3-oxobutanoate/ethyl 3-oxo-3-phenylpropanoate in the presence of boric acid, H3BO3, in water leads to 4H-isoxazol-5(4H)-ones in high yields. The merits of this method are efficiency, simplicity, clean, green, easy work-up, high yields, and shorter reaction times.

Efficient tandem synthesis of a variety of pyran-annulated heterocycles, 3,4-disubstituted isoxazol-5(4H)-ones, and α,β-unsaturated nitriles catalyzed by potassium hydrogen phthalate in water

Abstract: A variety of 4H-chromenes, benzochromenes, 4,5-dihydropyrano[3,2-c]chromenes, 4H-pyran-3-carboxylates, and 3,4-disubstituted isoxazol-5(4H)-ones have been synthesized in high yields by using potassium hydrogen phthalate (KHP) as an inexpensive, commercially available catalyst. It was found that the three-component tandem reaction enabled synthesis of pyran-annulated heterocycles in water at 50 °C. 3,4-Disubstituted isoxazol-5(4H)-ones were synthesized by use of 10 mol% KHP in water at room temperature. Also, treatment of methylene-containing compounds (malononitrile or ethyl cyanoacetate) with aromatic aldehydes in the presence of 5 mol% KHP resulted in α,β-unsaturated nitriles. The procedure is an easily performed, straightforward method for synthesis of a variety of pyran-annulated compounds, isoxazol-5(4H)-one-containing heterocycles, and Knoevenagel adducts. The reaction is safe, uses mild conditions, and is environmentally benign. Other notable advantages are reuse of the catalyst, no use of hazardous organic solvents, and ease of work-up.

Fruit juice of Citrus limon as a biodegradable and reusable catalyst for facile, eco-friendly and green synthesis of 3,4-disubstituted isoxazol-5(4H)-ones and dihydropyrano[2,3-c]-pyrazole derivatives

Abstract: Fruit juice of Citrus limon (lemon juice) has been utilized as a natural and renewable catalyst for the green and environmentally friendly preparation of 3,4-disubstituted isoxazol-5(4H)-one derivatives and 6-amino-1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile derivatives in hydroalcoholic media at 90 °C. A one-pot three-component reaction of β-oxoesters with hydroxylamine hydrochloride and various aromatic aldehydes afforded 3,4-disubstituted isoxazole-5(4H)-one derivatives in excellent yields. The rate constant (K = 6.12 × 10−2 min−1 at 25 °C) for the formation of isoxazole derivative (1g) was also calculated. Similarly, a four-component reaction of ethyl acetoacetate, hydrazine hydrate, aryl aldehydes, and malononitrile gives pyrano[2,3-c]-pyrazole derivatives in very good yields. After completion of the reaction, the products were isolated by simple filtration. A simple work-up process, high product yields, short reaction times, and the use of an inexpensive and biodegradable catalyst are the advanced rewards of the present protocol.