Search

A one-pot, three-component reaction between isatoic anhydride, 1,3-diketones, and amines/arylhydrazines catalyzed by a combination of molecular I2 and Et3N in open-air affords a series of quinazolin-4(3H)-one derivatives in good yield. The protocol offers an operationally simple, facile, and cost-effective pathway utilizing easily accessible reagents under mild reaction conditions with significant substrate scope. The results of steady state and time-resolved absorption and emission spectroscopy indicate the potential of quinazolin-4(3H)-one derivatives as a fluorescence probe. They exhibit unique photophysical responses in different solvent environments. In addition, they can also act as FRET acceptors during interaction with protein lysozyme. Preliminary biological studies indicate that quinazolin-4(3H)-ones are cell permeable and can be used as a fluorescent probe for bio-imaging of human cervical cancer (HeLa) cells. [ABSTRACT FROM AUTHOR]

A one‐pot, three‐component, and atom economic synthesis of biologically and pharmaceutically important fully substituted and functionalized pyrazole derivatives has been accomplished under metal‐catalyst‐free benign conditions. The strategy involves early condensation of readily available cyclic β‐diketones (dimidone, 4‐hydroxycoumarin and 2‐hydroxy‐1,4‐naphthoquinone) and arylglyoxals to generate a chalcone type intermediate which upon acid catalyzed condensation with ambident nucleophile arylhydrazones produces various aryl and cyclic β‐diketone substituted pyrazole derivatives. The synthesis embraces high functional group tolerance, broad substrate scope, excellent yield of the products, short reaction time and operationally simple and mild reaction conditions. The synthesis provides an easy opportunity of incorporating biologically important N‐diarylsulfide/selenide functionality, various enolisable cyclic β‐diketones and other bioactive heterocycles concurrently to pyrazole, which may help in designing and development of pyrazole derivatives of pharmacological significance. [ABSTRACT FROM AUTHOR]

A proline-based, chiral bi-functional organocatalyst containing both pyrrolidine and oxadiazolone heterocycle, has been successfully applied for stereoselective aldol reactions. The replacement of polar -COOH group of proline with bioisostere oxadiazolone ring provides excellent solubility of this catalyst in various organic solvents compared to low soluble proline. As a result, the organocatalyst effectively catalyzed the asymmetric condensation reaction between differently substituted aromatic aldehydes and various symmetrical and unsymmetrical ketones to produce the corresponding aldol products with excellent stereoselectivities (dr: 97:3, ee >99.9%) at room temperature in open-air. [ABSTRACT FROM AUTHOR]