ENHANCING REACTION EFFICIENCY IN THE GREEN PREPARATION OF 2-(2-OXOINDOLIN-3- YLIDENE)MALONONITRILES WITH ULTRASOUNDASSISTED KNOEVENAGEL CONDENSATION

Abstract

The development of 2-(2-oxoindolin-3-ylidene)malononitrile analogs has been quantitatively reported using an exceedingly feasible green methodology. This protocol involves the Knoevenagel condensation of various isatins and indeno[1,2-b]quinoxalin-11-nones with malononitrile in a solvent of EtOH under ultrasonic irradiation. This method significantly enhances the reaction efficiency, offering enormous yields ranging from 80% to 96% for the target products within a remarkably short reaction time of 10 to 15 minutes at ambient temperature. The synthesized 2-(2-oxoindolin-3-ylidene)malononitrile analogs were meticulously validated using NMR and FTIR spectroscopic analysis, confirming their structures. The methodology employed not only achieves exceptional yields but also features several green chemistry advantages, including simple workup procedures, the absence of column chromatography, the use of eco-friendly solvent, high tolerance for functional groups, and rapid reaction times at ambient temperature. This ultrasound-assisted approach underscores the importance of sustainable practices in chemical synthesis by minimizing energy consumption and reducing the use of hazardous reagents. The findings highlight the potential of this green protocol to be widely applicable in the development of various 2-(2-oxoindolin3-ylidene)malononitrile analog promoting both efficiency and environmental sustainability in organic chemistry.