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.

Catalytic reactions play an integral role in the development of green chemistry. Herein, we report new bis-biguanide compounds containing alkyl and aryl spacers as ligands for the Suzuki–Miyaura cross-coupling reaction in water. These ligands show similar catalytic activity to metformin independently of the nature of the spacer between the two biguanide units.