Durable Heterogeneous Pd-PNP Pincer Complex for CarbonCarbon Bond Formation in Continuous-Flow Systems

A durable PNP pincer catalyst, designated "Pd-SCORPI", is developed and prepared by immobilizing a bis(diphenylphosphinoethyl)amine-Pd complex onto Merrifield resin. The heterogeneous catalyst demonstrates notable stability in continuous-flow carboncarbon coupling reactions. For the Mizoroki-Heck benchmark (4-iodoanisole and n-butyl acrylate in DMF, 120 °C, 0.05 mL min^{- 1}), Pd-SCORPI delivers a turnover number (TON) of 1115 and a turnover frequency (TOF) of 3.32 h^{- 1} while sustaining over 92% conversion for 14 days. Substrate scope analysis highlights the versatility of the catalyst, as aryl halides bearing electron-donating groups (EDGs) and electron-withdrawing groups (EWGs) couple efficiently with diverse alkenes,including challenging substrates such as acrylic acid and acrylamide derivatives. In the Suzuki-Miyaura flow protocol (4'-iodoacetophenone and phenylboronic acid in 1 : 3 H₂O/1,4-dioxane, ambient temperature, 0.05 mL min^{- 1}), Pd-SCORPI achieves a 91% isolated yield, a TON of 1242, and stable operation for 150 h. This investigation highlights the potential of Pd-SCORPI in advancing green chemistry by minimizing waste, enhancing catalyst recyclability, and promoting efficient and sustainable chemical processes, thus paving the way for scalable industrial applications.