Exceptionally high turnover frequencies recorded for a new chitosan-based palladium(II) catalyst

To be industrially feasible, and applicable in synthesis of fine chemicals, a catalyst has to possess high turnover number (TON) and turnover frequency (TOF). In this study, a new cross-linked chitosan derivative was synthesized by using 2,2′-pyridil as a cross-linking agent. 2,2′-Pyridil cross-linked chitosan was used to as a support material for palladium catalyst. Chitosan-pyridil-based Pd(II) catalyst was tested in the microwave-assisted synthesis of biaryls via Suzuki coupling reactions. The catalyst yielded remarkable TONs of up to 20,000 and TOFs of up to 240,964 by using very low catalyst loading (5 × 10-3% mol) in a short reaction time (5 min). The catalyst also showed a better recyclability.