Oxime Palladacycle Supported on Magnetic Meoporous Silica: An Efficient Catalyst for Copper-Free Acyl Sonogashira Reaction

The catalytic activity of the supported bis(oxime palladacycle) catalyst was evaluated in the acyl Sonogashira reaction. The reaction conditions, such as solvent, base, and palladium content, were screened to achieve the best catalytic performance. Tetrahydrofuran (THF) solvent, triethylamine (Et3N) base, and the reaction temperature of 110 degrees C were found to be ideal for achieving high yields of the desired products. Furthermore, a catalyst loading of only 0.22 mol% palladium was sufficient to achieve good conversion. Broad ranges of aryl acetylenes and benzoyl chlorides were successfully coupled to give the desired acetylenic ketones. The reaction appeared to proceed efficiently using a small amount of catalyst. The magnetic property of the catalyst allowed for easy separation using an external magnet. The catalyst was stable and reused for multiple reaction runs without a significant deactivation. After seven cycles, the catalyst maintained over 90 % of its initial catalytic activity. A bis(oxime palladacycle) anchored on Fe3O4@SBA was evaluated in the acyl Sonogashira reaction. The reaction conditions were optimized by choosing a model reaction. Broad ranges of aryl acetylenes and benzoyl chlorides were coupled to give ynones. The magnetic property of the catalyst allowed for easy separation using a magnet. The catalyst stability was shown by Pd-leaching, recyclability, and hot-filtration experiments. image