Metformin as a versatile ligand for recyclable palladium-catalyzed cross-coupling reactions in neat water†
We present the high catalytic activity of an in situ generated palladium(II)/metformin complex in neat water for the Suzuki–Miyaura and Sonogashira cross-coupling reactions. These reactions were performed in pure water without any co-solvent or mass transfer agent. The palladium(II)/metformin complex gave excellent to good yields for the Suzuki–Miyaura coupling reaction and catalyzed with a certain specificity to the aryl iodide coupling in the Sonogashira reaction. The methodology showcases a recyclability up to four catalytic runs for the Suzuki–Miyaura cross-coupling reaction, performed with only 0.5 mol% palladium loading.