Sustainable access to π-conjugated molecular building blocks via phosphine-free, ppm palladium level Suzuki-Miyaura reaction in water

The use of water solutions of surfactants as the reaction medium to carry out cross-coupling reactions on water-insoluble materials is a topic of great interest in sustainable chemistry. Reactions are efficient, fast, compatible with mild or no heating, and require lower catalyst loading with respect to homogeneous phase ones performed in organic solvents. The use of supported, cheap, and widely available catalysts within the context of chemistry in water offers additional advantages: ease of removal, recovery, and recycling of the catalyst as well as a further reduction of costs and environmental impact. We here show that in the presence of a suitable surfactant, palladium-on-carbon – one of the simplest and cheapest supported palladium catalysts – is an exceedingly efficient catalyst to attain ligand-free Suzuki-Miyaura coupling of aryls and heteroaryls in water under standard laboratory atmosphere at Pd loading as low as 400 ppm.