Ru-Pd Thermoresponsive Nanocatalyst Based on a Poly(ionic liquid) for Highly Efficient and Selectively Catalyzed Suzuki Coupling and Asymmetric Transfer Hydrogenation in the Aqueous Phase.

Abstract

The development of intelligent polymeric materials to precisely control the catalytic sites of heterogeneous catalysts and enable highly efficient catalysis of a cascade reaction is of great significance. Here, the utilization of a polymer ionic liquid (PIL) containing two different anions facilitates the preparation of Ru-Pd catalysts with controllable phase transition temperatures and hydrophilic and hydrophobic surfaces. The combined multifunctionality, synergistic effects, micellar effects, aggregation effects, and temperature responsiveness of the nanocatalyst render it suitable for promoting selectively catalyzed Suzuki coupling and asymmetric transfer hydrogenation in water. Above the lower critical solution temperature (LCST) of the catalyst, it catalyzes only the coupling reaction with a high turnover number (TON) of up to 999.0. Below the LCST, the catalyst catalyzes only the asymmetric transfer hydrogenation with good catalytic activity and enantioselectivity. It is important that the catalyst can be simply and effectively recovered and recycled at least 10 times without significant loss of catalytic activity and enantioselectivity. This study also highlights the superiority of multifunctional heterogeneous catalysts based on PILs, which not only overcome limitations associated with low activity of heterogeneous catalysts but also realize selective reactions according to a temperature change, thereby improving the reactivity and enantioselectivity in multiple organic transformations.